PIC Based Auto Dimmer circuit schematic with explanation


The operation of the dimmer is based on phase control; during a full cycle of an AC waveform, a thyristor will only allow a part of the waveform to be delivered to the load. Take a look at the following waveforms:

PIC Based Auto Dimmer  circuit schematic with explanation PIC Based Auto Dimmer  circuit schematic with explanation

The only difference is that the waveform on the left will bright the lamp higher than the waveform on the right. That is because, on the left waveform, the triac will be conductive earlier than the triac shown in the right waveform.

The time that the triac becomes conductive is symbolized with the Greek letter α (ALPHA) , called firing angle, so controlling this angle you can control the phase voltage, and is measured in angles from the zero point of the waveform. This zero point is the point that the voltage is 0 volts, and this happens 2 times every one full period of the wave form. When the α becomes smaller, then the dimmer becomes conductive sooner and the lamp is brighter. When the α becomes bigger, then the triac delays more to become conductive and thus the lamb is dimmer.


A full wavelength period is 360 degrees (2π). Due to the fact that during a full wave length the zero cross occurs twice, α can take values from 0° to 180 degrees (0 - π). When α = 0°, the full power is delivered to the load and when α = π, no power is delivered to the load.

The zero cross detection circuit is the most critical part when designing a dimmer. This circuit will watch the input power waveform and detect when this waveform crosses the 0 point and becomes 0 volts.


Zero cross detection circuits are mainly used in cases when the dimmers needs to be controlled from a micro controller. In that case, the micro-controller needs to know the zero cross detection point of the waveform, so that it can calculate the angle offset to send the trigger pulse to the gate of the triac.

In this case i am using three second delay for auto changing the brightness and interrupt for zero crossing. The range required for my test is 10% to 90% means 22v to 198v for 220v ac.
Also note me using 4Mhz crystal with 22pF capacitors.

Video:


Download: Code n Files

Schematic:
PIC Based Auto Dimmer  circuit schematic with explanation
MCU Based Auto Dimmer
Components Required:
R1-R3, R6-------------------------10k ohm
R7-R8-----------------------------1k ohm
C1----------------------------------10nF Ceramic
Q1----------------------------------BC547
Q2----------------------------------BC557
U1----------------------------------PIC16F628A
U2----------------------------------BT136 Triac
Bridge Rectifier
4MHz Crystal
22pF Ceramic (2)

Serial Communication With PIC18F452 circuit schematic with explanation

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Serial Communication With PIC18F452

In this tutorial I will explain how to practically do a simple communication over RS232 interface. In this tutorial i ll send and receive the data using serial port, in two devices. Also you can control your home appliances using PC serial port with the help of PIC. RS232 is serial interface that means that data is transferred BIT by BIT at a time. Since data is transferred BIT by BIT so we need only a single wire two send data and an another one to receive data. One more common wire (called GND) is required between two separate circuit to enable current flow. So a total of three wire are required for communication.

RS232 can be used to communicate between a variety of devices. Like your MCU and a GSM module or a PC. In this tutorial we will demonstrate a link between a PIC18F452 MCU and a standard PC. On PC we will run a terminal program like RealTerm or Hyperterminal.

A terminal program is used to send and receive text data. So any text send by the MCU will be visible on Terminal Screen and Any keypress you make on the PC keyboard will be send over RS232 to your MCU. This configuration is the simplest setup to test and understand RS232 communication. When you have enough knowledge you can replace the Terminal with your own PC end software for sending receiving data.

In this tutorial i will only talk about the simulation in Proteus, using its own terminal. If you want to communicate it with the PC then you have to convert the TTL to RS232 logic, for this see the level converter.

Hyper Terminal in windows (if using windows 7 then download RealTerm) is located in communication folder. Create the new connection and set the properties as follow:
  • Bits per second: 57600
  • Data bits: 8
  • Parity: None
  • Stop bits: 1
  • Flow Control: None
Code of serial communication is written in form of library to work with USART. This keeps the USART code separate from the application code. The same library can be used in many other project that requires USART communication. The functions available in the library are discussed below.

void USARTInit()
This function initializes the internal USART of the PIC18F452 microcontroller. This must be called before data can be sent or received.
void USARTWriteByte(char ch)
Writes a byte of data to the USART.

void USARTWriteString(const char *str)
This function will send a string of character to the serial port.

unsigned char USARTReadByte()
Wait until a byte is received from USART/Serial Port and return the value read from the USART.

Downloads: Code Files

Schematic:
Serial Communication
Virtual Terminal of Proteus

Telephone Line Powered LED Lamp circuit schematics with explanation

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Telephone Line Powered LED Lamp

This small and bright LED lamp is telephone line powered, means it uses the power of our telephone line. There are about -40v to -50v at telephone line, LM317T is used to adjust them according to our demand.
12 white LEDs of 5mm dia is used in this lamp, are all in series to compensate the voltage. Out of four wires of telephone only red and green is of our interest. This telephone line powered LED lamp is small, efficient and bright; one can also be use this for study or desk lamp.
Telephone Line Powered LED Lamp  circuit schematics with explanation


Schematic:
Telephone Line Powered LED Lamp  circuit schematics with explanation
Telephone Line Operated LED Lamp
Components Required:
BR2----------------------Bridge Rectifire
U2------------------------LM617T or LM317L
R3-------------------------270 ohm 1/2watt
R4-------------------------6.8k ohm
12 white LEDs

PICkit 2 Clone circuit schematic with explantion

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PICkit 2 Clone

There are many PIC programmer available, commercial and DIY devices. As Microchip introduces the new microprocessors the programming software got to be updated accordingly playing catch-up with the PIC manufacturer. That is the root of the problem with third-party PIC programmers. Microchip's PICkit 2 is the low cost ICSP programmer for Flash PICs with USB interface introduced by Microchip. Only subset of PIC microcontrollers is supported, but the list is including all the recent devices from PIC16, PIC18 and PIC24 families and certainly covers all the PICs you are most likely want to use. It is fully integrated with Microchip’s MPLAB IDE and allow not only program but debug applications as well.

PICkit 2 was originally built by Microchip as open design programmer with the schematic, source code and firmware available to boost the popularity of the PIC devices. Because of that it is easy to build a clone version of the original device. Most of the clones will produce unregulated 5 volt VPP where the original Microchip PICkit 2 provides adjustable VPP output to allow 3.3 and 2.5 volt parts programming.

The schematic I have used is based on the original PICkit 2 having compatibility to programe the low voltage devices, means can also provide 3.3v VPP as well as 5v VPP, and without programmer-to-go functionality. That functionality allowing a hex file to be downloaded to the PICkit 2 to later program PIC microcontrollers without a PC with a simple pressing programmer's push button. I do not think that functionality is required for a hobbyist but allows simplify the schematic by omitting two 24C512 EEPROM chips. Recently i tested PIC16F877a and PIC18F452 successfully.
PICkit 2 Clone
Here is mine

ICSP

The pin-out for Microchip standard 6-pin connector for In-Circuit Serial Programming (ICSP) is listed in table below:
Pin Function
1 _MCLR/Vpp (programming voltage)
2 Vcc(+5V)
3 GND
4 Data
5 Clock
6 LVP (low-voltage programming mode control)


Schematic:
PICkit 2 Clone
PICkit 2 clone

Pin Out:
PICkit 2 Clone circuit schematic
USB b type connector

Components Required:
R1,R6,R11,R12,R14-------------------------10k ohm
R2,R3,R5------------------------------------330 ohm
R4,R8,R22,R23----------------------------4.7k ohm
R7--------------------------------------------1k ohm
R9--------------------------------------------100k ohm
R10------------------------------------------2.7k ohm
R13-------------------------------------------100 ohm
R15,R17,R19---------------------------------10 ohm
R16,R18,R20--------------------------------33 ohm
R21-------------------------------------------820 ohm
C1,C2-----------------------------------------22pF ceramic capacitor
C3,C5-----------------------------------------100nF ceramic capacitor
C4---------------------------------------------1uF/16v electrolyte cap
C6---------------------------------------------47uF/16v electrolyte cap
X1---------------------------------------------20MHz crystal
D1---------------------------------------------red LED
D2---------------------------------------------green LED
D3---------------------------------------------1N5817
D4---------------------------------------------4.3v zener diode
D5,D6-----------------------------------------1N4148
Q1,Q2,Q4,Q5---------------------------------BC548
Q3,Q6-Q8------------------------------------BC558
J1----------------------------------------------USB connector B type
J2----------------------------------------------3 pin jumper
J3----------------------------------------------6 pin connector
U1----------------------------------------------PIC18F2550
L1----------------------------------------------680uH
Misc-------------------------------------------Push Button

Low Cost Capacitive Touch Switch II circuit schematic with explanation

Low Cost Capacitive Touch Switch II

In my previous post of capacitive touch switch, it gives the o/p as long as you touch it. Means it was only drive the load when you touch it, and when you remove your hand/finger then it was not able to drive the load. Tough that touch switch circuit can be used in various apps but does not meet my requirements. So by changing the circuit a little bit i am able to design a touch switch that behave like a normal switch i.e touch to on and touch to off.

For this i used CD4017 decade counter. Output of 40106 drives this counter and load is connected to the pin2 of the counter, and reset is to pin4. When you touch the touch plate (wire in my case) a pulse is provided to the counter and it increments its o/p. So as the load is connected to the Q1 of counter, the o/p is high to drive the load. Similarly if you want to switch off the load and again touch the plate; counter will increment again and reset itself and make Q0 high. As your load is not connected to this pin it will go off. That is all!.
Low Cost Capacitive Touch Switch II  circuit schematic with explanation
Video:

Schematic:
Low Cost Capacitive Touch Switch II  circuit schematic with explanation

Components Required:

R1------------------------------6.8k ohm
R2------------------------------10k ohm pot
R3------------------------------100k ohm
R4------------------------------10M ohm
R5,R6--------------------------10k ohm
R7------------------------------1M ohm
R8------------------------------1k ohm
C1,C4--------------------------1nF
C2,C3--------------------------100nF
IC1-----------------------------40106
IC2-----------------------------CD4017
D1------------------------------1N4148
LED
Q1------------------------------2N5457

Mobile Phone Battery Charger circuit schematic with explanation

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This battery charger circuit is for Sony Ericsson standard batteries, Li-Polymer type, with a nominal voltage of 3.6V and a capacity of 900mAh. But you can also charge Nokia batteries as well.

Charging lithium cells is fairly straightforward. You generate a well regulated voltage and ensure the charging current is sufficiently low so as not to cause overheating problems. Also, when the correct terminal voltage as been attained, it is important to shut down the charging process at that point.
The circuit consists of three main sections:
  • A 5V DC constant voltage supply, which serves as the charging source for the mobile phone battery. Mains voltage is transformed via T1. After rectification and smoothing, via BR1/C1, about 14V DC is delivered to IC2, which is a 1A 5V regulator. The regulator output delivers the charging current to the mobile phone battery via current limiting resistor R1 and via relay contacts RLA2. Fuse FS1 provides protection in the event of excess current flowing for whatever reason.
  • A 6V constant voltage reference source, which provides the ‘setpoint’ for the switched charge controller. A means of producing a reference voltage equal to the fully charged battery open circuitvoltage is required. (4.15V in the case). This is achieved by utilisingan LM317 device (IC3), which is an adjustable 3-terminal positivevoltage regulator capable of supplying in excess of 100mA over an output voltage range of 1.25V to 37V.This voltage regulator is exceptionally easy to use and requires only two external resistors to set the output voltage. Thus, resistors R2 and R3 set the LM317 output at about 6V, and this potential is applied acrosss a pot (VR1), the wiper (moving contact) picks off 4.15V and applies it to the inverting input of IC1.
  • A voltage comparator device, with an associated 12V relay switching and latching the circuit. Op amp IC1 is an LM358N, and is configured as a voltage comparator. The non-inverting input is connected directly to the +V ternminal of the mobile phone being charged via the 10kΩ resistor R5. When a discharged battery is connected into the circuit, the non-inverting input of IC1 will be lower than the inverting input, and IC1 output will be at, or near to 0V. Transistor TR1 will be switched off and relay RLA will be de-energised. Under this condition, relay contacts RLA1 will permit energising of LED1 (charging), and relay contacts RLA2 will permit the charging current to flow from IC2 via R1 into battery B1. As the battery accumulates charge, eventually, the battery voltage will slighty exceed the setpoint voltage (4.15V) and the output of comparater IC1 immediately swings fully positive and switches TR1 on, which in turn energises relay RLA. Relay contacts RLA1 now latches the relay, thus ensuring that no over-charging can take place and contacts RLA2 energises LED2, the ‘charge complete’ indicator. The battery is then disconnected from the charger, which is reset by removing the mains supply ready for the next charging cycle.

Schematic:
Mobile Phone Battery Charger circuit schematic with explanation
Mobile Phone Battery Charger
Components Required:
R1-----------------------------10 ohm
R2,R7-------------------------270 ohm
R3,R8-------------------------1k ohm
R4-----------------------------2k ohm
R5------------------------------10k ohm
R6-----------------------------47k ohm
R9-----------------------------470 ohm
VR1----------------------------2k pot
C1------------------------------100uF/25v Electrolyte
C2------------------------------150nF
C3------------------------------470nF
C4------------------------------100nF
C5------------------------------1uF
IC1-----------------------------LM358N
IC2-----------------------------LM7805
IC3-----------------------------LM317
D1------------------------------1N4148 or 1N4007
RLA----------------------------12v two pole relay
TR1-----------------------------BC300
T1-------------------------------12v sec transformer
BR1-----------------------------Bridge Rectifier
FS1------------------------------250mA fuse
LED1----------------------------red LED
LED2----------------------------green LED

Video Amplifier with Sync Stripper and DC Restore (EL8102)


Introduction

The circuit in Figure 1 transmits 200MHz (-3dB bandwidth) video signals while stripping off the sync pulse and performing DC restoration. It is configured for a typical video cable driver application driving a double-terminated 75Ω load, where the EL8102 (IC3) is configured for a gain of +2 to ensure unity gain throughout.



Sync Stripping

In component video systems it is frequently necessary to remove the sync pulse from an RGB signal. Sync is often combined with one or more of the red, green, and blue video signals in video distribution amplifiers, routers and switchers to decrease the number of input and output channels required in a switching network. In many applications, however, as the video signals exit the switching network the sync pulse must be removed.





The EL8102 video op amp is specially designed to perform sync stripping. Its open emitter NPN output forms an emitter-follower with the load resistor, and passes the active video signal while virtually eliminating the negative sync pulse (see Figure 2). Residual sync of the EL8102, defined as the remainder of the original -300mV sync pulse, referenced to ground, is only 8mV at the cable output. A particular advantage of sync stripping with the EL8102 is the resultant larger (by 0.7V) output voltage swing, compared to simply using a wideband video op amp with an external emitter-follower.



Because the EL8102 contains no active pull-down, output linearity degrades as the signal approaches ground. To deal with this a 6.8kΩ pull-up resistor (R8) and a 75Ω pull down resistor (R10) on the output ensure a fixed positive voltage offset, in this case +50mV. This offset was arbitrarily chosen as a good compromise between linearity near the DC level and minimum residual sync. Increasing R8 decreases residual sync, at the expense of linearity. Conversely, decreasing R8 decreases linearity error, but increases residual sync.Other applications benefitting from sync removal are HDTV systems and video digitizing circuits. Consider a typical 1VP-P RGB video signal with a -300mV sync pulse and +700mV video data. By stripping off the unwanted sync pulse and digitizing only the active video, designers can use the full dynamic range of the A/D converter for the +700mV video data. This results in a 30% increase in resolution using the same A/D converter.



DC Restore

Another common video function is DC restoration, used when AC coupled signals have lost their DC reference and must have it periodically reset in order to retain brightness information.

This circuit accomplishes DC restoration using a CA5260 dual op amp (IC1a, IC1b) coupled with a sample-and-hold circuit based on the 74HC4053 switch (IC2). VIN, consisting of the input video signal and a DC offset (VDC), is routed to the non-inverting input of the EL8102 (IC3). The EL8102 is configured in a gain of +2 (to compensate for the attenuation resulting from double terminating the cable), which would result in an output of 2 x VIN = (2 x Video + 2 x VDC), if not for the DC restore circuit.



VIN also travels through half of the dual CA5260 amplifier to the sample-and-hold circuit, where the 0.1µF capacitor (C1) is the hold capacitor. The sample-and-hold control is triggered by a back-porch pulse from a sync separator or by a horizontal video blanking signal. The DC output signal (VDC) from the sample-and-hold circuit is then amplified at a gain of +2 by the second op amp (IC1b); the gain is required because VDC is input to the EL8102s inverting input which provides only a gain of -1, but as discussed earlier, the output contains a term of 2 x VDC. Thus 2 x VDC is summed into the EL8102 inverting input, is subtracted from the output signal, and yields a DC restored video signal.



Because the output impedance of IC1b is high, and would affect the gain at the non-inverting input of the EL8102, a 47µF capacitor (C2) is used to provide an AC ground and to maintain good high-frequency gain accuracy.

A potentiometer (R3) is used prior to IC1b to null out any offset voltage contributed by the DC restore circuitry.





Conclusion


The circuit's resultant output is a 200MHz, DC restored video signal in which the sync pulse has been stripped to a residual level of no more than 8mV.

Telephone Line Powered LED Lamp circuit schematics with explanation

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Telephone Line Powered LED Lamp

This small and bright LED lamp is telephone line powered, means it uses the power of our telephone line. There are about -40v to -50v at telephone line, LM317T is used to adjust them according to our demand.
12 white LEDs of 5mm dia is used in this lamp, are all in series to compensate the voltage. Out of four wires of telephone only red and green is of our interest. This telephone line powered LED lamp is small, efficient and bright; one can also be use this for study or desk lamp.
Telephone Line Powered LED Lamp  circuit schematics with explanation


Schematic:
Telephone Line Powered LED Lamp  circuit schematics with explanation
Telephone Line Operated LED Lamp
Components Required:
BR2----------------------Bridge Rectifire
U2------------------------LM617T or LM317L
R3-------------------------270 ohm 1/2watt
R4-------------------------6.8k ohm
12 white LEDs

2-25V 5A Power Supply LM338 circuit schematic with explanation

2-25V 5A Power Supply LM338

This power supply circuit uses a LM338 adjustable 3 terminal regulator to supply a current of up to 5A over a variable output voltage of 2V to 25V DC. It will come in handy to power up many electronic circuits when you are assembling or building any electronic devices. The schematic and parts list are designed for a power supply input of 240VAC. Change the ratings of the components if 110V AC power supply input is required.



The mains input is applied to the circuit through fuse F1. The fuse will blow if a current greater than 8A is applied to the system. Varistor V1 is used to clamp down any surge of voltage from the mains to protect the components from breakdown. Transformer T1 is used to step down the incoming voltage to 24V AC where it is rectified by the four diodes D1, D2, D3 and D4. Electrolytic capacitor E1 is used to smoothen the ripple of the rectified DC voltage.

Power supply parts list:


Diodes D5 and D6 are used as a protection devices to prevent capacitors E2 and E3 from discharging through low current points into the regulator. Capacitor C1 is used to bypass high frequency component from the circuit. Ensure that a large heat sink is mounted to LM338 to transfer the heat generated to the atmosphere.

More about 2-25V 5A Power Supply LM338

DA1553CQ - Car Audio Amplifier 2 x 22 Watt Schematic Circuit With explanation


This is a 22 Watt car stereo audio amplifier. The circuit is based by a single IC TDA1553 with some external components, this IC will handle your stereo car audio system. The IC TDA1553CQ contains 2×22 W amplifiers with differential input stages and can be used for bridge applications.. The gain of each amplifier is fixed at 26 dB. The device is primarily developed for car radio applications.
Circuit of  DA1553CQ Car Audio  Amplifier
Circuit of 2 x 22W-BTL Car Audio Amplifier
Using DA1553CQ

 DA1553CQ PinOut DA1553CQ IC Pinning

Note:
  • The DA1553CQ IC must be fitted with adequately sized heat sinks.
  • Connect a 10K POT in series with the input as volume control if you need. Not shown in circuit diagram.
  • Use 12V DC for powering the circuit.

When a short-circuit to ground occurs, which forces a DC voltage across the loudspeaker of >= V, a built-in protection circuit becomes active and limits the DC voltage across the loudspeaker to <= V. Pin 12 detects the status of the protection circuit (e.g. for diagnostic purposes).

If any output is short-circuited to ground during the standby mode, it becomes impossible to switch the circuit to the mute or operating condition. In this event the supply current will be limited to a few milliamps.

Rangkaian Audio Amplifier TDA7295 - 80W Circuit Schematic With explanation

Rangkaian Audio Amplifier TDA7295 - 80W

The following a circuit of 80W audio amplifier is using by IC TDA7295. The circuit very simple and will be easy to build. TDA7295 has many features to support your audio system, the most important is that the IC has wide voltage range, very low distortion and very low noise feature.
Rangkaian Audio Amplifier TDA7295Rangkaian Audio Amplifier TDA7295 - 80W

TDA7295 PinningTDA7295 IC Pinning

Note:
  • The TDA7295 IC must be fitted with adequately sized heat sinks.
  • Power supply voltage should not exceed 40V
  • Connect a 50K POT in series with the input as volume control if you need. Not shown in circuit diagram.

The TDA7295 is a monolithic integrated circuit in Multiwatt 15 package, intended for use as audio class AB amplifier in Hi-Fi field applications (Home Stereo, self powered loudspeakers, Topclass TV). Thanks to the wide voltage range and to the high out current capability it is able to supply the highest power into both 4Ω and 8Ω loads even in presence of poor supply regulation, with high Supply Voltage Rejection. The built in muting function with turn on delay simplifies the remote operation avoiding switching on-off noises.

TDA2052 HiFi Power Amplifier 60W Circuit Schematic With explanation

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This is a circuit of 60 watt HiFi audio amplifier system using IC TDA2052 . The circuit is class AB amplifier which operates split power supply type with a maximum voltage of 25V and generates 60 Watt power output. Heatsink should be installed on the power IC to avoid excessive heat.

Rangkaian 60W HiFi Power Amplifier TDA2052Rangkaian 60W HiFi Power Amplifier TDA2052

TDA2052 Pinout
TDA2052 IC Pinning

The TDA2052 is a monolithic integrated circuit in Heptawatt package, intended for use as audio class AB amplifier in TV or Hi-Fi field application. Thanks to the wide voltage range and to the high out current capability it’s able to supply the highest power into both 4/8 loads even in presence of poor supply regulation. The built in Muting/Stand-by function simplifies the remote operations avoiding also switching on-off noises

Absolute Maximum Ratings of IC TDA2052
DC Supply Voltage                         :  ±25 V
Output Peak Current (internally limited) : 6 A
Power Dissipation : 70°C 30W
Operating Temperature Range : +70 °C
Storage and Junction Temperature : -40 to +150 °C

TDA7383 - Car Quad Audio Amplifier 35W Circuit Schematic With explanation


The following a 4 x 35 watts channels/quad audio power amplifier circuit based IC TDA7383. The amplifier circuit is designed specifically suitable for car audio system applications. With a fairly large output power per channel, low distortion and low output noise features. Heatsink should be installed on the power IC to avoid excessive heat. There are very simple and easy to build cos only a few additional components outside the IC power.

Circuit of  4 x 35W Car  Audio Amplifier TDA7383 Rangkaian 4 x 35W Car Audio Amplifier TDA7383

TDA7383 PinningTDA7383 Pinning

IC TDA7383 is a new technology class AB Audio Power Amplifier in Flexiwatt 25 package designed for high end car radio applications. Thanks to the fully complementary PNP/NPN output configuration the TDA7383 allows a rail to rail output voltage swing with no need of bootstrap capacitors. The extremely reduced components count allows very compact sets. The on-board clipping detector simplifies gain compression operations. The fault diagnostics makes it possible to detect mistakes during Car- Radio assembly and wiring in the car.

Absolute Maximum Ratings of IC TDA7383
Operating Supply Voltage                                   : 18 V
DC Supply Voltage : 28 V
Peak Supply Voltage (t = 50ms) : 50 V
Output Peak Current Repetitive (Duty Cycle 10% at f = 10Hz): 4.5 A
Output Peak Current Non Repetitive (t = 100µs) : 5.5 A
Power dissipation, (Tcase = 70°C) : 80 W
Junction Temperature : 150 °C
Storage Temperature : – 55 to 150 °C

220V AC Ultra Bright LEDs lamp Circuit Schematic with explanation

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220V AC Ultra Bright LEDs lamp Circuit

This ultra-bright white LED lamp works on 230V AC circuit with minimal power consumption. Ultra-bright LEDs available in the market cost Rs 8 to 15. These LEDs emit a 1000-6000mCd bright white light, like the welding arc and work on 3 volts, 10 mA. Their maximum voltage is 3.6 volts and the current is 25 mA. Anti-static precautions taken Pls Should Be handling the LEDs. The LEDs in a water-clear plastic package emit spotlight, while diffused type LEDs have a wide-angle radiation pattern.
220V AC Ultra Bright LEDs lamp Circuit220V AC Ultra Bright LEDs lamp Circuit

The schematics circuit of above employs capacitive reactance for limiting the current flow through the LEDs on the application of mains voltage to the circuit. We use only if a series resistor for limiting the current with mains operation. The 100-ohm, 2W resistor series avoids heavy 'inrush' During current transients. MOV at the input prevents surges or spikes, protecting the circuit. The 390-kilo-ohm, ½-watt resistor acts as a bleeder to Provide discharge path for capacitor Cx Pls mains supply is disconnected. The zener diode at the output section prevents excess levels of reverse voltage appearing across the LEDs During the negative half-cycles. During the positive half cycle, the voltage across the LEDs is limited to the zener voltage.
220V AC Ultra Bright LEDs lamp Circuit16-LED/46-LED combination

Aseries combination of 16 LEDs Gives a luminance (lux) equivalent of a 12W bulb. But if you have two series combinations of 23 LEDs in parallel (Total 46 LEDs), it Gives equal to a 35W light bulb.

Diode D1 (1N4007) and capacitor C1 act as rectifying and smoothing elements to Provide DC voltages to the row of LEDs. For a 16-LED row, use Cx of 12:22 μF, 630V; C1 of 22 μF, 100V; and zener of 48V, 1W. Similarly, for 46 LEDs combination use Cx of 0:47 mF, 630V; C1 of 33 μF, 150V; and zener of 69V, 1W. This circuit (inclusive of LEDs) costs Rs 200 to Rs 400.

Source

4 x 25 W Car Amplifier TDA7381 Schematic Circuit with explanation

4 x 25 W Car Amplifier TDA7381 Circuit

This is a 4 x25 Watt audio amplifier circuit using IC TDA7381. The amplifier circuit require few external components and is very easy to build. This amplifier is designed for car audio system, but you may use the circuit for another application such as mp3 player, computer etc

4 Rangkaian 4 x 25 W Car audio Amplifier
Using TDA7381

TDA7381 IC PinningTDA7381 IC Pinning

Note:
  • The TDA7295 IC must be fitted with adequately sized heat sinks.
  • Use 12V DC for powering the circuit.
  • Connect a 50K POT in series with the input as volume control if you need. Not shown in circuit diagram.
The TDA7381 is a class AB audio power amplifier in Flexiwatt25 package designed for car radio applications. You you can also use this circuit for other purposes. Thanks to the fully complementary PNP/NPN output configuration the TDA7381 allows a rail to rail output voltage swing with no need of bootstrap capacitors.

The extremely reduced components count allows very compact sets. The on-board clipping detector simplifies gain compression operations. The fault diagnostics makes it possible to detect mistakes during Car- Radio assembly and wiring in the car.

Absolute maximum ratings of IC TDA7295 IC
  1. Operating supply voltage = 18 V
  2. DC supply voltage = 28 V
  3. Peak supply voltage (t = 50 ms) = 50 V
  4. Output peak current Repetitive (duty cycle 10 % at f = 10 Hz) = 3 A
  5. Output peak current Non repetitive (t = 100 μs) = 4A
  6. Power dissipation, (Tcase = 70 °C) = 80 W
  7. Junction temperature = 150 °C
  8. Storage temperature = -40 to 150 °C

Sound Operated Switch Circuit Schematic with explanation

Amplifier: TL081 Comparator: TL081 or CA3140

R can be almost any value greater than about 10k. Use a small (low impedance) loudspeaker as a microphone

This circuit must have a 5v regulated supply. This is provided by the 7805 regulator.

The circuit shown above should be sensitive enough to respond to a reasonably loud clap of the hands at a distance of about a metre from the microphone. If the microphone (loudspeaker) is not very close to the circuit board, use screened lead to connect it to the rest of the circuit. If you require greater sensitivity, you can add the simple pre-amp shown below.

Sound Operated switch 4013 B1D78

The sensitivity of the circuit can be adjusted using the variable potential divider connected to the inverting input of the comparator. To set the sensitivity to maximum, connect a voltmeter to the output of the second amplifier and adjust the variable potential divider to the point which just takes the voltmeter reading to its lowest figure (zero for CA3140, about 1·5v for TL081).

Adding this pre-amp to the sound operated switch will make it very sensitive so keep all connecting wires as short as possible.

Source : http://www.saburchill.com/


AVR wireless dimmer Project circuit schematic with explanation

AVR wireless dimmer Project
At first we have to modify the layout of the old Avr dimmer. I don't think the RS232 interface will be used much when we have the wireless option available, so all the parts for the RS232 will have to go, the other thing that we don't really need anymore is the crystal with the 2 capacitors, because the ATtiny2313 has a build in RC clock of 4 and 8 Mhz which is more than sufficient. One more thing that could go is the infrared receiver, but this doesn't take much room on the circuit board so I will leave it on for the moment. The last thing we need to change is the power supply. The iDwaRF module needs between 2.7 to 3.6 Volts. The ATTiny2313 will run on a voltage between 2.7 to 5.5 volts and the infrared receiver needs 2,7 to 5,5 Volts if we use the TSOP 31236. So if we decide on a power supply of 3.3 Volts all the components will be happy.

Changing the voltage from 5 to 3.3 Volts sounds easier then it turned out to be. Negative regulators of -3.3 Volt are rare and if that is not all the Wireless module seems to have a peak current of more than 60 mA. Our old design could only supply an average of 20 mA. Also I want the dimmer to be power efficient, since I might end up with 10 or more dimmers, regulating everything in the house. So I am thinking of a switching regulator. This way we have a very efficient power supply that can temperarely supply higher currents. More will follow. This will need some testing.

At first we have to modify the layout of the old Avr dimmer. I don't think the RS232 interface will be used much when we have the wireless option available, so all the parts for the RS232 will have to go, the other thing that we don't really need anymore is the crystal with the 2 capacitors, because the ATtiny2313 has a build in RC clock of 4 and 8 Mhz which is more than sufficient. One more thing that could go is the infrared receiver, but this doesn't take much room on the circuit board so I will leave it on for the moment. The last thing we need to change is the power supply. The iDwaRF module needs between 2.7 to 3.6 Volts. The ATTiny2313 will run on a voltage between 2.7 to 5.5 volts and the infrared receiver needs 2,7 to 5,5 Volts if we use the TSOP 31236. So if we decide on a power supply of 3.3 Volts all the components will be happy.

Changing the voltage from 5 to 3.3 Volts sounds easier then it turned out to be. Negative regulators of -3.3 Volt are rare and if that is not all the Wireless module seems to have a peak current of more than 60 mA. Our old design could only supply an average of 20 mA. Also I want the dimmer to be power efficient, since I might end up with 10 or more dimmers, regulating everything in the house. So I am thinking of a switching regulator. This way we have a very efficient power supply that can temperarely supply higher currents. More will follow. This will need some testing.




http://domotica.homeip.net/dimmer3.html

IR Light Dimmer v.1 circuit schematic with explanation

IR Light Dimmer v.1
This is a device for adjusting lights in your home with any type of remote controller (tv, dvd, video,…). Today we are using many devices in our homes to improve quality of our life and this is another example on how you can enhance a simple procedure like switching the lights ON/OFF. It may be difficult to many of us to stand up from our chair only to switch lights, so try imagining yourself doing this with your remote controller.



http://www.electronics-lab.com/projects/motor_light/044/index.html

Projects/IR light dimmer v1

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Projects/IR light dimmer v1
This is a very simple IR light dimmer that you will wish to have sooner or later, especially those who are lazy enough to get up and turn off the lights. There are two versions of PCB for two sizes of capacitors, so PCBs are: 32.5 x 26.5mm and 28.5 x 27mm.

Features of current beta version of firmware:
- Soft start (gradually turning on the light bulb)
- Soft down (gradually turning off the light bulb)
- Learning IR codes from RC5 and NEC remotes
- Dimming in 10 levels by using only IR remote
- Previous dimm-level remembering when operating with remote
- Sleep timer in duration of 1.6min for 60Hz version and 2min for 50Hz version
- ON/OFF control with wall pushbutton

http://www.elektronika.ba/617/ir-light-dimmer-v1

High-Speed Leakage Circuit Breaker Circuit

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High-Speed Leakage Circuit Breaker Circuit




The value of R1, R2, C4, and C5 should be chosen in order to keep at least 12V in Vs.
Please connect C4 (>1μF) and C2 (<1μF).
ZCT and load resistance RL of ZCT are connected between input pin 1 and 2.
Protective resistance (RP=100Ω) must be insurted.
RL and amplifier’s output (in Pin 4) regulates sensitivity current
External capacitor C1 between pin 4 and GND is used for noise removal.
Please connect a varistor or a diode (2 pcs.) to ZCT in parallel, because of when large current is grounded in the
primary side (AC line) of ZCT, the following situation can be abandoned: The wave form in the secondary side of
ZCT is distorted and some signals do not appear in the output of amplifier.
Please connect capacitor (about 0.047μF) between pin 6 and pin 7.
Capacitor C6 between pin 1 and GND is about 0.047μF for removing noise.

M54123L
EARTH LEAKAGE CURRENT DETECTOR

DESCRIPTION
The UTC M54123L is a semiconductor integrated circuit with
amplifier for a high-speed earth leakage circuit breaker.
For the amplifying parts of earth leakage circuit breaker, the
UTC M54123L consists of differential amplifier, latch circuit and
voltage regulator.


In normal operating, the UTC M54123L should be connected
to the secondary side of the ZCT (zero current transformers). Here
the ZCT detects leakage current different amplifiers’ both input.
Then the signals which have been amplified are integrated by
an external capacitor. The integrated signal connects to the input
terminal of latch circuit whose output is suitable for the
characteristics of high- speed earth leakage circuit breaker.
Until the input voltage reaches the fixed level, latch circuit
doesn’t become high. Then drives a thyristor which is connected to
latch circuit’s output terminal.


FEATURES
* With good input sensitivity current temperature characteristics
* High input sensitivity :VT=6.1mV (Typ.)
* Only need low external component count
* High noise and surge-proof
* Low power dissipation :PD=5mW (Typ.)
* May be used both as 100V and 200V.
* Wide temperature range : from -20 °C to +80°C


Datasheet
http://www.unisonic.com.tw/datasheet/M54123L.pdf

CAN BUS Interface With Microcontroller by SPI Circuit

CAN BUS Interface With Microcontroller by SPI Circuit



SYSTEM IMPLEMENTATION



MCP2515
Description
Microchip Technology’s MCP2515 is a stand-alone
Controller Area Network (CAN) controller that implements
the CAN specification, version 2.0B. It is capable
of transmitting and receiving both standard and
extended data and remote frames. The MCP2515 has
two acceptance masks and six acceptance filters that
are used to filter out unwanted messages, thereby
reducing the host MCUs overhead. The MCP2515
interfaces with microcontrollers (MCUs) via an industry
standard Serial Peripheral Interface (SPI).

Features
• Implements CAN V2.0B at 1 Mb/s:
- 0 – 8 byte length in the data field
- Standard and extended data and remote
frames
• Receive buffers, masks and filters:
- Two receive buffers with prioritized message
storage
- Six 29-bit filters
- Two 29-bit masks
• Data byte filtering on the first two data bytes
(applies to standard data frames)
• Three transmit buffers with prioritizaton and abort
features
• High-speed SPI™ Interface (10 MHz):
- SPI modes 0,0 and 1,1
• One-shot mode ensures message transmission is
attempted only one time
• Clock out pin with programmable prescaler:
- Can be used as a clock source for other
device(s)
• Start-of-Frame (SOF) signal is available for
monitoring the SOF signal:
- Can be used for time-slot-based protocols
and/or bus diagnostics to detect early bus
degredation
• Interrupt output pin with selectable enables
• Buffer Full output pins configurable as:
- Interrupt output for each receive buffer
- General purpose output
• Request-to-Send (RTS) input pins individually
configurable as:
- Control pins to request transmission for each
transmit buffer
- General purpose inputs
• Low-power CMOS technology:
- Operates from 2.7V – 5.5V
- 5 mA active current (typical)
- 1 µA standby current (typical) (Sleep mode)
• Temperature ranges supported:
- Industrial (I): -40°C to +85°C
- Extended (E): -40°C to +125°C

http://ww1.microchip.com/downloads/en/DeviceDoc/21801d.pdf

ADC AND I/O CAN BUS Circuit schematic with explanation

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ADC AND I/O CAN BUS Circuit


MCP2502X/5X
Description

The MCP2502X/5X devices operate as I/O expanders
for a Controller Area Network (CAN) system,
supporting CAN V2.0B active, with bus rates up to
1 Mb/s. The MCP2502X/5X allows a simple CAN node
to be implemented without the need for a
microcontroller.

The MCP2502X/5X devices feature a number of
peripherals, including digital I/Os, four-channel 10-bit
A/D (MCP2505X) and PWM outputs with automatic
message transmission on change-of-input state. This
includes an analog input exceeding a preset threshold.

Features
• Implements CAN V2.0B
- Programmable bit rate up to 1 Mb/s
- One programmable mask
- Two programmable filters
- Three auto-transmit buffers
- Two message reception buffers
- Does not require synchronization or
configuration messages
• Hardware Features
- Non-volatile memory for user configuration
- User configuration automatically loaded on
power-up
- Eight general-purpose I/O lines individually
selectable as inputs or outputs
- Individually selectable transmit-on-pinchange
for each input
- Four 10-bit, analog input channels with
programmable conversion clock and VREF
sources (MCP2505X devices only)
- Message scheduling capability
- Two 10-bit PWM outputs with independently
programmable frequencies
- Device configuration can be modified via
CAN bus messages
- In-Circuit Serial Programming™ (ICSP™) of
default configuration memory
- Optional 1-wire CAN bus operation
• Low-power CMOS technology
- Operates from 2.7V to 5.5V
- 10 mA active current, typical
- 30 µA standby current (CAN Sleep mode)
• 14-pin PDIP (300 mil) and SOIC (150 mil)
packages
• Available temperature ranges:
- Industrial (I): -40°C to +85°C
- Extended (E): -40°C to +125°C

http://ww1.microchip.com/downloads/en/DeviceDoc/21664D.pdf

MAGNETIC LEVITATION Project & CRITICAL TEMPERATURE KIT

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MAGNETIC LEVITATION Project & CRITICAL TEMPERATURE KIT
ELECTRONICS CIRCUIT SCHEMATIC DIAGRAMS
The following figure is a schematic diagram for the Electronics Board.










Operation of the Electronics Board circuitry may be of interest to some students who use the Levitation/Critical Temperature kit. Individual circuit functions may be understood and analyzed from the following explanations. Operational amplifiers (op amps) are characterized by two nearly ideal properties, which lead to a wide variety of applications. These properties are 1) high impedance between the non-inverting and inverting inputs and 2) high open loop gain. Usually, both of these may be assumed to be infinite. Infinite impedance means no current flows between inputs, and infinite gain means that negative feedback will drive input voltage difference to zero. A variety of circuits can be analyzed using these two properties and Ohm's law.
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Perpetual top Levitation Toy

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Perpetual top Levitation Toy
The point of the perpetual top levitation toy is simply that it continues spinning forever, and the challenge is to understand the driving mechanism. The top is made of plastic, and contains embedded in it a small permanent magnet, oriented perpendicular to the spin axis of the top. The base contains a transistor and a coil with two windings, the assembly being driven by a 9-volt power supply. A schematic of the electrical circuit is shown in the figure.
As one pole of the magnet (say the south pole) approaches the coil, a current in induced in winding A, in such a direction as to make the base of the transistor (an NPN) go positive. That makes the emitter-collector current flow through winding B, in the opposite direction to A. The current through B is larger than that of A (due to the amplification of the transistor), so by Lenz's law the magnet pole will be attracted to the coil.






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