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Glow plug driver

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Steve G11/07/2020 20:56:31
24 forum posts
8 photos


I have just completed a build of a flat 4 cylinder 4 stoke engine that uses glow plugs. I did think about using spark plugs but I thought that glow plugs would aid simplicity.

However, trying to find a circuit diagram online for a 4 x glow plug driver is proving fruitless. Does anyone have any idea where I could find such a diagram? I have looked at the option of buying a 4 x glow plug driver, but funds are limited and they are expensive devices.

I have found a single glow plug driver diagram online and perhaps modifying it to drive 4 plugs, but not sure if it would have sufficient current to drive 4 x mosfets.

I may have to revert to using 4 single cell batteries attached individually if all else fails.

Any ideas would be gratfully received.



John Pace11/07/2020 21:44:48
191 forum posts
180 photos

Contained withing this thread from 2012 by Phil W
"Pneumatic brake for CNC rotary table"
will lead you to his site here which
has a circuit for a 9 cylinder version of
what you need .

Don't Know if this will be of any use to you but may be of some use

in a modified form.


Steve G11/07/2020 21:49:45
24 forum posts
8 photos

Thanks John,

Just looked at the link. I will look into that one. I will have to practice my arduino programming skills.

Thanks again.


Bazyle11/07/2020 22:48:34
5296 forum posts
201 photos

Just make a lead acid battery.........

Most car batteries fail because one cell alone has died so a bit of examination and a drill finds the inter-cell connections to use one of the cells on its own.

JasonB12/07/2020 07:19:43
18329 forum posts
2024 photos
1 articles

Does not need a fancy circuit, just connect all the electrodes together and to your supplies +ve and take the negative to the head or crankcase.

Take a look at Dean's V12, just a brass bar connecting all the plug electrodes on each bank.

Robert Atkinson 212/07/2020 11:17:47
705 forum posts
16 photos


You only need fancy drive circuitry if it's a flight engine where weight and endurance are important.

Phils radial engine circuit has issues, particuarly the 0.47uF capacitor across the gates of the MOSFETs. This stresses the mocrocontroller outputs and keeps the MOSFETs in their linear region longer increaing heating and battery consumption. Fo a simple sequential switch a couter decoder like a CD/HEF 4017 or 4022 would be easier to use.

For a flat four I'd run the plugs series / parallel. Put a link / busbar between the two plugs on each side then connect the battery (or other source), with a voltage twice the rating of each plugs, between the two links. The crankcase will be at half battery voltage but as long as the battery is isolated tthat is not an issue.

For bench running a transfomer can be used, glow plugs don't mind if power is AC or DC.

Robert G8RPI.

Edited By Robert Atkinson 2 on 12/07/2020 11:34:34

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