Power amplifier electronic circuits-tube audio rf amplifiers

Electronic Amplifier Circuits-Power amplifier, audio amplifier designs and circuits

May 24th, 2010

Power Supply Circuit Using LM 317 IC

Circuit Description

The circuit diagram 40V 2A power supply circuit has been described here. The central part of this circuit is the voltage regulator IC LM 317. This power supply circuit is ideal for circuits such as power amplifier circuit can deliver a current of 2A. In this circuit the transistor Q1 acts as pass transistor for increasing current capability. The output voltage is set to 40V by using resistors R5 and R8.

Parts List

Resistors: R1 (39 ohm 1 or 2W Resistor), R2 (22 ohm 1/4W Resistor), R3 (68K 1/4W Resistor), R4 (220R 1/4W Resistor), R5 (47K 1/2W Resistor).

Capacitors: C1 (3300µF 50V Electrolytic Capacitor), C2, C5 (100nF 63V Polyester Capacitors), C3 (10µF 63V Electrolytic Capacitor), C4 (220µF 50V Electrolytic Capacitor).

Active Components: D1 (Diode bridge 4A), D2 (1N4002 Diode), D3 (LED any color), U1 (LM317), Q1 (TIP42A Transistor), T1 (230V Primary, 40V 2A, Secondary, mains transformer).

Circuit Diagram

Power Supply Circuit Using LM 317 IC

Power Supply Circuit Using LM 317 IC


  • Use a good quality PCB to assemble this circuit.
  • Use four 1N 4007 Diodes if Diode Bridge is not available.
  • If you want any other out put voltage use a 10 K pot instead of R5 and adjust it.

May 7th, 2010

Dual Adjustable Power Supply Circuit

Circuit Description

The circuit diagram of Dual adjustable power supply has been given here. This circuit is based on two ICs namely LM 317 and LM 337. Among these ICs, LM 337 is the negative complement of LM317. These ICs work at voltage range between 1.2 V and 30V and are capable of delivering 1.5A current. One of the most advanced features of these ICs is the short circuit protection.

This circuit gives an output dual DC voltage in the range of -15V to +15V. Filtering and ripple rejection in this circuit is accomplished by the series of capacitors from C1 to C8. The job of controlling the output is done by resistors R1, R2, R3 and R4 (R1 and R2 for LM 317 and R3 and R4 for LM 337).

Parts List


C1, C2 (2200 uF 50V)
C3, C4, C5, C7 (2.2 uF 50V)
C6, C8 (100 uF 50V)

R1, R4 (5K Potentiometer)
R2, R3 (220 Ohms 1/4 W Resistor)

Active Components:
D1 to D4 IN 4007 Diodes
U1 LM317 U2 LM337

T1 (24 0 24 Center Tapped 2 Ampere Transformer)
S1 (SPST 2 Ampere Switch)

Circuit Diagram

Dual Adjustable Power Supply Circuit
Dual Adjustable Power Supply Circuit


  • This circuit is a must on an electronic hobbyist’s workbench.
  • The transformer should be produce a min of 3 A with (24 0 24) output voltage.
  • Resistors R1 and R4 can be turned to vary the positive and negative voltages.

Adequate heat sinks should be provided for ICs.