Simple 6V to 12V boost converter circuit using BD679 transistors

In this post I am going to show you the 6v to 12v boost converter circuit. Imagine you have 6V battery. But you need to use 12V of load like LEDs.  How do? See in your store, has only transistor and simple parts without IC.

Stop thinking to buy new one 6V battery.

You may can use these components to easy to solve the problems.

Some called 6 volts DC to 12 volts DC step up converter circuit. But the output is low current.

How it works

Look at the circuit Diagram below.

Simple 6V to 12V boost converter circuit using BD679 transistors

Here is the step-by-step process.

This circuit includes Q1, Q2, R1, R2, R3, R4, R5, D1, C1 and C2. They are the astable multi vibrator mode. And the output is Square Wave in many frequencies of positive pulse signal.

Then, look at R6 limits current flowing come to base of Q3 and collector of Q4.

In this condition, Q3 get a bias current, it runs. In concrast, Q4 does not get a bias current, so it does not run.

While Q3 runs. The current can flow through L1, D2 to a output. And some current via ZD1, cause drop voltage at ZD1.


Which be output voltage and voltage this increase continually poverty voltage that equal to 12 the volt.

By have R7 be limit current already change come in the way pin B of Q4

make Q4 work be make Q3 stop bias.

Then make output voltage be 0 volt, but when positive pulse signal that made come to then change come to at R6 then make Q3 bias again.

And work character as before but there are many speeds then can make output that appear

can come out 12 volt all the time by have C3 perform in something current filter smoothly

before increasingly lead output voltage go to be usable.

Parts you will need

0.25W Resistors, tolerance: 5%
R1, R4: 1.8K
R2, R3: 4.7K
R5: 1K
R6: 1.5K
R7: 33K
R8: 10K
C1, C2: 0.1uF 50V Ceramic or Mylar
C3: 470uF 25V Electrolytic
D1, D2: 1N4148
ZD1: 12V 0.5W Zener Diode
Q1,Q2, Q4: BC547, 0.4A 40V Transistors
Q3: BD679 NPN transistor
L1: 100uH-22ouH

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Sir what value is L1?

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