Veroboard 12v Adjustable Power Supply




This circuit assumes that you have some knowledge of Electronics, if you have none, then I do not recommend you proceed. I take no responsibility for any injury or damage that this circuit may cause. The circuit that is shown did work for me and I had no problems with its operation. Use of the information presented here is subject to the terms of usage, which are shown at the bottom of this document. 

Circuit Description

This is an adjustable MOSFET Power Supply that uses as 12 volt Car / Motor Cycle Battery as a power source. It can be used for many things, Speed Controller, Light Dimmer, Foam Cutting Bow Power Supply, Glow Plug Driver. etc. I have used it for a Foam Cutting Bow Power Supply and a Glow Plug Driver, using a 12v Battery as a power supply. 

The general circuit uses a 555 Timer that is configured to turn the MOSFET on and off at a high speed. This in effect gives an increase/decrease in Voltage/Current across the load section of the circuit. When the Potentiometer is turned one way, the frequency of the MOSFET being turned on lessens, when turned the other way it increases the rate. 

You can use most general MOSFET’s in the circuit; I have used a BUZ71, BUK456 and BUK 457. I have matched the load of what I was using it for with the MOSFET. Most of the time I have not had to use a Heat Sink on the MOSFET’s, as the loads were low. However some uses may require a Heat Sink, please follow the MOSFET’s Manufacturers recommendations for the load you are using the circuit with. 

The circuit’s supply voltage is only limited by the components used. If you wish to use it for more than 12volt supply voltages, please ensure that you have components to suit the need. This may also require the addition of a power regulator to supply current to the 555 timer. 

If this does not scare you, then push on.. 

The schematic is shown below;


It has been built on a Veroboard of approx. 30mm x 30mm. The following is the layout for the board, showing the break points on the back of the board.


The component layout is shown below;


The Black lines on the Layout are jumpers made out of thin wire. (I used cut offs from Resistors). Also the angle that R1 is on, is only because the resistor I used was a 1 watt resistor, if can be ¼ Watt and the layout can be changed to make things all run in a straight line. It is your call, it won’t change the operation of the circuit.

Please make sure you fit the IC’s in the right way, check the Parts list for the connection points for all components.

The Parts required are;

Terms of Usage

This information can be used only for non-commercial purposes, it can only be used for commercial purposes with the written approval of the Author.  It can be freely distributed as long as reference is made to the author wherever it is displayed or used. The Author takes not responsibility for any inaccuracies in this document and also for any loss, damage or injury the information presented here may cause. If you have a all correction, contribution or suggestion that you wish to share with the Author, please send an email to replies will not be guaranteed.


Suggestions? Corrections? Remarks? e-mail - Craig Tarlington.
As I get quite a number of messages, it might take some time until you receive an answer and in some cases I get lost in the flood and you may even receive no answer at all. I apologize for this, and if you have not lost patience, you might want to send me a copy of your e-mail after a month or so.
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