This is a variable power supply controlled with PIC microcontroller. There is LCD display in this circuit which will show the actual value of power supply output. This power supply use push on switch to adjust the output voltage and current value.

Schematic Diagram:

Component List:
C1 = 2000uF per AMP, 40V (adjust capacity to power supply amps)
C2,C3,C12,C15,C18,C21 = 0.1uF CER
C4 = 0.01uF CER
C5A,C5B,C5C,C5D = 0.01uF CER
C6,C7 = 0.05uF CER
C8 = Not used
C9,C11,C19,C20 = 1uF CER
C10 = 470uF 15V EL RADIAL
C13 = 4.7µF 50V EL RADIAL
C14 = 0.001uF CER
C16,C17 = 22pF CER

D1,D2,D4,D5 = 1N4148
D3 = 1N4004
Br1 = 1<10A BRIDGE RECTIFIER (adjust seize to power supply amps)
DZ1 = 1N4751 30V ZENER
IC1 = LM317KCS TO220
IC2 = LM337LZ TO92
IC3 = LT1491CN special HV opamp, do not substitute
IC4 = PIC16F876A
Q1 = 2N3906
Q2A to Q2D = TIP142TU 1 to 5 transistors (adjust quantity to power supply amps)
Q3A to Q3D = 2N3904 (adjust quantity to power supply amps)

X1 = 20 mHz HC49 DigiKey PN: 300-6042-ND

LED1 = T1 3/4 RED OR GREEN LED
LCD = LCD, 2X16, HD44780 intelligent controller DigiKey PN: 67-1758-ND insulate from case

P1 = 500 Ohms
P2 = 10 kOhms
P3,P4 = 5 kOhms

R1 = 1 kOhms 10W
R2 = 1.5 kOhms
R3,R11,R12,R13,R14,R16,R17,R25,R26,R27 = 10 kOhms
R4 = 56 Ohms
R5A to R5D = 0.22 Ohms (adjust quantity to power supply amps)
R6,R28,R29 = 47k Ohms
R7 = as per schematic (adjust value to power supply amps)
R8 = 240 Ohms
R9 = 270 Ohms
R10 = 390 Ohms
R15 = 39 kOhms
R18 = 39 kOhms
R19 = 8.2 kOhms
R20,R22,R23,R32 = 1 kOhms
R21 = 5.6 kOhms
R24 = 33 Ohms 1/2W
R30,R31 = 4.7 kOhms

SW1 = SPST min toggle
SW2,SW3,SW4,SW5,SW6,SW7,SW8,SW9 = NO_SP push button
T1 = 24 V 1<8A (adjust seize to power supply amps)
T2 = 6.3 V, 150 mA

MISC:
3 Terminals
Transistors Heat Sink, up to: 1A = 30W, 2A = 60W, 4A = 120W, 8A = 240W to dissipate
Line filter, Case PCB, IC sockets…

PCB Layout:
Top side:

Bottom Side:

SPECIFICATIONS

VOLTAGE:

• Ajustable from 0 < 25 Volts at a resolution of 100 mV.

CURRENT: choice of 4 ranges;

• 0 < 1.000A at a resolution of 1 mA. JP1 and JP2 open, C1 = 2000uF filter cap., R7 = 0.5 Ohm, T1 = 24V, 1Amp.
• 0 < 2.000A at a resolution of 2 mA. JP1 ground and JP2 open, C1 = 4000uF filter cap., R7 = 0.25 Ohm, T1 = 24V, 2Amp.
• 0 < 4.000A at a resolution of 4 mA. JP1 open and JP2 ground, C1 = 8000uF filter cap., R7 = 0.125 Ohm, T1 = 24V, 4Amp.
• 0 < 8.000A at a resolution of 8 mA. JP1 and JP2 ground, C1 = 16000uF filter cap., R7 = 0.0625 Ohm, T1 = 24V, 8Amp.

2 lines LCD display:

• The top line shows the settings, the maximum current stays displayed at all times, it is not necessary to short the output terminals to set the maximum current.
• The bottom line shows the measured values.
• The arrows at the bottom center line show who is in control, the voltage or the current.

Adjustments:

• Voltage, steps of 1 V and 0.1 V.
• Current, steps of 1, 2, 4, 8 mA and 50, 100, 200, 400 mA depending on the Amp range.
• Memorisation of the last settings before power off, restarting with thoses same settings.

Download the full document include schematic diagram, reference, pcb layout and program source code HERE

This is the curcuit application of power amplifier IC LM4756. The IC have the capability to deliver dual output channel at 7W for each channel. Like the other audio amplifier circuits, this circuit just need a few external components to work.

Circuit application:

PCB design:

About LM 4756:

The LM4756 is a stereo audio amplifier capable of delivering 7W/channel at 10% distortion into a 4Ω or 8Ω load. The power amp has an internally set gain of 30dB. A 0V–5V DC controlled volume block provides 80dB of attenuation from input to line-out. Line outputs are available after the volume control for signal routing.

The amplifier has a smooth transition fade-in/out mute and a power conserving standby function which are controlled through TTL or CMOS logic. Both functions provide over 75dB of attenuation.

The LM4756 maintains an excellent Signal-to-Noise ratio of greater than 70dB with a low noise floor less than 2mV. The IC also maintains above 50dB of channel separation.

Features

• Quiet fade-in/out mute function
• Stereo variable line-out pins
• AC output short circuit protectio
• Thermal shutdown protection

Download Datasheet LM4756 for detailed explanation about LM4756 include the circuit application.

This is another power amplifier circuit with power IC KA series. This amplifier delivers dual power output (stereo) at 1.2W for each channel.

The KA2214 is a monolithic integrated dual audio power amplifier in a 14-pin plastic dual in line package. It is designed portable audio sets.

Download the KA2214 datasheet

This is a stereo power amplifier based on Samsung IC KA2211. With single chip, this circuit will deliver up to 5.8W on each output channel.

KA2211 is a dual audio power amplifier for consumer application. It is designed for high power, low dissipation dan low noise. Is also contains various of protectors and suitable for car audio power amplifier with high performance.

Download IC KA2211 datasheet

This is a Hi-Fi power amplifier circuit build based on single power amplifier IC TDA2040. The single TDA2040 has able to deliver 20W power output. The bridge amplifier which consist of double TDA2040 can deliver 30W power output (8 ohm loudspeaker).

About power amplifier IC TDA2040:

The TDA2040 is a monolithic integrated circuit in Pentawatt  package, intended for use as an audio class AB amplifier. Typically it provides 22W output power (d = 0.5%) at Vs = 32V/4W . The TDA2040 provides high output current and has very low harmonic and cross-over distortion. Further the device incorporates a patented short circuit protection system comprising an arrangement for automatically limiting the dissipated power so as to keep the working point of the output transistors within their safe operating area. A thermal shut-down system is also included.

PCB layout for this circuit:

This circuit required split power supply, you may build this power supply circuit diagram to run your amplifier:

There is more amplifier circuits with TDA2040 in TDA2040 datasheet.
Download the TDA2040 datasheet

This is a high power amplifier based on single Sanyo integrated circuit STK-0060II.

STK-0060II Features:

• IMST system
• Dual power supply
• Darlington pure complementary circuit
• Metal substrate used IMST^c makes good thermal stability

Download STK-0060II datasheet include the application circuit

Here the 50W AF power amplifier circuit powered with single IC STK4036II. Use heatsink to prevent overheating on the IC.

STK4036II features:
• Compact package for thin-type audio sets
• Member of pin-compatible series with outputs of 20 to 200W
• Easy heatsink design to disperse heat generated in thintype stereo sets
• Constant-current circuit to reduce supply switch-on and switch-off shock noise
• External supply switch-on and switch-off shock noise muting, load short-circuit protection, thermal shutdown and other circuits can be tailor-designed.

Download STK4036II datasheet HERE

This is a motor speed controller circuit diagram built based Maxim MAX4295. This with this circuit you will be able to control the speed of motor rotation.

Resistor R1 biases the potentiometer to match the input range of U1. Full counter-clockwise rotation of the pot corresponds to maximum-speed reverse rotation of the motor. Mid-scale on the pot corresponds to motor off, and full clockwise rotation of the pot produces maximum-speed forward rotation in the motor.

Download more explanation in PDF version HERE

Here the another amplifier circuit with single power IC from Phillips, TDA1514A. This is a hi-fi power amplifier circuit with 50W power output.

The TDA1514A integrated circuit is a hi-fi power amplifier for use as a building block in radio, tv and other audio applications. The high performance of the IC meets the requirements of digital sources (e.g. Compact Disc equipment).

The circuit is totally protected, the two output transistors both having thermal and SOAR protection (see Fig.3). The circuit also has a mute function that can be arranged for a period after power-on with a delay time fixed by external components.

The device is intended for symmetrical power supplies but an asymmetrical supply may also be used.

TDA1514A Features:
· High output power
· Low harmonic distortion
· Low intermodulation distortion
· Low offset voltage
· Good ripple rejection
· Mute/stand-by facilities
· Thermal protection
· Protected against electrostatic discharge
· No switch-on or switch-off clicks
· Very low thermal resistance
· Safe Operating Area (SOAR) protection.

Download the datasheet of TDA1514A HERE

This is a stereo audio amplifier circuit which will deliver 12W audio power output on each channel. This circuit built based on single IC TDA1521 or TDA1521Q, supported with a few external components.

The TDA1521/TDA1521Q is a dual hi-fi audio power amplifier encapsulated in a 9-lead plastic power package.
The device is especially designed for mains fed applications (e.g. stereo tv sound and stereo radio). A heatsink is required to prevent IC overheating.

TDA1521 Features

• Requires very few external components
• Input muted during power-on and off
• (no switch-on or switch-off clicks)
• Low offset voltage between output and ground
• Excellent gain balance between channels
• Hi-fi according to IEC 268 and DIN 45500
• Short-circuit-proof
• Thermally protected

This hi-fi stereo power amplifier is designed for mains fed applications. The circuit is designed for both symmetrical and asymmetrical power supply systems. An output power of 2 ´ 12 watts (THD = 0,5%) can be delivered into an 8 W load with a symmetrical power supply of ± 16 V.

The gain is fixed internally at 30 dB. Internal gain fixing gives low gain spread and very good balance between the
amplifiers (0,2 dB). A special feature of this device is a mute circuit which suppresses unwanted input signals during switching on and off.

Download the TDA1521/TDA1521Q Datasheet