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Ignition coil driver

ped

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Hi guys.
I have some IRF640's kicking round and since there are people here with a lot more experience than me, I thought I'd ask here.

I want to make a "simple as can be" mosfet driver for old car ignition coils, using as few a components as possible, preferably with a perf board scheme or layout as I'm hopless at doing them!.
I know a few guys on here might have such a circuit kicking round. I've found a few on the net using 555's but couldn't get them going.

Going to be running it at 12-24vdc.

Thanks

Ped
 
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paul1598419

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All the drivers I've seen using ignition coils were for HeNe laser tubes. I'm unaware of any other uses for these type drivers. I do have a schematic kicking around here for a HeNe driver, but that is the total of what I've got. Never heard of driving one with NE555s.
 

Anthony P

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It's been awhile since I did this kind of project... decades!
If you are using the 555 with IRF640 circuit that is common on the internet, it really really should work for you. I would bet it is just a simple wiring error, or a bad component. If you want to Frankenstein it, the only component you need is a relay configured to turn itself off and on. In fact, this is how commercial oudin coils (BD10, BD50) work to this day.
 

ped

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@Anthony oh I'm under no illusion it's something I'm doing wrong, I know it is...I'm just hopeless at perf / stip board designing.
I think it's an age thing, translating a schematic into reality using perf / strip board just taxes my brain nowadays :/

Ped
 

Anthony P

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@Anthony oh I'm under no illusion it's something I'm doing wrong, I know it is...I'm just hopeless at perf / stip board designing.
I think it's an age thing, translating a schematic into reality using perf / strip board just taxes my brain nowadays :/

Ped
Ever try bread board? I had not until a few years ago... now I am hooked.
 

absolute

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Ever try bread board? I had not until a few years ago... now I am hooked.
Careful with what you test on breadboard, a driver like this can potentially draw lots of current and melt its small contacts.
 

Anthony P

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Careful with what you test on breadboard, a driver like this can potentially draw lots of current and melt its small contacts.
Thanks for the tip. I suppose PED could keep the high current part of the circuit off the BB, but still verify the 555 on board.
 
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Seoul_lasers

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Hi guys.
I have some IRF640's kicking round and since there are people here with a lot more experience than me, I thought I'd ask here.

I want to make a "simple as can be" mosfet driver for old car ignition coils, using as few a components as possible, preferably with a perf board scheme or layout as I'm hopless at doing them!.
I know a few guys on here might have such a circuit kicking round. I've found a few on the net using 555's but couldn't get them going.

Going to be running it at 12-24vdc.

Thanks

Ped
Best to look at building a ZVS driver which is as simple as it can get. The 555 timer idea is nice, but won't allow for much current.
the IRF640 can supplement the IFRP250 shown here in the diagram. Get the ferrite choke from an old PSU, and a decent sized capacitor and you're good to go.

Do be aware that the HV power supply using a ZVS driver is capable of outputting some serious current.
Large ZVS PSUs can do well over 2KW.

1570694875802.png

basic diagram
1570694383792.png
 

ped

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Thank's SL, but the ignition coil won't allow for a center tap.

Ped
 

Seoul_lasers

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There is a way of doing a 2 wire config with a ZVS driver.
This is referred to as a isolated input configuration and uses an isolation transformer that is built off a
ferrite transformer core. you really don't need many turns. link below.

***I have done this before. I can tell you that this setup will indeed work for ignition coils.
Do be careful with your power input. Easy to get 80KV with not much effort.


 
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ped

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@SL Thank's. I'll check that out.
@Alaskan. Thank's, the Arduino idea is good one, I have one of them as well. The other circuit is the one I transferred (unsuccessfully) to vero board and I couldn't get it going.
Unfortunately I have a very short attention span and if it doesn't work first time, I bin it :D.

Ped
 

WizardG

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You can do a ZVS driver W/O a center tap this way: https://www.backyardscient.ist/induction-heater
but using this circuit to drive an ignition coil could be problematic. These ZVS circuits drive the load at the resonant frequency determined by the tank capacitor and the inductance of the 'load' coil. This tends to be in the range of several tens of kHz to a couple hundred kHz which would likely be far too high for an iron core ignition coil. That being said, if you could find the natural resonance frequency of the secondary winding of the ignition coil you plan to use and drive at that frequency the voltage output would be......impressive. Not quite DRSSTC levels of arcage but probably better than the majority of flybacks. There are some ferrite core ignition coils out there used in high energy and MSD type ignition systems and those should be a good fit for a ZVS driver.
 
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Seoul_lasers

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You can do a ZVS driver W/O a center tap this way: https://www.backyardscient.ist/induction-heater
but using this circuit to drive an ignition coil could be problematic. These ZVS circuits drive the load at the resonant frequency determined by the tank capacitor and the inductance of the 'load' coil. This tends to be in the range of several tens of kHz to a couple hundred kHz which would likely be far too high for an iron core ignition coil. That being said, if you could find the natural resonance frequency of the secondary winding of the ignition coil you plan to use and drive at that frequency the voltage output would be......impressive. Not quite DRSSTC levels of arcage but probably better than the majority of flybacks. There are some ferrite core ignition coils out there used in high energy and MSD type ignition systems and those should be a good fit for a ZVS driver.
not entirely true.... ZVS drivers are used all the time on ignition coils without issue! In fact a modified version of the ZVS driver is used on commercial electronic SSICs.






 
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WizardG

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Interesting video but, the narrator says he's getting 10-12 kV which is just a fraction of the output capability of the coil. And the commercial ignition circuits using some version of a ZVS use ferrite core coils. You can also hear the core of the driving transformer he's using screaming it's protest at all the stray inductance in the circuit.

I tried a few experiments as a teenager (ghod that was a long time ago!) with an ignition coil I 'decanned'. I removed the original iron core and replaced it with a ferrite antenna rod and got some pretty decent results but discovered quickly that the duty cycle of that type of coil, used at a frequency far above what it was designed for, is tragically short.

A Mazzili type ZVS circuit driving an iron core automotive coil at the resonant frequency of its secondary (~3kHz IIRC) would be loud as sin but I think you'd be able to pull at least two inch arcs. YMMV
 

Seoul_lasers

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True, but he's only inputting around 10V after that isolation transformer. I have a video of around 24V and the ignition coil is doing closer to 60KV. One can also change the capacitor to be inline with the resonant frequency of the given transformer. I have also used these drivers on modified MOTs. Granted you do need a big ZVS driver and tank cap to drive them.

Not disagreeing with you about the resonant frequency.
 




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