Low Cost Universal Battery Charger Schematic

Low cost solution for charging of both NiCd and NiMh batteries

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Here is the circuit diagram of a low cost universal charger for NiCD – NiMH batteries. This circuit is Ideal for car use. It has ability to transform a mains adapter in to a charger . This one can be used to charge cellular phone, toys, portables, video batteries, MP3 players, … and has selectable charge current. An LED is located in circuit to indicate charging. Can be built on a general purpose PCB or a veroboard. I hope you really like it.

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Picture of the circuit:

A Low Cost Universal Charger Circuit Schematic

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Circuit diagram:

A Low Cost Universal Charger Circuit Diagram

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Parts:

R1 = 120R-0…5W
R2 = See Diagram
C1 = 220uF-35V
D1 = 1N4007
D2 = 3mm. LED
Q1 = BD135
J1 = DC Input Socket

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Specifications:

• Ideal for in car use.
• LED charge indication.
• Selectable charge current.
• Charges Ni Cd or NiMH batteries.
• Transforms a mains adapter into a charger.
• Charge cellular phone, toys, portables, video batteries …

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Features:

• LED function indication.
• Power supply polarity protected.
• Supply current: same as charge current.
• Supply voltage: from 6.5VDC to 21VDC (depending on used battery)
• Charge current (±20%): 50mA, 100mA, 200mA, 300mA, 400mA. (selectable)

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Determining the supply voltage:

This table indicates the minimum and maximum voltages to supply the charger. See supply voltage selection chart below.

Example:

To charge a 6V battery a minimum supply voltage of 12V is needed, the maximum voltage is then 15V.

Voltage selection:

Voltage Selection Chart For Low Cost Universal Battery Charger

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Determining the charge current:

Before building the circuit, you must determinate how much current will be used to charge the battery or battery pack. It is advisable to charge the battery with a current that is 10 times smaller then the battery capacity, and to charge it for about 15 hours. If you double the charge current , then you can charge the battery in half the time. Charge current selection chart is located in diagram.

Example:

A battery pack of 6V / 1000mAh can be charged with 100mA during 15 hours. If you want to charge faster, then a charge current of 200mA can be used for about 7 hours.

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Caution:

The higher charge current, the more critical the charge time must be checked. When faster charging is used, it is advisable to discharge the battery completely before charging. Using a charge current of 1/10 of the capacity will expand the lifetime of the battery. The charge time can easily be doubled without damaging the battery.

Note:

• Mount the transistor together with the heatsink on the PCB, bend the leads as necessary. Take care that the metal back of the transistor touches the heatsink. Check that the leads of the transistor do not touch the heatsink.

Cell Phone Battery Meter 3.6 Volt circuit and explanation

This is a similar circuit to the above and provides a 4 LED bar graph indicating the voltage of a common 3.6 volt Lithium – Ion recharable cell phone battery. The reference voltage is provided by a TL431 programmable voltage source which is set to 3.9 volts where the TL431 connects to the 1K resistor. The lower reference for the LED at pin 14 is set with the 5K adjustable resistor.

The programmed voltage of the TL431 is worked out with a voltage divider (10K 5.6K). The adjustment terminal or junction of the two resistors is always 2.5 volts. So, if we use a 10K resistor from the adjustment terminal to ground, the resistor current will be 2.5/10000 = 250uA. This same current flows through the upper resistor (5.6K) and produces a voltage drop of .00025 * 5600 = 1.4 volts. So the shunt regulated output voltage at the cathode of the TL431 will be 2.5 + 1.4, or 3.9 volts.

Working out the LED voltages, there are three 390 ohm resistors in series with another adjustable (5K) resistor at the bottom. Assuming the bottom resistor is set to 2K ohms, the total resistance is 390+390+390+2000 = 3170 ohms. So, the resistor current is the reference voltage (3.9) divided by the total resistance, or about 3.9/ (390 + 390 + 390 + 2000) equals 1.23 mA. This gives us about .00123*2000= 2.46 volts for the bottom LED, and about .00123*390 = .48 volts for each step above the bottom. So, the LEDs should light at steps of 2.46, 2.94, 3.42, and 3.9. A fully charged cell phone battery is about 4.2 volts. You can adjust the 5.6K resistor to set the top voltage higher or lower, and adjust the lower 5K resistor to set the bottom LED for the lowest voltage. But you do need a 6 to 12 volt or greater battery to power the circuit.

20VAC 60 Watt Sunrise Lamp Circuit

20VAC 60 Watt Sunrise Lamp Circuit

In this circuit, a 120VAC lamp is slowly illuminated over a approximate 20 minute period. The bridge rectifier supplies 120 DC to the MOSFET and 60 watt lamp. A 6.2K, 5 watt resistor and zener diode is used to drop the voltage to 12 volts DC for the circuit power. The bridge rectifier should be rated at 200 volts and 5 amps or more. In operation, a 700 Hz triangle waveform is generated at pin 1 of the LM324 and a slow rising voltage is obtained at pin 8. These two signals are compared at pins 12 and 13 to produce a varying duty cycle rectangular waveform at pin 14, which controls the MOSFET and brightness of the 60 watt lamp. When power is applied, the lamp will start to illuminate within a minute or so, and will slowly brighten to full intensity in about 20 minutes. You can make that longer or shorter with adjustments to the 270K resistor at pin 9. The 2.2 ohm resistor and .015uF cap connected to the lamp serve to supress RFI. The diode at pin 9 and 10K resistor on pin 8 are used to discharge the 3300uF cap when power is removed. Power should be off for a few minutes before re-starting.

Caution: This circuit is connected directly to the AC line and presents a hazard if any part is touched while connected to the line. Use caution and do not touch any parts while the circuit is connected to the AC line. You may want to use a 9 volt battery connected across the 12 volt zener to check the basic operation. The DC voltage at pins 1,2,3,5,6,7 will all be around 4.3 volts if the circuit is working correctly. If the DC voltages are all correct, you can use a variac to slowly apply the full line voltage and check for proper operation.

FET Audio Mixer This simple circuit mixes two or more channels into one channel (eg. stereo into mono). The circuit can mix as many or as few channel

FET Audio Mixer

This simple circuit mixes two or more channels into one channel (eg. stereo into mono). The circuit can mix as many or as few channels as you like and consumes very little power. The mixer is shown with two inputs, but you can add as many as you want by just duplicating the "sections" which are clearly visible on the schematic.

Schematic
Parts

Part Total Qty. Description

R1, R3 2 10K Pot
R2, R4 2 100K 1/4 W Resistor

25W Mosfet audio amplifier -- High Quality simple unit -- No need for a preamplifier Circuit diagram: 25 Watt Amplifier Parts: R1,R4 = 47K 1/4W

25W Mosfet audio amplifier

-- High Quality simple unit
-- No need for a preamplifier


Circuit diagram:

25 Watt Amplifier

Parts:
R1,R4 = 47K

1/4W Resistors
R2 = 4K7 1/4W Resistors
R3 = 1K5 1/4W Resistors
R5 = 390R 1/4W Resistors
R6 = 470R 1/4W Resistors
R7 = 33K 1/4W Resistors
R8 = 150K 1/4W Resistors
R9 = 15K 1/4W Resistors
R10 = 27R 1/4W Resistors
R11 = 500R

1/2W Trimmer Cermet
R12,R13,R16 = 10R 1/4W Resistors
R14,R15 = 220R 1/4W Resistors
R17 = 8R2 2W Resistor
R18 = R22 4W Resistor (wirewound)

C1 = 470nF 63V Polyester Capacitor
C2 = 330pF 63V Polystyrene Capacitor
C3,C5 = 470?F 63V Electrolytic Capacitors
C4,C6,C8,C11 = 100nF 63V Polyester Capacitors
C7 = 100?F 25V Electrolytic Capacitor
C9 = 10pF 63V Polystyrene Capacitor
C10 = 1?F 63V Polyester Capacitor

Q1-Q5 = BC560C 45V100mA Low noise High gain PNP Transistors
Q6 = BD140 80V 1.5A PNP Transistor
Q7 = BD139 80V 1.5A NPN Transistor
Q8 = IRF532 100V 12A N-Channel Hexfet Transistor
Q9 = IRF9532 100V 10A P-Channel Hexfet Transistor

Power supply circuit diagram:

Power supply

Parts:
R1 = 3K3 1/2W Resistor

C1 = 10nF 1000V Polyester Capacitor
C2,C3 = 4700?F 50V Electrolytic Capacitors
C4,C5 = 100nF 63V Polyester Capacitors

D1 200V 8A Diode bridge
D2 5mm. Red LED
F1,F2 3.15A Fuses with sockets

T1 220V Primary, 25 + 25V Secondary 120VA Mains transformer
PL1 Male Mains plug
SW1 SPST Mains switch



Notes:
*Can be directly connected to CD players, tuners and tape recorders. Simply add a 10K Log potentiometer (dual gang for stereo) and a switch to cope with the various sources you need.
*Q6 & Q7 must have a small U-shaped heatsink.
*Q8 & Q9 must be mounted on heatsink.
*Adjust R11 to set quiescent current at 100mA (best measured with an Avo-meter in series with Q8 Drain) with no input signal.
*A correct grounding is very important to eliminate hum and ground loops. Connect in the same point the ground sides of R1, R4, R9, C3 to C8. Connect C11 at output ground. Then connect separately the input and output grounds at power supply ground.

Technical data:
Output power: well in excess of 25Watt RMS @ 8 Ohm (1KHz sinewave)
Sensitivity: 200mV input for 25W output
Frequency response: 30Hz to 20KHz -1dB
Total harmonic distortion @ 1KHz: 0.1W 0.014% 1W 0.006% 10W 0.006% 20W 0.007% 25W 0.01%
Total harmonic distortion @10KHz: 0.1W 0.024% 1W 0.016% 10W 0.02% 20W 0.045% 25W 0.07%
Unconditionally stable on capacitive loads

Low pass filter - Subwoofer The acoustic spectrum is extended by very low frequencies 20Iz and reaches as the 20000Iz in high frequencies. In the lo

Low pass filter - Subwoofer

The acoustic spectrum is extended by very low frequencies 20Iz and reaches as the 20000Iz in high frequencies. In the low frequencies is degraded the sense of direction. This reason us leads to the utilization speaker for the attribution of very low frequencies. The manufacture that to you we propose distinguishes these frequencies, in order to him we lead to the corresponding amplifier. The acoustic filters are met in various points in the sound systems. The knownest application they are the filters baxandal for regulating tone low and high frequencies and filters crossover where the acoustic region is separated in subareas, in order to it leads the corresponding loudspeakers. The application that to you we propose is a simple filter of region that limits the acoustic region (20-20000Hz) in the region 20-100Hz.

With the manufacture that to you we propose you can make a active filter in order to you lead a loudspeaker of very low frequencies. With this you will place one bigger speaker between the HIFI speakers of you. In order to you have a complete picture of sound you will need also the corresponding amplifier. In the entry of circuit you will connect the two exits of preamplifier or the exit of line of some preamplifier. The circuit of manufacture allocates a exit in order to is led means of circuit of force subwoofer. If for some reason you do not have space in order to you place the third speaker in space of hearing, then you can select smaller speaker. The output will depend from the type of music that you hear. If in deed you have space, then after you make a filter and remain thanked, you can him recommend in your friends or still make other same for your friends.

Theoretical circuit

In the form it appears the theoretical circuit of filter. In first glance we see three different circuits that are mainly manufactured round two operational amplifiers. This circuits constitute mixed, amplifier with variable aid and a variable filter. The manufacture end needs a circuit of catering with operational tendency of catering equal with ±12. the operational amplifiers that constitute the active elements for this circuits of are double operational type as the TL082 and NE5532. The operational these amplifiers belong in a family provided with transistor of effect of field IFET in their entries. Each member of family allocates in their circuit bipolar transistor and effect of field. This circuits can function in his high tendency, because that they use transistor of high tendency. Also they have high honor of rhythm of elevation (slew rate), low current of polarization for the entries and are influenced little by the temperature. The operational these amplifiers have breadth of area unity gain bandwidth 3MHz. A other important element for their choice is the big reject of noise, when this exists in the line of catering.

The price of reject is bigger than 80dB, their consumption is small, from 11 until 3 mA. They are internally sold in nutshell with eight pins and allocate two operational amplifiers, In the same line in nutshell 14 pins they incorporate four operational, In the trade they are sold with code TL074, TL084 and TL064, In nutshell with eight pins they are sold operational amplifiers TL061 TL071 kajTL081. In the manufacture we used the TL082 that has two operational. First operational from the TL082 it works as amplifier and mixed for the two channels, In his negative entry he exists one small mixed with two resistances. A potentiometer in this rung determines the aid of circuit. In the point this left winger and the right channel of preamplifier they are added means of two resistances. En continuity the operational strengthens signal with aid made dependent from the price that has the potentiometer.

The place of runner is proportional with the aid of circuit. The second operational amplifier is the filter of manufacture. The filter of is acoustic frequency of second class and he is made with the materials that are round the operational amplifier. The filter of is low passage with variable frequency of cutting off. This frequency can be altered and take prices from very low frequency the 30Hz or still exceed 150Hz. The frequency of cutting off of filter depends from the prices that have the elements of circuit. Altering the values of elements we can have frequency of cutting off 150Iz, 130Iz, J00Iz, 7Ïz, 6Íz even 3Íz, this prices they can be achieved with the simple rotation of double potentiometer. The circuit of filter has been made around one operational' that it has completed TL082 that is double operational amplifier. In the exit of filter we will link the plug of expense where is connected the amplifier. In the exit of circuit is presented, the limited as for the breadth of frequencies, signal that we apply in the entry of circuit.

Manufacture Parts

R1 = 39 Kohm R2 = 39 Kohm
R3 = 47 Kohm R4 = 10 Ohm
R5 = 22 Kohm R6 = 4,7 Kohm
R7 = 22 Kohm R8 = 4,7 Kohm
R9 = 10 Ohm R10 = 220 Ohm
C1 = 39 pF C2 = 0.1 uF
C3 = 0.1 uF C4 = 0.2 uF
C5 = 0.4 uF C6 = 0.1 uF
C7 = 0.1 uF IC1 = TL064

In order to you make the manufacture you will need printed that appears in the form. In this you will place the materials according to the following form. The materials are enough also easy can become certain errors. With few attention however you can him avoid. If they are presented difference malfunctions, you check carefully the circuit. The circuit, as we said, is filter and it should they are used materially good precision and quality, particularly for the capacitors. The capacitors of filters will have tolerance 5%. Of course, the manufacture will also work with material of lower quality, the trial of manufacture can become with acoustic signal of generator We apply the generator in the entry of manufacture and we measure with a voltmeter the tendency in the exit of filter. If we alter the potentiometer and are altered the tendency, then all have well.

3 Watt FM Transmitter This is the schematic for an FM transmitter with 3 to 3.5 W output power that can be used between 90 and 110 MHz. Although the

3 Watt FM Transmitter

This is the schematic for an FM transmitter with 3 to 3.5 W output power that can be used between 90 and 110 MHz. Although the stability isn't so bad, a PLL can be used on this circuit.

Schematic
This is the schematic of the 3W FM Transmitter

Parts

Part Total Qty. Description Substitutions
R1,R4,R14,R15 4 10K 1/4W Resistor
R2,R3 2 22K 1/4W Resistor
R5,R13 2 3.9K 1/4W Resistor
R6,R11 2 680 Ohm 1/4W Resistor
R7 1 150 Ohm 1/4W Resistor
R8,R12 2 100 Ohm 1/4W Resistor
R9 1 68 Ohm 1/4W Resistor
R10 1 6.8K 1/4W Resistor
C1 1 4.7pF Ceramic Disc Capacitor
C2,C3,C4,C5,C7,
C11,C12 7 100nF Ceramic Disc Capacitor
C6,C9,C10 3 10nF Ceramic Disc Capacitor
C8,C14 2 60pF Trimmer Capacitor
C13 1 82pF Ceramic Disc Capacitor
C15 1 27pF Ceramic Disc Capacitor
C16 1 22pF Ceramic Disc Capacitor
C17 1 10uF 25V Electrolytic Capacitor
C18 1 33pF Ceramic Disc Capacitor
C19 1 18pF Ceramic Disc Capacitor
C20 1 12pF Ceramic Disc Capacitor
C21,C22,C23,C24 4 40pF Trimmer Capacitor
C25 1 5pF Ceramic Disc Capacitor
L1 1 5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L2,L3,L5,L7,L9 5 6-hole Ferroxcube Wide band HF Choke (5 WDG)
L4,L6,L8 3 1.5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L10 1 8 WDG, Dia 5 mm, 1 mm CuAg, Space 1 mm
D1 1 BB405 BB102 or equal (most varicaps with C = 2-20
pF [approx.] will do)
Q1 1 2N3866
Q2,Q4 2 2N2219A
Q3 1 BF115
Q5 1 2N3553
U1 1 7810 Regulator
MIC 1 Electret Microphone
MISC 1 PC Board, Wire For Antenna, Heatsinks

Notes

1. The circuit has been tested on a normal RF-testing breadboard (with one side copper). Make some connections between the two sides. Build the transmitter in a RF-proof casing, use good connectors and cable, make a shielding between the different stages, and be aware of all the other RF rules of building.

2. Q1 and Q5 should be cooled with a heat sink. The case-pin of Q4 should be grounded.

3. C24 is for the frequency adjustment. The other trimmers must be adjusted to maximum output power with minimum SWR and input current.

4. Local laws in some states, provinces or countries may prohibit the operation of this transmitter. Check with the local authorities.

Allpass network shifts signals 90° Unlike lowpass, bandpass, and other magnitude-altering filters, allpass filters can shift the phase of a signal wi

Allpass network shifts signals 90°

Unlike lowpass, bandpass, and other magnitude-altering filters, allpass filters can shift the phase of a signal without affecting its amplitude. For a first-order allpass circuit, the transfer function is
As you sweep the variables from zero (dc) to infinity, the sign of H(s) changes from plus to minus, indicating a change in phase from 0 to 180°. You can realize this transfer function in two wideband transconductance amplifiers (WTAs). The circuitry inside the dashed lines in Fig 1 is one allpass network.

A WTA's transfer function is IOUT8VIN/Z, where 8 is simply an internal constant and Z is an external gain-setting component connecting the WTA's Z+ and Z- pins. The transfer function for voltage amplification is VOUT/VINIOUTxZOUT. Most applications require a resistive Z. But the WTA also accepts an inductor, a capacitor, or any other impedance network for Z.

The allpass circuit combines a resistive-Z WTA (IC1) with a capacitive-Z WTA (IC2). At low frequencies, IC1 dominates the circuit's output because the capacitor's high impedance allows only a low IOUT from IC2. Rising frequencies lowers this impedance, causing the current from IC2 to dominate at high frequencies. Moreover, IC2 inverts, and IC1 does not, producing the desired noninverting unity gain at dc and inverting unity gain at high frequencies.

Communications and signal-processing applications use allpass networks widely. An example is a 90°-phase-shift network, which, with appropriate mixers, produces a single-sideband signal. In Fig 1, the two allpass circuits have corner frequencies that differ by a factor of 7.5. The output RC networks determine these corner frequencies. The result is an output-phase difference that remains close to 90° over a wide frequency range. Measurements show 0.2-dB amplitude variations and a phase difference of 90°±7° from 180 to 740 kHz-a 4:1 range. (DI #1696)

Two wideband transconductance amplifiers (WTAs) form an allpass network (within dashed lines). Combining two such networks produces two outputs having a constant 90° phase shift versus frequency between them.

Quadraphonic Amplifier Description: This is a four channel amplifier ideally suited for use with quadraphonic equipment such as a Sound Blaster Liv

Quadraphonic Amplifier


Description:

This is a four channel amplifier ideally suited for use with quadraphonic equipment such as a Sound Blaster Live card. There is no volume control,audio levels being directly controlled from the sound card itself.

circuit:


Parts List:
D1-D4: 1N4001 (4)
C1,C20: 1000u CAP (2)
C2,C11: 47u CAP (2)
C3,C5,C7,C8,C12,C14,C16,C17,C21,C22: 0.1u CAP (10)
C4,C6,C13,C15: 10u CAP (4)
C9,C10,C18,C19: 2200u CAP (4)
R1,R4,R9,R12: 1M RESISTOR (4)
R2,R6,R10,R14: 100k RESISTOR (4)
R3,R5,R11,R13: 1k RESISTOR (4)
R7,R8,R15,R16: 2R7 RESISTOR (4)
IC1: 7812 (1)
IC2,IC3: LM1778N (2)
SPK1,SPK2,SPK3,SPK4: 8R 2 Watt speakers (4)

Notes:

Construction is straight forward and is suitable for Verobaord. Overall gain is controlled by the ratio R14/R13 and R6/R5. Used with small hi-fi speakers the volume was too loud for my room so I reduced R14 and R6 to 33k. The zobel network formed by R7,C7,R8,C8,R15,C16,R16,C17 prevents instability which can happen with long speaker wires. The input impedance is high, 1M and if very long input cables are present could pick up noise. Screened cable should be used, in my case I used 10k resistors between points A & C, B & C, D & F, E & F. This provides a DC path to ground and higher noise immunity. If instability does occur, then you will notice sound distortion and the LM1877N will become hot to touch.

Connections:

The back of a sound blaster live card has color coded 3.5mm stereo jacks. The image below shows a close up of the rear of my Sound Blaster Live card. As well as color coding, each connector has an appropriate marking, for easy connectivity.

The normal output connector is green and the rear speaker connector is black. Creative provide utilities and sound mixer for use with Windows. Under Linux the utility Gamix can be used, which allows independent volume control for all channels.

200W Audio Amplifier circuit and explanation

200W Audio Amplifier

Single Chip 50 Watt / 8 Ohm Power Amplifier

Single Chip 50 Watt / 8 Ohm Power Amplifier
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Circuit Description
There are many instances where a simple and reliable power amplifier is needed - rear and centre channel speakers for surround-sound, beefing up the PC speakers, etc.
This project (unlike most of the others) is based almost directly on the "typical application" circuit in the National Semiconductor specification sheet. As it turns out, the typical application circuit is not bad - would I go so far as to say hi-fi in the audiophile sense? Perhaps - with caveats. It has good noise and distortion figures, and is remarkably simple to build if you have the PCB.
26 Sept 2000
From testing the prototype boards, I was a little more critical of everything. The sound quality is excellent! As long as the protection circuitry is never allowed to operate, the performance is exemplary in all respects.
The ESP version of the circuit has connections for a SIM (Sound Impairment Monitor), and if the amp is going to be used anywhere near its limits, I strongly recommend that you use the add-on SIM circuit. I will eventually simplify the "simple" version of the SIM so that it can be used more easily for exactly this purpose.
Figure 1 shows the updated schematic - this is almost the same as in the application note (redrawn), polyester bypass capacitors have been added, and the mute circuit has been disabled (this function would more commonly be applied in the preamp, and is not particularly useful anyway IMHO).

Figure 1 - LM3876T Power Amplifier Circuit Diagram
Voltage gain is 27dB as shown, but this can be changed by using a different value resistor for the feedback path (R3, currently 22k, between pins 3 and 9). The inductor consists of 10 turns of 0.4mm enamelled copper wire, wound around the body of the 10 Ohm resistor. The insulation must be scraped off each end and the wire is soldered to the ends of the resistor.
The 10 Ohm and 2.7 Ohm resistors must be 1 Watt types, and all others should be 1% metal film (as I always recommend). All electrolytic capacitors should be rated at 50V if at all possible, and the 100nF (0.1uF) caps for the supplies should be as close as possible to the IC to prevent oscillation.
The supply voltage should be about +/- 35 Volts at full load, which will let this little guy provide a maximum of 56 Watts (rated minimum output at 25 degrees C). To enable maximum power, it is important to get the lowest possible case to heatsink thermal resistance. This will be achieved by mounting with no insulating mica washer, but be warned that the heatsink will be at the -ve supply voltage and will have to be insulated from the chassis. For more info on reducing thermal resistance, read the article on the design of heatsinks - the same principles can be applied to ICs - even running in parallel. I haven't tried it with this unit, but it is possible by using a low resistance in series with the outputs to balance the load.


Figure 2 - IC Pinouts
Figure 2 shows the pinouts for the LM3876, and it should be noted that the pins on this device are staggered to allow adequate sized PCB tracks to be run to the IC pins. The 3886 has (almost) identical pinouts, and can be used instead if a little more power is required.

If the LM3886 is used, Pin 5 must be connected to the +ve supply - if you have the PCB, a link is necessary to make the connection, as it is not provided on the board.
The PCB for this amp is for a stereo amplifier, is single sided, and supply fuses are located on the PCB. The entire stereo board including four fuses is 115mm x 40mm (i.e. really small).

To reiterate a point I have made elsewhere, never operate this amp without a heatsink (this applies to nearly all amplifiers). It will overheat very quickly, and although the internal protection will shut the amp down to protect it from damage, this is not something you want to test for no good reason.
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How Does It Sound?
The sound quality is very good - as I said at the beginning, I would call it audiophile hi-fi - with caveats. Provided the amp is never allowed to go anywhere near clipping it sounds very good indeed. This is the rub - because of the comprehensive overload protection (which I have never liked in any form) this amp provides more and nastier "artefacts" as it clips than a "normal" amplifier.
The protection circuitry is called SPiKe™ by National - this stands for Self Peak instantaneous Temperature (°Ke) (sic) and will protect the amp from almost anything. Although in theory this is a good thing, it's not so good when the protection circuits operate, so make absolutely sure that the amp is only used in applications where clipping will never occur, or is relatively lightly loaded.
This might sound like a tall order, but for rear speakers in a surround system, or to put some serious grunt into those 400W PMPO PC speakers (with the 5W RMS amplifiers - I'm not kidding), this amp is a gem.
It could also be used as a midrange and/or tweeter amp in a tri-amped system - there are a lot of possibilities, so I will leave it to you to come up with more.

Loudspeaker Protection with Soft Start circuit and explanation

Loudspeaker Protection with Soft Start


This is a small protection circuit from loudspeakers, from DC voltage that likely to exist after some damage in the power amplifier. If a DC voltage is presented in the exit of amplifier, RL1 it interrupts immediately the line of loudspeakers preventing thus to reach in he. Parallel it provides a delay time of 3 seconds from the moment where the power supply will be applied. This delay protects the loudspeakers from undesirable bangs that are observed when open the supply switch. The Leds D 4-5 provide a optical indication for the circuit operation [D4 (green)=OK and D5(red)= delay or presence DC voltage]. The supply of circuit becomes from a symmetrical ?12Volts, which we can take from small independent power supply or from afterwards suitable demotion of main power supply. It will be supposed you make a circuit of protection for each final amplifier that you dispose. Proportional attention it should you show for the quality of RL1 that the contacts of will be supposed to bear the current that passes from he.

Part List
R1=22Kohm
R2-3=390Kohm
R4=470Kohm
R5=1Mohm
R6-7-8-9-10-12=10Kohm
R11=820 ohm
RL1=Relay 12VDc Omron G2R2
C4-5=100uF 25V
C1-2-3=47uF 63V

IC1=TL071
Q1=BC560C
Q2-3-4=BC550C
Q5=BD139
D1-2-3=1N4148
D4=Green 5mm Led
D5=Red 5mm Led

J1=3pin connector with 2.54mm step
J2=2pin connector with 2.54mm step
J3=2pin connector with 3.96mm step

DC Protection / Time Delay for Loudspeaker circuit and explanation

DC Protection / Time Delay for Loudspeaker

A exceptionally useful circuit for all the final amplifiers, but also in other applications that we needed some time delay and protection DC. The particular circuit combines enough operations, as: [ 1 ] Smooth departure of benefit of AC line of network, with delay 1sec, to the transformers of power supply of amplifier, via the RL1 and the resistance Rx. (see block diagram). [ 2 ] Delay of connection of expenses of final amplifiers, in headphone, in order that noises emanating from the charge - uncharged of capacitors of power supply, they do not pass in them. Simultaneously becomes control of exit of amplifiers for existence of continuous voltage [DC]. If all go well it connects, the amplifiers in loudspeaker. At the duration of operation of amplifiers, exists continuous control, for DC voltage in the exit of amplifiers, unplug him loudspeaker, if is presented problem ph. "opens" some transistor in the final stage and passes the voltage of supply to loudspeaker. [ 3 ] Clue of situation ERROR, optically with the LD3 (can is flash led) and soundly with buzzer (BZ). [ 4 ].
A other operation that exists and with difficulty will find in proportional circuits, is also the existence second relay (RL3), with parallel contacts in the main relay (RL2), connection the loudspeaker in the amplifiers, that it little closes afterwards the RL2. The idea I add one still relay, was supported in the problems that exist, after frequent use of RL2, his contacts are degraded by the electric arcs that are created when it opens and closes relay. Result is a spectrum of frequencies, because the high resistance that is developed in the contacts, the sound of be degraded.
This problem is untied to a large extent, if are added, other contacts at the same time with first, that would close after them, remaining thus clean, one and are not created, on them, differences of potential, so that they are degraded. The circuit can work excellently also in actively loudspeaker one and the circuits of detection DC, afterwards the J2, can make so much all loudspeakers we have. In this case, they will need so much circuits of protection, that actively loudspeaker, we have. In the BLOCK diagram I give a flavour of typical connections, that can become, when the circuit use in stereo amplifier and his supply are taken from main power supply his.
How it works.
The supply of circuit becomes from a AC line in the J1. This voltage can be from a separate transformer 2X12V (the prices of materials that I give it is for 2X12V AC), from existing coil 12V in their M/T of power amplifier or if it cannot become somebody from the two, then from the coils of mainly supply final amplifier, adapting always the prices of resistances R1/2 and R3, proportionally the price of voltage that is supplied the amplifier, according to the law of Ohm and the fall of voltage that we want to achieve (R=V/i). The voltage that it should we have in point A, before the IC2, should is bigger than + 15V 200mA, the IC2 supplies all the relay and led. The remainder circuit is supplied by the R3/D9. When we supply the amplifier with voltage of network (220V AC), charge the C6 via the R4, the price in the entry of IC1a is (H) exit (L) Q1- RL1, is in cutting off. In line with being first the M/T of power supply, intervenes the RX, which ensures smooth connection the M/T in the network, avoiding the burn of fuses, specifically if the force power supply, is big. After 1sec after charge the C6, his negative pole goes to 0V, the entry of IC1A becomes 0V (L), conduct Q1 closes the RL1, short the resistance RX and all the voltage of network is applied in the M/T. Simultaneously turns on LD 1. Via the R5 charge slow the C7 (~5sec), when charge the situation in the pin5 of IC1b become (H), (the other are already (H) from the R23), exit is (L) and the exit of IC1C (H), the Q2 drive the RL2, giving the output of amplifiers in loudspeaker. Simultaneously via the R13 charge the C8 (~2 sec). Hardly charge the C8, conduct the Q3 and close the contacts of RL3, at the same time with those of RL2. The circuit is in complete operation. If we interrupt the line of network all the supply?s fall very fast, with result all relay is cut off, very rapidly cut off, him loudspeakers. If are presented some continuous voltage in entries J2/1 and J2/4, the two circuits of detection DC, then the Q5 or Q6 conduct and lead the entry of IC1b to pin 5 to 0V (L), with result the exit is become (H), the exit of IC1c to be become (L), transistors Q2-3 are cut off and away also the RL2-3 to open, disconnect, him loudspeakers, from the output of amplifiers, until is raised the cause of presence DC.. The same time the exit of IC1D, becomes (H), Q4 conduct, the buzzer [BZ] sounds and turns on the LD3, signaling error. The intensity of sound of BZ, can be regulated from the TR1, but it can it is suppressed if we do not want sound clue of error. The prices of times can change, if are changed capacitors C7-8, with different capacity. Resistances R1-2 if use finally, R3 and R?, should be in some distance from pcb, one and likely hot. The IC2 should enter on heatsink, specifically if the voltage of entry exceeds the +15V. Big attention it should we give in the circuit round resistance RX/CX and the contacts of RL1, because the voltage of network is dangerous (DANGER of ELECTROCUTION). For this reason good it is insulation. What it should we are careful is the quality of all relay, is very good and from known constructor.
R1-2=See text*
D1-4= 1N4007
R3=470R 1W*see text
D5-8= 1N4148
R4-5= 1M D9=12V 1.2W Zener
R6-7= 1K D10-22= 1N4148
R8-14= 15K LD1-2= LED
R9-15= 56K LD3=Flash Led [RED]
R10-16= 56K BZ= BUZZER 12V
R11-17= 10K J1-4= Connectors
R12-13= 39K TR1= 10K Trimmer
R18= 39K RL1-3= 12V 2X2(10A)RELAY
R19= 1K2
R20= 1K
R21-22= 3K9
R23= 22K
R24= 39K
RX= 47R 10W
C1= 220uF 63V
C2-5= 47uF 63V
C3-4=100nF
C6= 1uF 25V
C7= 4.7uF 25V
C8= 470uF 16V
C9-14= 22uF 16V
C10-13= 33uF 63V
CX= 33nF 630V
IC1= 4093 cmos

IC2= 7812T
Q1-4= BD679
Q5-6= BC550C

Linear FM 30Watt circuit and explanation

Linear FM 30Watt

A amplifier of medium force RF for the FM, is always essential for the amateur that wants it strengthens some small transmitter, that likely it has already it manufactured! The present circuit can give force 25-30W, with control no bigger than 4-5 W.

As it appears in the analytic drawing, the amplifier is manufactured with the transistor TR1 of type ?LY89 of Phillips. The transistor this is specifically drawn for operation in frequencies up to 175?hz, with very good results. His special characteristics appear below:
· Tendency of operation: 18V
· Current of Collector: max 3 5th
· Gain: max 10dB
· Force of Expense: 25-30 W
· Output (order C): > 60%

Variable capacitors C1, C2, with inductor L1, constitute the coordinated circuit that adapts the exit of our transmitter in this amplifier RF. the circuit has been calculated suitably, so that it covers all band the FM with the biggest possible output. Inductor RFC1 polarize the transistor, so as to it works in order C that is to say with the biggest output. Inductor L2 in the collector of TR1, constitutes the charge of amplifier, while RFC2 prevents the RF signals escape in the line of catering. Capacitor C2 and resistance R1, protect the circuit from auto polarize.

The coordinated circuit of expense that is constituted by inductor L2 and variable capacitors C3, C4, adapts the exit of amplifier RF with the next stage that can be some amplifier RF of high force (> 100W) or a aerial.

MANUFACTURE

The manufacture of amplifier is very simple and easy. Puncture the point PCB that will pass the nutshell of TR1. Stick the capacitors, variable, the resistance, the RF tsok and the inductors. Finally you stick the TR1, being careful not overheats at the welding and blend pin his. Clean finally PCB from the residues of soldering. Make a very careful control for by any chance errors, omissions, short-circuits, chills you stick also anything other that could you make wonder why does not work the amplifier.

PARTS
C1, C2, C3, C4 = 10 ? 80pF
C 5 = 10nF
C6 = 1000pF
C7 = 100nF
C8 = 2200mF/35V
L1 = 1 coil with diameter of 10 mms, 1 mm
L2 = 7 coils with diameter of 10 mms, 0,8 mm
L3 = 3 coils with diameter of 10 mms, 1 mm
TR1 = BLY89
RFC = RF tsok

If all they are it includes, you connect the exit of your transmitter (3-4W) in the entry of amplifier. The exit of amplifier him you will connect in some charge (dummy load) or in the aerial, through a bridge stagnant. Be supplied with tendency 11-15V your amplifier. (Power supply it should it provides current 45th). Regulate the 4 variable (C1-C4, until you take the biggest force of expense. The amplifier is ready.

Note: The TK1 needs a wiper of dimensions 5x10cm for trouble free operation. This wiper screw in the TR1 without isolators, after his central screw has electric isolation from remainder pins.