REGULATED POWER SUPPLY USING 741 AND 2N3055

DC regulated power supply using 741 op amp ic and 2n3055 power transistor


DC Regulated power supply Using 741 Op Amp IC And 2N3055 Power Transistor

The voltage regulated power supply provides an adjustable voltage output at a load current up to 1A. The supply has a built-in overload protection.

regulated power supply circuit using 741 op amp  ic and 2n3055 transistor

PARTS LIST
R1 6.8kΩ
R2 1kΩ
R3 10kΩ  Potentiometer
R4 22kΩ
R5 10kΩ
R6 0.6Ω 1W
R7 330Ω
R8 2.2kΩ 1W
C1 2200µF 50v
C2 100µF 50v
C3 22µF 16v
C4 o.1µF 50V
D1 3 Amp Diode
D2 3 Amp Diode
D3 1 Amp Diode
D4 6.8V 500mA Zener Diode
D5 6.8V 500mA Zener Diode
T1 2N1481 or D313 or 2SC1061
T2 2N3055
T3 BC107
IC1 LM741
TR1 SEC 15V, 2AMP

Rectifier diodes D1 and D2 along with capacitor C1 provide the main unregulated supply. D3, C2, R8 and zener diode provide a negative voltage supply for the 741. The non-inverting input terminal of 741 is given a stable voltage by R3 which is the control to set the output. A fraction of the regulated output is fed back via R4 and R5 to the inverting input terminal. The operational amplifier adjusts its output voltage so as to keep the voltage at the input terminals equal. Thus the output gets regulated. The output of 741 is amplified by a compound emitter follower T1 and T2.

All the current flows through R6. If the load current exceeds 1A, the voltage drop across R6 exceeds 0.6 volts and T3 starts conducting. This bypasses the supply to T1 and T2 and the regulating action stops. The output voltage therefore starts falling when the load current exceeds 1A. Any of the output terminals can be grounded to get a positive or a negative voltage with respect to the ground.


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12 comments on “REGULATED POWER SUPPLY USING 741 AND 2N3055
  1. Sue says:

    Hi… really love this design doing something similar, except I need a regulated voltage of 0 – 5V and 200mA current, what resistances do I change to make that happen?

  2. Netcruiser says:

    For 5A output pwer you can use BD249

  3. ddi.1970 says:

    but 5A can I use two 2n3055?

  4. ddi.1970 says:

    for 5A use 2 2n3055?

  5. Appreciate this article, It was an incredible read that was very helpful.

  6. Samuel Haren says:

    excellent information.

  7. Amiable post and this fill someone in on helped me alot in my college assignement. Thank you for your information.

  8. seetharaman says:

    Hi please add 100 ohms 1/4w resistance in the base circuit of current limitting trasistor T3, to protect it during an out put dead short, to limit the Ibe to safe limit. without which the be junction of the transistor will blow, otherwise a nice circuit keep it up.

  9. NelsonTrebor says:

    R1,R2,R4,R5,R7 what wattage do we use? 1W,1/2W or 1/4W. Sorry for my noobness..i just want to make this Power Supply for my Electronics project.

    and btw, what fuse do we use for this?

    Replay ASAP.

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