Do you have too many broken appliances? You need this electronic waste recycling. You can take them to be 9v regulated power supply circuit. We will show you in 3 circuit ideas.
All the circuit never use ICs. We can use the many replacement devices. Even you can adjust the other voltage and current rate as you want.
Each circuit has a first section of the unregulated power supply circuit. So we should see it first. It will convert AC-main to DCV of about 17V to 18V,
In circuit has 3 main components.
The transformer—Converts AC-main(high voltage) to low ACV about 12V.
Then, the bridge rectifier—Rectified from AC (Alternating Current) to DC (Direct Current).
Last, the filter capacitor—Smooth the pulsating voltage from a power supply into a steady direct current (DC).
Adding more capacitors in parallel with C1 for more capacitance. To get DC voltage as it should be and low ripple.
If you want the max output current, you need to use enough current of a transformer and diodes.
Next…meet the circuit!
First—Simple 9V positive voltage regulator using Zener diode and transistor
If you are looking for 9V 1A regulator circuit. First, you will use IC-7809. It is easy and cheap. But now, we will come back to use the old circuit but still useful.
In the circuit above shows a simple series voltage regulator using a transistor and Zener diode.
Keep reading: Small Zener diode voltage regulator circuit with PCB
This circuit has a low pass filter. Which it is a special circuit that includes C1, R1, and C2. They help us to remove AC ripple. The voltage across C2 is a very stable voltage source.
The Zener diode-ZD1 provides the reference voltage. It has a value of 10V 0.5W.
ZD1 keeps the voltage constant across the base of Q1.
Q1 is a power transistor, gives the high current to load. The output at the collector of Q1 has a voltage across the load of 9V. Because of some voltage drops in BE of Q1.
R4 is a safety resistor for Q1. It acts like a fuse that protects Q1 when too many currents.
We can use the many NPN transistors like 2SC1061, 2SD313, TIP41, MJE3055, and more.
Second—Simple 9V fixed and Variable voltage(6 to 12V) DC Power supply using TIP31 transistors
This is a simple DC regulated power supply circuit. The output voltage gives the fixed and variable voltage from 6V to 12V. We can set it is 9V with adjusting of potentiometer-VR1.
The max current is 1A. We should choose a power Transistor-Q1 is TIP41, or other NPN power transistors such as TIP31, MJE3055, 2SC1061, etc.
But They must hold with enough heat sink. While it is working it is too hot.
If you cannot use BC182. You can use other NPN transistors like BC548, 2SC1815, 2N3904, and more instead.
Update: I did read the advice of Colin Mitchell, the weakness of this circuit. I changed the new circuit, removing ZD1 and R3, making the circuit easier. And you can still adjust the regulated voltage of the output.
If you want to learn how it works more. Read: DC voltage Regulator
Third—9V Regulator low current Supply
This is another 9v regulated power supply circuit. It uses 2N3055 as the main, so high current up to 2A. If we use 2A to 3A transformer and C1 capacitance is 2200uF.
Its pattern is quite similar to the above circuit. But it is different at the placement of some parts.
Each circuit, the power transistor requires enough heat sink because while it works it is too hot.
Read more >> How Op-amp Regulator circuit works
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