Converter circuit 12Vdc to 24Vdc


This converter circuit shows a DC-DC converter that converting up 12Vdc source to a 24Vdc. 

It can be used to run radios, small lights, relays, horns and other 24V accessories from a 12V vehicle with a maximum draw of about 800mA.

This DC-DC Converter can be used to charge one 12V battery from another, or step up the voltage just enough to provide necessary overhead for a 12V linear regulator. 

Using one op-amp as a squarewave oscillator to ring an inductor and another op-amp in a feedback loop, it won't drift around under varying loads, providing a stable 24V source for many applications. 

With a wide adjustment in output this circuit has many uses.

Parts List:-

  • R1-R4,R7-R8 100K 1/4W Resistor
  • R5 470 Ohm 1/2W Resistor
  • R6 10K Linear Pot
  • C1 0.01uF Mylar Capacitor
  • C2 0.1uF Ceramic Disc Capacitor
  • C3 470uF 63V Electrolytic Capacitor
  • D1 1N4004 Rectifier Diode
  • D2 BY229-400 Fast Recovery Diode See Notes
  • Q1 BC337 NPN Power Transistor
  • U1 LM358 Dual Op Amp IC
  • L1 See Notes
  • MISC Board, Wire, Socket For U1, Case, Knob For R6, Heatsink for Q1

DC- DC Converter Notes:- 

  1. R6 sets the output voltage. This can be calculated by Vout = 12 x (R8/(R8+R7)) x (R6B/R6A).
  2. L1 is made by winding 60 turns of 0.63MM magnet wire on a toroidial core measuring 15MM (OD) by 8MM (ID) by 6MM (H).
  3. D2 can be any fast recovery diode rated at greater then 100V at 5A. It is very important that the diode be fast recovery and not a standard rectifier.
  4. Q1 will need a heatsink.
Source : Mr Aaron from


adelusi oluwatosin said...

Sir, Perhaps to buy a ready make inductor please sir kindly discribe which to buy. thanks for your assistant.

adelusi oluwatosin said...

Thank you sir for your helps, sir you made us to see LM358 as two in the schematic but you only mention one while given specimen. i want to perhaps UA and UB are thesa. Thanks.