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12.6V Negative Voltage Regulator using PNP Emitter Follower

Today we come to see a Negative Voltage Regulator circuit. Before we use the just positive regulator as Simple DC regulator using transistor and Zener. The output voltage of this circuit is 12.6V.

We use PNP Transistor be main electronic parts. By it is used as the character of emitter follower or voltage follower, make have a high current of about 0.7 Amp.

The working Principle
12.6V Negative Voltage Regulator using PNP Emitter Follower


Simplified schematic diagram of 12.6V Negative Voltage Regulator using PNP Emitter Follower

To begin with, the 220VAC or 110VAC(in the US) is fed to the power cord. It flows through the step -down transformer-T1 via S1(ON-OFF)switch and F1 (500mA fuse).

Then, we have about 12VAC output from the T1-transformer is fed to the D1-D2, full wave rectifier. Now, both diodes rectified the AC-Alternating Current to DC-direct current.

Next, the pulsating DC  is filtered by C1-1,000uF capacitor.

And then, the electric current flow to a filtering regulator circuit. They include R1, ZD1, ZD2, R2, and Q1. Next, the R1-resistor will limit current to both ZD1, ZD2-Zener diode. Then, The Zener diodes are used as a specific reverse breakdown voltage across them is 12V(constant voltage).

Next, this low current flow base Q1 to increase current up, now ready to load.

The part that performs as fix voltage. The output is ZD1 and ZD2, from the circuit notes 6V

The capacitor C2-2200uF help give the circuit to the stability increasingly.
For other detail see in a picture.

Parts will you need

Q1 : TIP42 or equivalent (100V 6A, PNP transistor), Quantity: 1
ZD1, ZD2: 6V,0.5 watts Zener Diode, Quantity: 2
D1-D2 : 1N4007, 1A 1000V Silicone Diode, Quantity: 2
C1: 1,000uF 35V, Electrolytic Capacitors, Quantity: 1
C2: 2,200uF 35V, Electrolytic Capacitors, Quantity: 1
R1: 220 ohms 1/2W Resistors tolerance: 5%, Quantity: 1
R2: 1K 1/4W Resistors tolerance: 5%, Quantity: 1
F1: 0.5A Fuse, Quantity:1
S1: ON-OFF Switch(SPST Switch), Quantity:1
T1: 0.5A, 12V Center Tap Transformer

Related Negative Voltage Regulator

  1. Simple Zener diode voltage regulator circuits
  2. 9V regulated power supply circuit using transistors and zener
  3. Basic DC voltage Regulated 13V low current

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