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# 12V battery to 5V 1500mA DC converter regulator

If we need to use 12V to 5V voltage regulator. This is the 5V 1500mA DC regulator circuit. Which is a simple circuit using IC-7805 to the fixed regulator 5 volts and TIP41-NPN power transistor to increase current up to 2A.

Example experiment
I use the 7805 power supply with the 12V battery. To reduce the constant voltage of 5 volts.
I try to use the load is 4.7 ohms 5W resistors. As principles, it will use the current about 5V/4.7ohms = 1A. I measure the current of about 0.7A and the voltage drop is 4.9V, but it is still usable. As Figure 1

Figure 1 Testing pure IC-7805 not over 1A current.

But sometimes we want a higher current. For example, I like to use a current of 1.5A. It requires a transistor to increase the output current up.

We’ve recommended this feature circuit is 12V to 5V 3A DC converter step down Regulator. But someone said the PNP transistor is not popular. They want to use an NPN type.

Today I recommended this simple circuit.

I use the TIP41 transistor. In principle, it can supply the current about 2A, which it is enough to use. I like this number. Because it is cheap, efficient, and reasonable.

As Figure 2 is the circuit diagram.  Then, I test circuit with about the load, 2.4 ohms resistor.  measure current approximately 1.3A, and voltage drop is 4.9V.  It can be used as we want. As Figure 3

Figure 2 The circuit diagram

Figure 3 Testing with high current load.

### ‘Keep reading: Four Small 5-volts DC Regulator Circuits »

I put a Diode-1N4007 voltage to offset the loss of the transistor between pin BE.

We insert LED1 to indicated power on of this circuit and a series resistor-R1 is used to limits current to a safe value.

C1, C3 is filtered capacitors to smooth dc current input and output sequence.
C2, C4 is noise filter spark current.

While Q1 is working it will very hot so we must mount it with a large heatsink.

Component list of 12v to 5v voltage regulator
IC1___LM7805___5V dc regulator IC
Q1___ TIP41____2A 50V NPN power transistor
C1____1000uF 35V___Electrolytic Capacitor
C3____100uF 25V_______”________”____
C2____0.1uF 50V___Ceramic or mylar capacitors
C4____0.01uF 50V____”____________”_______
D1____1N4007______1A 1000V Diode
LED1____LED any color as you like
R1____820 ohms 0.25W

Heatsink, wires and more etc.

### This Post Has 8 Comments

1. As an added bonus if you thermally couple the transistor to the regulator (close together on the same heatsink with thermal grease and mica insulator) the transistor will be protected from overheating. If the transistor overheats it also heats up the regulator, and the regulator has built in thermal regulation. When the regulator shuts down, it also shuts down the transistor.

2. can i parallel the transistor so it gives much current output?

3. Hi everyone,

I implemented this Circuit on a breadboad with the aim of using it to charge my android phone via two input sources. With
(1)Three small DIY Solar Panels that i connected in series and it gave about 13V-10V

(2)Six 18650 Li-on cells that i harvested from my old laptop battery,i also conected them in series and parallel to give out about 12V-10V

Now my problem is that…each time i connect the usb head to my phone,it gives out the 5V BUT THE CURRENT drops rapidly from 870mA to 0mA…instead of increasing gradually from 870mA to 1000mA as my normal Phone charger does,please what could be the cause and how can i make it retain current to charge my android phone the same way its normal charger does?

PS: It’s not only with this circuit that I’ve observed this,I tried with several other Linear Voltage Regulators like the LM317T and still get the usual 5V but the current drops rapidly from 870mA to OmA. Please i need an urgent reply ([email protected]). Thanks in advance

4. Sir i try this circuit I tested on 12 volt 8 amp batter but at the out side current show 10.56 instead of 5 volts. Sir can u tell me how to reduce current at least 5 volt. Amp are on my demand but current is very high. Please help me.

5. Why is the current limited to 2amps. The tip41 transistor is capable of 6amps per spec?

6. why is it that i get a much higher voltage output is there something wrong i get 14v on the output

7. This circuit output is 5v/300mA only.

8. led products

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