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.
- 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:-
- R6 sets the output voltage. This can be calculated by Vout = 12 x (R8/(R8+R7)) x (R6B/R6A).
- 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).
- 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.
- Q1 will need a heatsink.
Source : Mr Aaron from http://www.aaroncake.net/CIRCUITS/12VDC_To_24VDC_Converter_Circuit.asp