In this post, I am going to show two Negative Voltage Regulator circuit ideas. 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
Simplified schematic diagram of 12.6V Negative Voltage Regulator using PNP Emitter Follower
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 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
9V negative power supply circuit, low ripple
This is a simple 9V negative power supply circuit that low ripple unregulated circuit. It has an output current of about 1A max. Often we make many positive voltage supplies. But we sometimes need to make negative power circuit. See in the circuit below.
But it is special, low ripple, low noise, and a constant voltage at 9V.
While unregulated circuit has too much a load current. It also has too much ripple or a noise.
In general, We will reduce the ripple by adding the large capacitor. It is a nice way.
Also a good idea, we use the gyrator effect.
The input capacitor C2 at the base of a transistor. It makes a stable voltage for the current gain of the transistor.
If transistor has a lot of gains such a 50 it can reduce a rate of ripple to low down.
The transistor will increase a high current to the output at its emitter.
The circuit is interesting because it is a smaller, cheap. We can this circuit is a high quality smoothed supply for a lot of loads, DC motor, Coils, Power lamps and more.
The output is full at 1A. Because of:
- a transformer is 1A to 2A, 6.3V SEC.
- And C1-1000uF 25V Electrolytic capacitor, you can change with 2200uF 25V, or add another one in parallel.
While the transistor is working, will have too hot. We should mount the big size heatsink. And add a fuse to protect the circuit from overload current.
But you want to builds easily circuit, you may use IC-7909 DC regulators
- Simple Zener diode voltage regulator circuits
- 9V regulated power supply circuit using transistors and zener
- Basic DC voltage Regulated 13V low current
This circuit requires enough power supply. Do you have this one? If you do not have it. Look:Learn Many Power supply circuits
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