Latest 50Watt LM3876 Power Amplifier Circuit diagram and explanation

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My cause of construction of this project was to develop a compact design for a stereo amplifier can be integrated by a wrong (but the sound quality conscious!) Living student at a university or a college dormitory.
audio amplifier 50W circuit

audio amplifier 50W circuit
The amplifier feeds a pair of speakers with two LM3876 amplifier integrated circuits (50 watts per channel), or a pair of headphones Meier Crossfeed through a filter and a dual OPA2134 Opamp. There are four selectable line inputs, and output buffers with line level for the registry. The design with readily available components of good quality, and is divided into four BPC, a power amplifier for each channel, for the nutrition board, and for the pre-amp / headphone driver.
Above the diagram of part of the preamp board .
The output selector is sent to pins J1 and J3. Looking at the left channel, C1 and R2 form a low pass filter with a-3dB point of 40 kHz, which rejects any RF interference picked up on the interconnections. R2 also includes the impedance of the device, in this case, 47k ohms. R1 ensures Opamp U1 is presented with an impedance equal to its two inputs, contribute to improving the performance of the distortions described in the datasheet OPA2134.
The value of R1 (9K1) is universally accessible, close to the value of the parallel combination of R3 and R4 (22k and 15k, respectively). R3 and R4 set the gain at that time, just below 2.5 in this case. This gives ample space for a wide range of signal sources, which could be as much as 3VRMS. In this case, the peak output voltage of 10.6V would be fine with the project to supply ± 15V.

This initial gain brings the signal to a level that the output of the volume can lead the power amp circuits directly without any additional benefit, and allows the helmet of the driver circuit to operate with a low gain, gives lower noise level. C7 forms 100kHz a lowpass filter with R3, to fall on the gain of unity at very high frequency, and to help promote stability in the Opamp. It is not strictly necessary for the proposed OPA2134 allows the unit, but down substitute cheaper but more likely oscillation device, such as the NE5532, if budgets are tight. C19 couple the AC output of this phase for volume control, and with a 50k potentiometer, the-3dB point of the response of the headphone amps at 1.4Hz (power amp has more HIGH PASS FILTER). The capacitor is very important because all the other stages are DC coupled and DC C19 prevents any of the source components, amplification and presentation of headphones or speakers.

Resistance R9 binds the production of inputs to a recording device like a VCR or mini-disc. This helps to prevent the source being loaded in the diet of both the gain stage input and the recording device and protects the source, the output should be shorted to earth for a reason whatsoever. The output from J5 and J6 are introduced into the volume control pot, which should be good quality. Finally, C3 to C6 and provide decoupling of the power supply rails, C5 and C6 high frequency decoupling, C3 and C4 lower decoupling.

IC TDA7294 120 Watt Audio Power Amplifier Circuit Amplifer with IC number TDA7293 for process sound system. This amplifer was have the input for a



IC TDA7294 120 Watt Audio Power Amplifier Circuit

Amplifer with IC number TDA7293 for process sound system. This amplifer was have the input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source. With the addition of a low pass filter at the input, it makes a great amp for a small subwoofer.

Parts

R : 660 Ohm 1/4 W Resistor = 2 pcs.
R : 22K 1/4 W Resistor = 5 pcs.
R : 10K 1/4 W Resistor = 1 pcs.
R : 30K 1/4 W Resistor = 1 pcs.
C : 2200uF 35V Electrolytic Capacitor = 2 pcs.
C : 0.22uF Capacitor = 2 pcs.
C : 22uF Capacitor = 4 pcs.
C : 0.45uF Capacitor = 2 pcs.
U1,2 : TDA7294 100W DMOS AUDIO AMPLIFIER WITH MUTE/ST-BY

T1 : 50V Center Tapped 5 Amp Transformer
S1 : SPST 3 Amp Switch
S2 : DPDT Switch
F1 : 2 Amp Fuse
SPKR1 : 8 Ohm 120W Speaker
MISC : Case, Knobs, Line Cord, Binding Posts Or Phono Plugs (For Input And Output), Heatsinks For Q1 And Q2

Remote and Touch Volume Controls by MC3340P circuit Remote and Touch Volume Controls by MC3340P

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circuit Remote and Touch Volume Controls by MC3340P

12V DC Motor Speed Controller by 4011 this is circuit 12V DC Motor Speed Controller by 4011.

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this is circuit 12V DC Motor Speed Controller by 4011.

Infrared Intruder Alarm circuit Infrared Intruder Alarm

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circuit Infrared Intruder Alarm

Opto-Thermo Control Relay Switch with IC 741 Circuit Opto-Thermo Control Relay Switch with IC 741



Circuit Opto-Thermo Control Relay Switch with IC 741

Breadboard Development System Known as Pro-I/O

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Breadboard Development System Known as Pro-I/O

Overview

The Pro-I/O breadboard development system was designed based on an Atmel Atmega16 microcontroller in order to emulate various input and output devices.

Explanation

The Pro-I/O connects to the target breadboard using a 40-pin cable that is equipped with all the input and output signals for the target interface. It also has several power and ground pins that can be used to power smaller designs. Instead of an RS232 serial connection, it includes a USB interface since power can be obtained from the PC easily through USB. The use of highly integrated ATmega16 microcontroller makes it possible to do several things than just debouncing a few pushbuttons and displaying a hexadecimal character of two.

Other components that comprise the device include 2 voltmeters, frequency counter, frequency generator, small serial terminal, LEDs, 2x16 characters LCD display, pushbuttons, and switches. The PC is used as the user interface because it is much easier and cost effective due to the number of functions that the device can perform.

The software for ATmega16 is written in C while considering the GNU-based WinAVR toolset that includes a compiler, programming software, and large set of C library functions with AVRISP.

www.circuit-projects.com

4066 Quad Switch Based Noise Box

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4066 Quad Switch Based Noise Box

Overview

The gating properties of the 4066 Quad Switch is the basis of this Noise Box which aims to produce a truly horrible sound/noise that is amplified by an LM324 Quad op-amp.

Explanation

The use of 4066 for gating signals is for controlling the switches which are very sensitive to the electro-magnetic fields of the body and other objects known as Theremin. When something is near the antennas attached to the pins during operation, the switches get confused and start triggering. The positive and negative signal is split and routed to separate switches on the IC. A switch based patch feeds on the gated output of the 4066 IC and distributed to the various configurations of the op-amps.

A stereo signal or 2 separate signals can be used for this particular device which has a triangle, integral, difference, and summing/fixing shaper configuration. The output of the op-amps will be mixed by routing to another switch bank and the output set of RCA jacks allows sound to flow.

Most of the space is occupied by the 2 sets of 9V batteries which provide the power to the device. Instead of perfboard, it uses point-to-point connection.

Dead Bug Style Known as MMR-40 Overview and Explanation

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Dead Bug Style Known as MMR-40

Overview

The project aims to produce SSB (voice) and CW (Morse code) operating modes on a low-power 40-meter rig with CW or PEP output of up to 6 watts.

Explanation

This rig project can be built using 3 construction methods which include the printed circuit version, pseudo circuit board method, and dead bug method. There are advantages and disadvantages however for each method but in this project, more details were provided on the dead bug method to build the MMR-40. There are several stages that can be tested during the construction of the MMR-40. The PTO oscillator is the first stage followed by the audio and control circuit, the receiver section, and the transmitter sections.

A coil wound makes up the PTO which is supported by two brass nuts soldered to the copper foil of the board. The side to side play in the tuning screw is eliminated by a third nut. In building the PTO oscillator circuit, the J310 JFET and 7805 regulator are mounted with their legs in the air. Some parts are lying down or at an angle. The oscillator feedback turns come out to the correct pads through L2 coil.

Frequency Counter and Timer Development Overview and explanation

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Frequency Counter and Timer Development

Overview

The project employs a sliding window for calculation of multiple frequency updates per second on this frequency counter and timer.

Explanation

During the operation, a 1Hz resolution up to 100MHz is being provided in the counter mode while the maximum resolution is 0.0000001Hz up to 1Hz in the timer mode. For each additional decade, the resolution is reduced by one digit. It uses an ATmega8 AVR microcontroller along with high-speed CMOS 4-bit counter 74HC93 and high-speed CMOS latch 74HC573. It also has 3 to 8 multiplexer 74LS138 and 16MHz crystal oscillator. The LEDs are driven by BC177 transistor but any PNP type can be used.

The 7 additional input bits are provided by the switch interface at the cost of only one Mega8 pin. For mode control switches, the inputs used consist of input select, method select, display select, and reserved for future extensions. A few modifications must be made in case the AVR should be programmable in circuit. The 47K resistors were used to isolate all third parties on wires used for programming. A low pass is created by the resistors in combination with Mega8 which is software compensated using increased settling time.

I2C Interfaced with NXT DIy Overview and Explanation

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I2C Interfaced with NXT

Overview

The goal of the project is to provide 8 digital I/O ports with the NXT by using a simple I2C chip with either binary input or output on each one of these 8 ports.

Explanation

The I2C serial digital protocol is supported by the sensor ports on the NXT and the inputs can either be ON or OFF. Touch sensor-like switches can be used for the input ports while the output ports can drive LEDs and turn motors ON or OFF through relays or other devices. This project drives LEDs using two ports and four ports unused. Connected to push switches are the two other ports used as inputs.

The PCF8574 I2C chip provides 8 bidirectional binary ports which can be connected to the sensor port’s 4.3V supply directly since it requires a supply voltage of 2.5V-6V. It can drive LEDs directly as it supplies 25mA to each port. Higher loads can be driven by connecting pairs of outputs in parallel.

On the I2C, a clock signal is carried by one wire and the data signals by the other one since it is a 2-wire serial bus. It has one master communicating with slave devices.

Battery charger By LM2575

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1 A current sources for battery charger applications based on the LM2575–ADJ switching step–down converter and the MC33341 regulator control circuit, pdf file

LM2575 Switching Regulator 1.2-12V for Solar

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Here is circuit power supply switching regulator, use IC LM2575 (good and easy IC switching regulator) for cotrol Voltage output 1.2V – 12V From Input Voltage 12V-20V. Detail see in circuit.

LM2575 Switching Regulator 1.2-12V for Solar

This circuit is suitable for a variety of uses. If you have a solar powered 12 Volt lead-acid battery power source, the circuit can be used to efficiently power lower voltage devices. It can be used to provide power to devices that normally use a set of small batteries for power. Common voltages such as 1.5V, 3V, 4.5V, 6V, 7.5V, and 9V can be produced by this circuit….

Please Read More in site source: http://www.solorb.com/elect/solarcirc/buckreg1/index.html
Thank you.

Autonomous Parallel Parking RC Car full circuit and explanation

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RC Car

Side View of RC Car

Arjun Nagappan (asn28)

Arjun Prakash (asp36)

Introduction

We created an RC Car that can identify a parking space and parallel park by itself. The RC Car drives down a street searching for a parking space to its right using a distance sensor. When the car has identified a space, the car checks to see whether that space is large enough to park in. If it determines that there is sufficient space, the car will begin parallel parking into that space. It uses information from sensors placed on the front, right, and rear of the car to direct the car into the parking space. Once the car has parked, it will remain in that position until it is reset.

High Level Design

Rationale | Logical Structure | Hardware/Software Tradeoffs

Rationale

After discussing various project ideas, we eventually stumbled onto the subject of cars. So we started brainstorming possible projects related driving. When brainstorming, we saw something in the ECE lounge that reminded us of a garage. This led us to parking. Parallel parking is something that many drivers struggle with, yet there are very few tools available to help with parallel parking. Though a few auto manufacturers have developed systems that can parallel park cars autonomously, these solutions are very expensive. We thought this would be both a fun and interesting problem to tackle using an RC Car as a proxy for a real car.

Logical Structure

Our project is broken down into two major components: the control system and the move car algorithm. The move car algorithm directs the car and the control system implements the directions of the move car algorithm.

Design Structure

Figure 1: Logical Structure of High Level Design

Control System

The control system contains all the hardware and its associated software. It allows the parking and parking detection algorithms to interface with the car. The software in this module is broken up into three major sections: the Left-Right/Front-Back (LR/FB) state machines, master state machine, and distance calculations. The LR/FB state machines determines which direction to move the car based on flags set by the detect parking space and park car algorithms. Once the LR/FB state machines decides which direction to move the car, the master state machine implements this movement by sending the correct input and enable signals to the H-Bridge. The distance calculations implemented independently every millisecond.

Move Car

Move car contains the detect parking space and parallel parking algorithms. All functions in move car interface with the control module by setting movement flags. The parking space detection and parking algorithms use information from the distance sensors to set these movement flags and guide the car.

Move car works by initializing the movement flags of the car. It sets the car on a default trajectory and then calls detect parking space. Once a parking space has been detected, the parking algorithm is called. After the car has successfully parked, it idles until it is reset.

Hardware/Software Tradeoffs:

Distance Sensors

  1. When selecting infrared distance sensors there was always a tradeoff between the sensors ability to measure close range and long range. We tried to minimize this problem by using sensors designed for varying ranges.
  2. Using accurate sensors cost significant time. Every measurement from our distance sensors is approximately 40ms delayed. This affected our ability to start and stop the motors of the car at the correct times.
  3. We used integer calculations rather than floating point to calculate distances. We decided the increased accuracy would not significantly improve our ability to park the car because we cannot control the movement of the car with that degree of accuracy.
  4. Each sensor draws a maximum of 50mA. To accommodate for this, we needed to use a 5v regulator that could source up to 1A.

Batteries

  1. We decided to power our car using batteries rather than using a steady power source. This gave us increased mobility but was very inconsistent in the current it supplied to the motors. As the batteries wore out, they supplied less and less current to the motors. This made calibrating the velocity of the car very difficult.
  2. In order to best utilize the mobile power resources we have, we power the motors using four AA batteries, which are stored in the battery compartment of the RC car. These batteries supply the Supply Voltage to the H-bridge, which in turn powers the motor. We use a 9V battery to power the PCB.

Software

  1. 1. Our code requires the motor control software, parking algorithm software, and distance sensor software to run in parallel. However, this is not possible in the Atmega644. We got around this issue by making every important task a state machine. By breaking up each function into small pieces, we can execute one piece of function one, then one piece of function two, followed by one piece of function3, and then another piece of function one, etc. This enables us to emulate a multi-tasking architecture.

Hardware

RC Car | H-Bridge | Distance Sensors

Hardware consists of three main components:

  • RC Car
  • H-Bridge
  • Distance Sensors

All hardware used the following color convention:

Color Connected To
Red Vss
Green Ground
Purple Input
Yellow Output
Orange Enable

Table 1: Wire Color Convention

RC Car

The first step of our hardware design involved fully understanding the mechanics our RC car. We took apart the car and rebuilt it multiple times to fully understand how it was built, what every part in the car is used for, and how those parts contribute to the control of the car.

After understanding the mechanics of the car, we decided the easiest way to control our car would be to directly control the inputs to the DC brush motors controlling the front and rear wheels, bypassing all of the car’s internal circuitry. To do this, we scoped the control signals of the car. We found that the control signals were very simple. There is one motor for the reverse and forward movement of the rear wheels and one motor to turn the front wheels left and right. These motors are controlled by a simple 5V DC input. A +5V turns the rear wheels forward and the front wheel to the left. A -5V input turns the rear wheels backwards and turns the front wheels to the right. To more easily control the motors we soldered wires to their plus and minus terminals. This allows us to easily apply a +/-5V without opening up the car again.

H-Bridge

We use an ST Micro L298HN H-Bridge to control the motors of the RC Car. It allows us to switch between +/-5V across the motor. It also allows us to source the power from the batteries while using the processor to control the transistors in the H-Bridge. The control algorithm turns the appropriate transistors on/off, applying the proper voltage across the brush motor. The H-Bridge is connected using the following configuration:

H-Bridge Schematic

Figure 2: H-Bridge Schematic

The first H-Bridge (to the left) is used to control the front motor of the car. This motor turns the front wheels either left or right. The second H-Bridge (the the right) is used to control the rear motor, which is used for the forward and reverse functionality of the car. The inputs and enables of the H-Bridge are connected to port B.

Front Motor (Left/Right) Rear Motor (Forward/Reverse)
Pin Connected To Pin Connected To
In 1 Port B7 In 3 Port B3
In 2 Port B6 In 4 Port B2
En A Port B5 En B Port B1
Out 1 + Motor Terminal Out 3 + Motor Terminal
Out 2 - Motor Terminal Out 4 - Motor Terminal

Table 2: H-Bridge Pin Configuration

In addition configuring the H-Bridge to control the motors, we also had to protect the H-Bridge from inductive spikes caused by turning the DC brush motors on and off. We used diodes on the output to protect from these spikes. The H-Bridge was wired as follows:

H-Bridge Current Portection

Figure 3: Inductive Current Protection on H-Bridge Outputs

Distance Sensors

We used three Sharp infrared distance sensors to determine the distance between our car and nearby objects. We placed a sensor on the front, the right side, and the rear of the car. For the front and rear, we used 4-30cm sensors. For the right side, we used we used a 10-80cm sensor. We decided to use a sensor with a larger range for the side so that we could more easily detect a parking space. However, this made aligning the parking the car more difficult, so we rely more heavily on the front and rear sensors to park the car. To slightly improve the short distance range of our sensors, we placed the sensors as far back on the car as possible.

The challenge with using these sensors is that their voltage output is nonlinear (inverse function) and each sensor varies slightly. Therefore, we scoped the output of each sensor at various distance values, linearized the plot, curve fit the line, and implemented an analog to digital conversion so that we had reliable distance values.

Measurements and Linearization

Distance (cm) Front Sensor Output (V) Rear Sensor Output (V)
4 2.78 2.6
5 2.36 2.22
6 2.06 1.92
8 1.6 1.52
10 1.32 1.26
12 1.12 1.08
15 .92 .88
18 .776 .76
21 .664 .656
24 .567 .576
27 .536 .52
30 .476 .48

Table 3: Front and Rear Sensor Measurements

Front Sensor Data Front Sensor Data

Figure 4: Front Sensor Plots of Distance vs. Voltage and Distance-1 vs. Voltage

Rear Sensor Data Rear Sensor Data

Figure 5: Rear Sensor Plots of Distance vs. Voltage and Distance-1 vs. Voltage

After taking the inverse of the distance versus voltage plots, we determined it would be best to fit the curve using two linear lines rather than one. The equations of the lines are:

Front Sensor Rear Sensor
voltage=9.759*[1/distance]+0.381, >1.5V voltage=8.963*[1/distance]+0.395, >1.25V
voltage=12.738*[1/distance]+0.057, <1.5v voltage=11.806*[1/distance]+0.09, <1.25v

Table 4: Front and Rear Distance Sensor Equations

The analog to digital conversion uses a different equation depending on the value of the measure voltage. If the measured voltage is above a certain threshold, the ADC will use the equation in the top row. If it is below a certain threshold, the ADC will use the equation in the bottom row. The threshold for the front sensor is 1.5v and 1.25v for the rear sensor.

Distance (cm) Side Sensor Output (V)
10 2.28
15 1.64
20 1.28
25 1.08
30 .808
35 .728
45 .672
50 .612
55 .556
60 .516
65 .488
70 .452
75 .432
80 .42

Table 5: Side Sensor Measurements

Side Sensor Data Side Sensor Data

Figure 6: Rear Sensor Plots of Distance vs. Voltage and Distance-1 vs. Voltage

When looking at the data for the 10-80cm side sensor plot, we determined that one linear line would be sufficient to accurately capture the output voltage vs. distance characteristics of the sensor. The equation of this line is:

voltage=21.592*[distance]^(-1)+0.173

Analog to Digital Conversion

For the analog to digital conversion we used the built in ADC function of the MCU. Because we had three distance sensors, we had to rotate which sensor was connected to the ADC. This was simply done by changing the value of ADMUX. One of the three sensors is sampled every millisecond.

We take the value from the ADCH register and perform the appropriate calculation to convert this value to a distance. We decided to use only the ADCH register because the value represented by the bottom two bits of the ADC is on the same order of magnitude as noise. Therefore, these two bits are not important to our calculation. To do this, the ADC is left adjusted. By using the value in the ADCH register, we are using the upper eight bits of the ten ADC bits. We use the internal reference voltage of 2.56V for comparison, so our calculation is:

ADC Calculations ADC Calculations ADC Calculations ADC Calculations ADC Calculations

Software

Control Module | Algorithm Module

The software for this project has been partitioned into 2 files based on functionality. There are 2 files, ControlModule.c and AlgorithmModule.c.

The state machines in ControlModule control the motors, and are:

  • fbStateMachine
  • lrStateMachine
  • masterStateMachine

The state machines in the AlgorithmModule use the sensor data and various algorithms to determine what should be the next movement the car must make. They assert flags which tell the ControlModule state machines to actually move the motors. The state machines in AlgorithmModule are:

  • moveCar
  • detectParking
  • parkCar

Below we have explained the various state machines we have used in our project.

Control Module

fbStateMachine()

Function:

The fbStateMachine controls the motor for Forward-Backward operations. It is controlled by the isForward and isReverse flags. These flags serve as indicators as to whether the car should be traveling forward or reverse. In order to control the velocity of the forward-backward motion we anded the enable bit with a a PWM signal.

Working:

In State 0, the motor is at rest. The corresponding FB control bits are 00. When the algorithm requires the car to go forward or reverse, the corresponding flags (isForward and isReverse) are set, and the FB state machine switches states to 1 or 3 respectively.

In State 1, the motor rotates to drive the car forward. The state machine remains in this state while isForward is equal to 1. Once isForward is de-asserted, the state machine moves to a buffer state to stop the car from moving forward due to inertia.

After isForward is set to 0, leaving state 1 and stopping the motor isn’t enough. The wheels might continue to rotate due to inertia, and so a buffer state, State 2, is required. It makes the motor go in Reverse for 1 cycle (50ms) of the FB State Machine, before going back to the rest state, State 0.

If isReverse is asserted, the state machine jumps to State 3. The state machine remains in this state while isReverse is equal to 1. Once isReverse is de-asserted, the state machine moves to a buffer state to stop the car from moving in reverse due to inertia.

After State 3, a buffer state, State 4, is needed to stop the wheels from continuing to rotate in reverse due to inertia. This is a 1 cycle Forward motion, similar in function to State 2’s reverse functionality. Once done, the FB State Machine goes back to its rest state, State 0.

Timing:

The fbStateMachine is called upon every 50ms. This is enough time to evaluate the flags set in the AlgorithmModule, but at the same time fast enough to make the motor motion very accurate.

lrStateMachine()

The lrStateMachine() works the same way are the fbStatemachine. A forward corresponds to a left turn and a right corresponds to a reverse. The diagram for both are:

BF/LR State Machine

Figure 7: FB/LR Motor State Machine

masterStateMachine()

Function:

This uses the FB and LR control bits to call the required functions in order to send the appropriate input signals to the H-Bridge and make the motors rotate in the appropriate direction.

Working:

In this function, the 2 FB and LR control bits are combined to create 4 master control bits by left shifting the FW bits by 2 and adding it to the LR bits.

Therefore,
fbBits = fb.controlBits; // (FB FB)
lrBits = lr.controlBits; // (LR LR)
masterBits = (fbBits<<2)>

As a result, each of the 7 car movements (stop, forward, forward-left, forward-right, reverse, reverse-left, reverse-right) have a unique masterBits combination associated with them. The master control bits are then used in the function to decide which motor control function is to be called.

Timing

This state machine is invoked in each iteration of the infinite while loop in main. In other words, it can be considered to be executing continuously and not at intervals. This is essential because parking requires a great deal of accuracy when controlling the motors. Therefore, we want to update the motors as often as possible, which would require us to call masterStateMachine as often as possible.

Algorithm Module

moveCar()

Function:

This is the master state machine of the algorithm module. It decides which mode the car is in, i.e., whether the car is moving forward to detect a parking spot, aligning itself once a parking spot has been detected, or actually going through the motion of parking.

Diagram:

Move Car State Machine

Figure 8: Move Car Motor State Machine

Working:

This is a 5 state linear state machine, as can be seen in the diagram above.

It starts off in State 0. In this state, the car is at rest. It gives enough time for all transients in the car to stabilize. Once everything is stable, it moves to State 1.

In State 1, car moves forward till it detects a parking spot. While in this state, the car invokes the detectParking state machine each time the moveCar state machine is called in the Control Module. Details of how the detectParking state machine works are explained in the next section.

Once a parking lot has been detected, the state machine moves into State 2. It remains in State 2 until the car has parked itself. The parkCar state machine is invoked for each cycle that the moveCar state machine is in State 2. Once the car has been parked by parkCar state machine, the isParked flag is asserted, and moveCar moves onto state 3.

When we reach State 3, the car parked itself. The car will eternally remain in this state hereafter, since the car has parked itself and is at rest.

In addition to serving as a state machine as described above, moveCar also makes available 2 values – rsDist and rrsDist – to its sub-state machines, detectParking and parkCar. rsDist stores the values of the side distance in the previous clock tick of the moveCar state machine, while rrsDist stores the value 2 clock cycles earlier.

Timing:

The moveCar state machine is invoked every 100ms. The moveCar state machine also serves as a clock for the detectParking and parkCar state machines. When in State 1, each clock tick of the moveCar state machine serves as a clock tick for the detectParking machine. When in State 3, each clock tick of the moveCar state machine serves as a clock tick for the parkCar machine.

detectParking

Function:

The function of detectParking state machine is, as its name suggests, to detect a parking space to park in. It accomplishes this by continuously polling the distance values from the side distance sensor.

Diagram:

Detect Parking Space State Machine

Figure 9: Detect Parking Space State Machine

Working:

detectParking is a 6 state state machine, as can be seen in the diagram above.

State 0 serves as a start-up. This is essential because the first few cycles of the detectParking take place while the side distance sensor is still calibrating itself. Once the wait state is done, the state machine enters state 1.

State 1, essentially, searches for a sudden increase in the side distance value. A sudden increase corresponds to the beginning of a parking space. It does this by checking the (sDistance – rsDist) value. If there is a sudden depression, sDistance will increase and so it’s difference from its own previous value (rsDist) will be a large number. When this does occur, the state machine goes onto State 2.

In State 2 it attempts to confirm that it indeed is detecting a valid depression, by calculating (sDistance – rrsDist). Since State 2 is invoked 1 clock tick after the depression was last detected in State 1, rrsDist will store the value of the side distance before the depression began, i.e., from 2 clock cycles earlier. If (side distance – rrsDist) is still a large number, we can confirm that a depression has been detected, and we move to State 3.

In State 3, we keep track of how long the depression is. This is done by incrementing the detect.controlBits for each state machine clock tick that we are still in the depression. When there is a sudden decrease in the value of the side distance, we move to state 4, since it signals a probable end of the parking lot.

State 4 confirms that the possible end of the parking space, as detected in State 3, is indeed the end of the space. This is done in a manner similar to the confirmation done in State 2 using the rrsDist variable.

Once a parking space has been detected by the above states, the state machine moves into State 5 wherein it checks the control Bits (which kept track of how long the parking space was by incrementing for each cock tick while in the depression) to make sure the parking space is large enough. If large enough, then the isParkingLot flag is asserted which would direct moveCar to stop and start the parking sequence.

Timing

Each tick of the detectParking state machine corresponds to a tick of the moveCar function. When moveCar is in State 1, it calls detectParking on each of its ticks. Therefore, detectParking is called every 100ms until a parking space has been located.

parkCar()

Function:

The function of the parkCar state machine is to park the car once a parking spot has been identified. The algorithm to park the car continuously interacts with its surroundings through the forward, side and rear sensors.

Diagram:

Park Car State Machine

Figure 10: Park Car State Machine

Parking Motion

Figure 11: Parking Motion of Car, colors correspond to state of the Park Car State Machine

Working:

The parkCar function tries to simulate how a human would parallel park. It is, essentially, just the following 4 motions:

  1. Reverse Right until you are inside the parking lot.
  2. Go Forward and redo 1. if the car is not aligned.
  3. Reverse Left until the car is fairly straight and close to the back wall.
  4. Forward Right until the car is straight and close to the front wall.

The above routine is accomplished using a 7 state machine.

State 0 makes the car move forward by a certain amount. The idea is to give the car enough space to move and rotate into the parking space.

State 1 simply turns the front wheels to the right. We turn the wheel before reversing the car so as to not lose turning radius by turning as the car reverses. Once the wheel is turned, the state machine moves onto state 2.

State 2 commands the car to go reverse right for a specified amount of time until the car has passed the edge of the parking space. Once past the edge of the space, it moves to state 3.

In State 3, the car continues in reverse right until it is either a certain distance from inside of the parking space, or the rear distance is close to the edge. These conditions, as can be seen from the figure above, are checks to verify that the car is deep enough inside the parking lot to be able execute the reverse left maneuver. Once the conditions are met, the car stops and the state machine moves to state 4.

NOTE: If at any point in states 1, 2 or 3 the car’s AI decides it is not in a position to go through with the parking, it will go back to State 0, and redo the whole procedure.

In State 4, the car moves reverse left. It does this until the rear of the car is close to the side wall of the parking space, which can be judged by the rear distance sensor value. Once close enough to the rear value, it stops and moves to state 5.

State 5 commands the car to go forward right. This attempts to straighten out the car completely and to align it nicely inside the spot. It goes forward right until it is close to the side wall of the parking space, as judged by the forward distance sensor. Once aligned, the car is parked and it moves to state 6.

State 6 is a 1 cycle stop before progressing back to state 0. Also, here the isParked variable is set so that the moveCar state machine can move out of parking mode to rest mode.

Timing:

Each tick of the parkCar state machine corresponds to a tick of the moveCar function. When moveCar is in State 3, it calls parkCar on each of its ticks. Therefore, parkCar is called very 100ms while the car is being parked.

Misalignment Detection

Our parking algorithm is equipped with a Misalignment Detector. Its role is to judge whether the car can park itself in the given space, and if it judges that parking is impossible, to correct the car’s position to make it possible.

Our algorithm has a provision to keep track of the values of distance from the side sensor (sDIstance) from the earlier clock (rDist) and earlier 2 clock ticks (rrDist) of the state machine. Having these 2 values is extremely important to the successful working of the misalignment detector.

The detector works by checking how much sDIstance has changed over the last 2 clock cycles. If the change in sDistance is large, it means the car is not ideally positioned and it will set the park car state machine to the forward state. It will also define how long the car should remain in this state. This can be seen in the figure below:

Misalignment Detection

Figure 12: Example of Misalignment Detection

What is beautiful about this whole setup is that this exactly how a human would park the car! If the driver realizes that he is not aligned well enough, he will go forward and try again.

Putting it All Together

If you have taken a look at the high level design described earlier in the code, and read the description of the state machines in the earlier section, you have all the information you need to understand how the software of the car works.

Essentially, the AlgorithmModule state machines are what set the flags to control the movement of the car. These flags are interpreted by the ControlModule state machines, and translate it into actual motor control.

Results of Design

Speed of Execution | Accuracy | Safety and Interference | Usability

Speed of Execution

Speed wasn’t a big issue for us. All components of the software were done as state machines.

The Motor Control state machines update at ticks every 50ms. This was ample time for the state machines to compute the necessary controlBits and assert the required inputs to the H-bridge. As a result, we were able to obtain highly accurate and sensitive responses from the motors to the control code.

The Algorithm Control state machines update at ticks every 100ms. This was enough time for the state machines to compute the necessary parameters, and to assert the necessary flags for the Control Module to interpret them and translate it into motor motion.

The response of the car to its surroundings is also very fast. The sensors have a response time of 20ms, which is quick enough for them to be processed in real time.

Accuracy

Distance Sensors

The sensors were very accurate within their specified range. Even with integer calculations, we were able to calculate distances with a +/- 1cm accuracy. Because we could not control the movement of the car with this degree of accuracy, the accuracy of our distance sensors are sufficient.

Parking Space Detection

The sequence to detect a parking space works very accurately. In the many trials that we performed, it always detected the parking space and stopped on detection.

Parking Algorithm

The parking algorithm we have written works very well when the car is close to a set distance from the side of the parking lot. It, however, becomes less accurate when the car is placed at larger distances from the parking space.

The parking algorithm we have written works very well when the car is close to a set distance from the side of the parking lot. It, however, becomes less accurate when the car is placed at larger distances from the parking space.

Safety and Interference

There were not many safety concerns with our project. In order to minimize disturbance to other project groups, and avoid the car colliding into students, we made a separate test area in the hallway. We used this test area for all testing purposes.

Also, since the car is completely autonomous, there was no human contact required (except for turning on the car). Therefore, there wasn’t an issue of interference with the systems in the car.

Usability

In our opinion, this project has tremendous potential. With some more work on the parking algorithm, we feel that we can develop a system for the RC car to park irrespective of its orientation and distance from the parking lot. With enough research, this can be developed for real cars!

It can also be used as a learning tool for people who want to learn driving. By observing the motion of this car, students can learn how to parallel park better.

Lastly, this project could serve as a useful reference point for future projects dealing with R/C cars. The Control Module we have implemented to control the R/C car can be used universally for any 2-wheel drive R/C car.

Conclusion

Standards, IP, and Legal | Ethical Considerations

Overall, we feel the project met most of our expectations, as we were able to build an autonomous car which could detect a parking space, and park in it. When we started out, we intended the car to be able to locate a parking spot, and park irrespective of its distance from the parking space and its orientation. We were, however, unable to make it robust enough to accommodate parking from different orientations and distances. However, we feel the basic algorithm would remain the same, and this algorithm can be built upon to accommodate these features.

This was also a tremendous learning experience for us, especially with the hardware. We learn a tremendous amount about motor control systems, efficient circuit design, and hardware debugging. We also learned a lot about software. Through this project, we got valuable experience in developing efficient software using memory and run-time optimizations, something that cannot be gained through routine assignments.

If we had an opportunity to start this project over, there are a few things we would do differently.

  1. Use a regulator to ensure a steady current is being supplied to the batteries despite the fluctuation in voltage across the batteries, particularly as they lose power
  2. Consider implementing an optical sensor to track the velocity of the car
  3. Build a feedback PWM loop to control the velocity of the car
  4. Consider adding a fourth sensor on the side to calculate the orientation of the car
  5. Consider building the car ourselves

Standards, Intellectual Property, and Legal Concerns

There were no standards or regulations that concerned our project because we decided not to control the car using radio signals. There are also no concerns with intellectual property because we purchased the RC car and are only using it for personal use. All the software and other hardware was designed by us.

Ethical Considerations

We adhered to the IEEE Code of Ethics throughout this project. We were very careful to consider the effects of our decisions on us, those around us, and the outcome of our project. We took significant time to plan our project before implementing it. We wanted to ensure our car was designed in the best way possible, in terms of performance, reliability, and safety. We worked cooperatively with other people, seeking and providing feedback and constructive criticism from the professor, TA's, and other groups to build the best possible design.

We also set up a safe testing environment. In an area with high traffic, people could have easily stepped on the car and been hurt. We tested our car in a highly controlled environment to ensure everyone’s safety. We did not make any decisions that would cause harm to others or the environment.

In no circumstances did we give or accept bribes. All of our parts were either bought or sampled in the appropriate manner. We have been honest regarding the results and limitations of our design. We have worked hard to create the best design possible in the given time frame, and it is safe to operate. All people involved with this project were treated fairly.

Appendix

Commented Code | High Level Schematic | Parts List and Cost | Tasks | References

Appendix A: Commented Code

This link contains the source code for our project: Source Code

This link contain supplementary functions we wrote during the development of our project: Supplementary Code

Appendix B: High Level Schematic

High Level Schematic

Appendix C: Parts List and Cost

Part Number Cost
RC Car 1 $20
10cm-80cm Sharp IR Sensor (GP2Y0A21YK) 1 Free (Sampled From Sharp)
4cm-30cm Sharp IR Sensor (GP2D120XJ00F) 2 Free (Sampled From Sharp)
ST Micro H-Bridge (L298HN) 1 Free (Sampled from ST Microelectronics)
ATMEGA 644 1 Free (Sampled from Empire Technologies)
Custom PC Board 1 $4
Small Solder Board 1 $2
9V Battery 1 $2
AA Battery 4 $2
Headers 65 $3.25
Regulator (LM340T5) 1 Free (In Lab)
Screws and Spacers
Free (In Lab)



Total
$33.25

Appendix D: Tasks

Both of us contributed to all parts of the project, however we spent more time working on certain things.

  • Design of Hardware: Nagappan
  • Design of Control Algorithm: Both
  • Design of Parking Algorithm: Prakash
  • Testing of Hardware: Both
  • Testing of Software: Both
  • Compiling Report and Web Site: Both

latest free Fast Acting Electronic Circuit Breakers

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Fast Acting Electronic Circuit Breakers

The circuit breakers on this page make use of the Zetex - ZXCT1009 "High Side Current Monitor' integrated circuit. The circuits have variable trip current settings and are designed for low current applications.

Zetex - ZXCT1009 "High Side Current Monitor'

The current sensing IC is placed in the supply side of the circuit ahead of the isolation device. This allows the common line of the circuit to remain free of voltage dropping resistances.

For information on the operation of the ZXCT1009 current monitor itself, please refer to the manufacturers data sheet at - ZETEX - ZXCT1009 Data Sheet (PDF)


Two circuit breaker designs are shown; The first has its power isolation device on the Low or common side of the circuit while the second has it isolation device on the High or supply side of the circuit. Both designs use MOSFET devices to isolate the suppiy from the load.

The overload detection and trip system is completely electronic and therefore has a very fast response time (1/120th of a second or less for a full wave DC supply). This allows the load to be disconnected almost instantaneously when an over current condition is detected.



- Low Side Isolation Circuit Breaker -

This circuit has its isolation device, Q1, on the Low or common side of the circuit. The disadvantage of this method is that the breaker cannot easily be used in typical circuit configurations that share a low side or negative common.

The method is simple to implement however and a wide range of output devices are available. The transistor used to test this circuit was a IRL520 MOSFET


Low Side Circuit Breaker

Circuit Controls and Indicators

  • S1 resets the circuit after and overload trip has occurred.

  • ROUT - ADJ adjusts the tripping current level.

  • LED - D2 will turn OFF when an overload has occurred and the circuit has tripped.





- High Side Isolation Circuit Breaker -

This circuit has its isolation device, IC 3, on the High or Supply side of the circuit. This allows the circuit breaker to be more easily used in typical circuit configurations that share a low side or negative common.

IC 3 is a PROFET® BTS409L1 - 'Smart High Side power Switch' from INFINEON.


High Side Circuit Breaker

Circuit Controls and Indicators

  • S1 resets the circuit after and overload trip has occurred.

  • ROUT - ADJ adjusts the tripping current level.

  • LED - D2 will turn OFF when an overload has occurred and the circuit has tripped.

LED - D3 is optional and is connected to the internal diagnostics system of the BTS409L1 and will turn ON to indicate various fault conditions. These are listed in the BTS409L1 data sheet.



Very - Basic Operation Of Both Circuit Breakers

  1. As the current through RSENSE increases the voltage across resistors ROUT - MAX and ROUT - ADJ increases proportionally.

  2. When the voltage at the MINUS input of IC 2A rises above the voltage at the PLUS input its OUTPUT will go LOW.

  3. When the OUTPUT of IC 2A goes LOW it causes the Flip-Flop formed IC 2B to change states, producing a LOW condition at it's OUTPUT.

  4. Depending on the circuit used, a LOW at the output of IC 2B causes the Gate of Q1 or the Input Terminal of IC 3 to go LOW. This will cause Q1 or IC 3 to turn OFF and open the circuit.



Circuit Breaker Page Notes

  • The maximum Input to Output voltage of the ZXCT1009 is 20 Volts. There are ways to increase this voltage but these are not shown on this page.

  • With the component values shown the calculated adjustable trip current range is between 0.23 and 3 amps.

  • A heat sink may be required for transistor Q1 or IC 3 at higher current levels.

  • Capacitor C3 provides a short delay time so that the circuit automatically resets itself when power is applied.

  • Capacitor C4 prevents the circuit's protection from being disabled if S1 is held closed. This means that when S1 is held closed the circuit will reset and then will quickly trip again if an overload is present. If C4 is not used the circuit breaker cannot trip as long as S1 is held closed. This may be desirable in certain situations and might be considered as an option.

  • Both Q1 and IC 3 have internal diodes to protect them from being reversed biased. This could happen if the power transformer's fuse failed while the breaker was connected to a circuit with a large filter capacitor. In this case reverse current would be shunted around the isolation devices and into the circuit breaker's power supply until the circuit had been discharged.

  • Diode D1 and capacitor C1 provide a short term sub-power supply for the control circuitry in case there is a drop in the voltage of the main supplies voltage during a dead short at the output of the breaker.

  • For more information on voltage comparators please refer to this page; Voltage Comparator Information And Circuits.

  • There are other devices from Zetex and other manufactures that could also be used in this type of circuit.

  • The ZXCT1009 used has a SOT-23 surface mount style case that is quite small. To aid in using this device a "PROTO-BOARD ADAPTER FOR SOT-23-5" listed as DigiKey part number 33205CA-ND. is recommended. (The distance between the pins is 0.100in or 2.54mm.)

Circuit and explanation of Ornamental LED

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The circuit is a simple Astable multivibrator using two NPN transistors T1 and T2.The circuit works on the principle of charging and discharging of capacitors C1 and C2. Current from the positive of battery flows through first set of LEDs D1-D5 to the collector of T1 through resistor R1. Resistor R1 limits current through the LEDs to protect them. The current through R1 and LEDs charge capacitor C1. It then discharges through the base of T2 and resistor R4. This gives base current to T2 and it conducts. As a result second set of LEDs D6-D10 lights.As the Capacitor C1 discharges completely, T2 turns off. LEDs D6-D10 also turns off. The same thing happens in the other side also. This gives alternate flashing of LEDs.Thus the flashing effect is produced through the switching of T1 and T2 by the charge from capacitors.Flashing rate can be changed by changing the value of R3,R4 or C1,C2. If 500K preset is used in the place of R3/R4, flashing rate can be varied.

Ornamental LED Circuit

D.Mohankumar

http://electroschematics.com/6099/ornamental-led/

Controlling the power of a flash with a tv remote

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Controlling the power of a flash with a tv remote



Controlling the power of a flash with a tv remote

For those who do fancy photography, setting up the lighting ends up being one of the larger tasks of each session. There are flashes out there that can be controlled via a remote control to help ease the process, but they can cost a considerable amount more. [Dsvilko] shares with us a fairly simple circuit that allows you to use a tv remote to control your flash. He’s using a picaxe 08m and he states that before this project, he had never messed with microcontrollers. We say great job on your first microcontroller project. You can catch a video of it in action after the break.

[via Makezine]

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Via Hack a Day, Published: 2010.09.23

DashPC System for Volkswagen expanation

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DashPC System for Volkswagen

Overview

Built into the dashboard of a car is an integrated computer console known as DashPC which was interfaced from the center console to a mounted 6.4” VGA LCD display.

Explanation

Aside from the LCD touchscreen, the platform of the DashPC is interfaced through multiple input methods like a handheld wireless keyboard with pointing device and wireless remote control. One of the most advanced carputers is the DashPC telematics where its technology virtually works in any vehicle. Some of the features included in thes DashPC prototype vehicles include an OBDII onboard engine interface, DVDs, and GPS.

The startup and shutdown of the computer is transparent to the user and is being handled by the BS2-IC. The computer begins to boot one second after the car is started. The in-dash VGA LCD turns ON when the Linux operating system is ready to be used. The DashPC simultaneously offers powerful expansion capability while being designed to be simple to use in a vehicle environment.

The boot device used is a 512MB Memorex CF card as the computer contains VIA 9000 Motherboard & CPU, 256MB PC133 RAM, 40GB IBM 2.5” HD for general storage, and Linksys Wireless Ethernet card.

Smart & Fast Battery Charger for NiCd/NiMH circuit and explanation

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Smart & Fast Battery Charger for NiCd/NiMH

Overview

The project utilizes MAX712/MAX713 fast charge controllers in order to build a smart & fast NiCd/NiMH battery charger.

Explanation

The MAX712 is designed for NiMH batteries and the MAX713 is for NiCd batteries where the battery-fully-charged sensing method is the only difference between them. The values for some of the components included in the circuit can be chosen using the reference from Maxim. Depending on the number of cells of the battery pack intended to charge as well as the charging time, those values may vary.

The charger won’t be able to charge packs with more than six 1.2V cells if it is powered only with 12V. the MAX will get hot and the charging current won’t be what is expected from the value of the sensing resistor if something bigger than 12V would be tried. This is due to the sinking of as much current as possible from the base of the power transistor as it tries to obtained up to 250mV voltage drop on the sensing resistor.

The timer feature of MAX712/713 cannot be disabled while a high current could still be a result of the maximum possible charging time.

Simple and Low-Cost Homemade MIDI Turntable overview and explanation

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Simple and Low-Cost Homemade MIDI Turntable

Overview

An Atmega16 microcontroller is the main component in developing this MIDI turntable along with a HDNS-2000 optical mouse encoder, GCC-AVR, AVR-Libc, and free RTOS.

Explanation

The YA and YB from HDNS-2000 IC are the two available inputs that can be found inside the optical mouse. The direction of the movement and velocity of the turntable can be determined with these two inputs. The output information for MIDI and for three LEDs is provided by the microcontroller which sends by MIDI information about the movement of turntable. The activity of the microcontroller is shown by the flashing of one LED while the movement of the turntable turns the other two LEDs.

The values of MIDI come from the moving mouse which changes in Puredata. The red LED turns ON for about 2 seconds and turns OFF for 1 second. The directions of the mouse movement are represented by the yellow and green LED. Each time the MIDI messages are sent using the MIDI-USB converter, the LED is flashing at 50ms.

The input power is regulated by the 7805 IC which also provides 5V constant output. Any older turntable or rotate plate can be used.

LM555 Timer Used As A Voltage Comparator Or Schmitt Trigger

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The next section shows how the LM555 timer could be used as a voltage comparator or a wide offset Scmitt Trigger. Applications for which it is not particularly well suited but one that is in wide use with model railroaders.
Shown on the schematic is a secondary output that uses the open collector at the DISCHARGE terminal (Pin 7) of the timer. This output can sink up to 200 milliamps and would be ideal for driving relays.
The main disadvantage to using this circuit is the the large dead-band (1/3Vcc) between upper and lower threshold voltages. An optional resistor, R5, can be added to the circuit to lower and compress the detection voltage range but this only partially alleviates the problem. [...]

Read more source: http://home.cogeco.ca/~rpaisley4/LM555.html

Comparator Oscillator Circuit by LM311

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Comparator Oscillator Circuit by LM311 or LM339

Comparators can also be used as oscillators but are not well suited for this type of application.

Comparator Oscillator Circuit by LM311


Source : http://home.cogeco.ca/~rpaisley4/Comparators.html

Battery Monitoring By LM324

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It has been stated in other pages on this website that it is a very good idea to have two separate batteries, one for the drive (weapons and wheels), and one for the radio control receiver and other electronics (see Speed controllers and EMC sections). It is very useful to know the state of charge of both of these batteries so that you do not go into a bout with uncharged batteries, but do not have to continually charge them when they are already charged (which can degrade the batteries).

Battery Monitoring By LM324

This page describes two methods of determining the state of charge of the batteries.

We can see from the discharge curve of the lead acid battery, that if we compare the terminal voltage with a fixed value of about 1.75V per cell (10.5v for a 12v battery, 21v for a 24v battery), we will get an idea of when the battery is in its terminal decline point. Note however that the discharge curves depend on how much current is being drawn from the battery at the time. This is because while drawing current, there will be a small voltage drop across the internal resistance of the battery. Hence at large current drains, the battery monitor may indicate a flat battery when it is actually OK. Therefore the monitoring should only be done (or only taken notice of) when no current is being drawn from the battery.

The voltage of the lead-acid reaction when fresh is typically around 2.15v per cell. A further comparison threshold can be put at around 2.0v per cell (12v, 24v) to indicate that the battery is down to about 25% charge left. These limits are a bit arbitrary, so we should allow them some trimmability.

A circuit diagram of the battery monitor is shown below:
The comparators are powered from the battery itself, so to get a battery voltage input which isn’t at the same value as the comparator supply (comparators would not work well like that), the battery voltage is divided by the trimmer resistors. This is compared with a value generated from the precision voltage reference. Opamps are used for the comparators since no pullup resistor is then required (comparators generally have open-collector/open-drain outputs which require a pullup resistor to make wired-OR functionality easier. They are also normally much faster then opamps at comparing, but we do not require any speed, or the wired-OR function).

The oamp after the trimmer and the opamp after the precision voltage reference are connected as buffers, and are there to ensure that the trimmer and reference do not have to supply any reasonable current which would affect their output voltages.

The 2.0V comparator LED is connected to the output of the 1.75v comparator. This ensures that when the battery voltage falls to below 1.75v and that comparator’s output goes low, the 2.0v LED will extinguish, and only the 1.75v LED will be lit. The series resistors on the LED should have the value

Read More Source :

http://homepages.which.net/~paul.hills/Circuits/BatteryMonitor

latest Simple switching regulator by LM358 , 78L05 circuit and explanation

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Simple switching regulator by LM358 , 78L05
This circuit uses a standard 78L05 low power 5v regulator in a novel way – as a voltage reference to a comparator. When the output voltage is LOWER than 5v, the output of the comparator switches high, turning on the transistor. The output voltage rapidly rises and once it is HIGHER than 5v, the output of the comparator switches low, turning off the transistor. The 0.33uF mono capacitor provides some smoothing and prevents oscillation in the multi-megahertz region. Under no load this circuit oscillates at about 32KHz. The diode and 470uF electro provide isolation and extra smoothing to produce an almost pure DC output.


Source : http://www.rowan.sensation.net.au/electronics/stepdown2.html

Compares with sound level tool

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A tool that use for fine to decorate the sound of , organ , piano , have the pitch is equal. By have the accuracy is similar to with compare with the sound of the professional. But use the ability in listenning sound beat. At happen between 2 frequency sounds that confute by use origin frequency pillar circuit in 250.830 kHz frequency occurrences. For feed to reach first part of 5 IC. Which build the circuit divides by the frequency model a program.

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