12V To 24V DC-DC Converter Circuit

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This simple DC-DC converter can provide up to 24V from a 12V source. 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. It 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.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1, R2, R3, R4, R8, R7	6	100K 1/4W Resistor
R5	1	470 Ohm 1/2W Resistor
R6	1	10K Linear Pot
C1	1	0.01uF Mylar Capacitor
C2	1	0.1uF Ceramic Disc Capacitor
C3	1	470uF 63V Electrolytic Capacitor
D1	1	1N4004 Rectifier Diode
D2	1	BY229-400 Fast Recovery Diode	See Notes
Q1	1	BC337 NPN Power Transistor
U1	1	LM358 Dual Op Amp IC
L1	1	See Notes
MISC	1	Board, Wire, Socket For U1, Case, Knob For R6, Heatsink for Q1

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.

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Comments

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anonymous 12V To 24V DC-DC Converter Wednesday, January 04, 2012 5:00:15 AM

what is leg 9?

brij sahu jhansi india 12V To 24V DC-DC Converter Wednesday, December 07, 2011 4:08:57 AM

This is a great circuit .i used in my car to play computer woffers. {usb players} wich is operatied 24 volt dc . when i went a long drive i enjoy with woffers.

amit 12V To 24V DC-DC Converter Thursday, September 29, 2011 12:49:25 PM

hi every one... what is the efficiency of this circuit ?

snapter 12V To 24V DC-DC Converter Tuesday, September 27, 2011 1:54:35 AM

For D2, would it be OK if I change it to diode 1N4148?

collin 12V To 24V DC-DC Converter Monday, May 09, 2011 3:03:30 AM

This is a great circuit, but if you want a really easy boost converter, just go buy a pwm chip (they make ones for this exact purpose).

anonymousAlex 12V To 24V DC-DC Converter Friday, February 18, 2011 11:17:39 PM

Hello everyone I love this circuit but I want to find out if I add more power transistors to this circuit if it can handle higher currents. Please send coments to my email thanks

Josip 12V To 24V DC-DC Converter Thursday, January 06, 2011 11:53:32 AM

Hello everyone, we finally got this circuit working. For Q1, we had to replace BC337 with BC331 because BC337 wasn't strong enough and kept getting fried. BC331, however, requires a heatsink as well, so don't forget that. Also, as L1 we used a serial connection of 1.7 mH and 0.2 mH inductors. The L1 mystery has been solved at last. :) Cheers.

Hinkus Pooper 12V To 24V DC-DC Converter Sunday, December 05, 2010 11:14:21 PM

Can I get 43Kw from this circuit or will I need a heatshink ?
(Editor's notes: Uh, no.)

Josip 12V To 24V DC-DC Converter Sunday, November 07, 2010 6:19:04 PM

Can author of this circuit please post inductance of L1 since there is no info about permeability of toroidal core?

Josip 12V To 24V DC-DC Converter Thursday, November 04, 2010 7:12:43 PM

Please give us more information about L1 because it's hard to calculate exact inductance without info such as permeability. Best option would be to give us exactly how many henries there should be. Thanks.

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anonymous	12V To 24V DC-DC Converter	Wednesday, January 04, 2012 5:00:15 AM
what is leg 9?
brij sahu jhansi india	12V To 24V DC-DC Converter	Wednesday, December 07, 2011 4:08:57 AM
This is a great circuit .i used in my car to play computer woffers. {usb players} wich is operatied 24 volt dc . when i went a long drive i enjoy with woffers.
amit	12V To 24V DC-DC Converter	Thursday, September 29, 2011 12:49:25 PM
hi every one... what is the efficiency of this circuit ?
snapter	12V To 24V DC-DC Converter	Tuesday, September 27, 2011 1:54:35 AM
For D2, would it be OK if I change it to diode 1N4148?
collin	12V To 24V DC-DC Converter	Monday, May 09, 2011 3:03:30 AM
This is a great circuit, but if you want a really easy boost converter, just go buy a pwm chip (they make ones for this exact purpose).
anonymousAlex	12V To 24V DC-DC Converter	Friday, February 18, 2011 11:17:39 PM
Hello everyone I love this circuit but I want to find out if I add more power transistors to this circuit if it can handle higher currents. Please send coments to my email thanks
Josip	12V To 24V DC-DC Converter	Thursday, January 06, 2011 11:53:32 AM
Hello everyone, we finally got this circuit working. For Q1, we had to replace BC337 with BC331 because BC337 wasn't strong enough and kept getting fried. BC331, however, requires a heatsink as well, so don't forget that. Also, as L1 we used a serial connection of 1.7 mH and 0.2 mH inductors. The L1 mystery has been solved at last. :) Cheers.
Hinkus Pooper	12V To 24V DC-DC Converter	Sunday, December 05, 2010 11:14:21 PM
Can I get 43Kw from this circuit or will I need a heatshink ? (Editor's notes: Uh, no.)
Josip	12V To 24V DC-DC Converter	Sunday, November 07, 2010 6:19:04 PM
Can author of this circuit please post inductance of L1 since there is no info about permeability of toroidal core?
Josip	12V To 24V DC-DC Converter	Thursday, November 04, 2010 7:12:43 PM
Please give us more information about L1 because it's hard to calculate exact inductance without info such as permeability. Best option would be to give us exactly how many henries there should be. Thanks.