Need Help with off the line Ignition coil driver.

[imix500]

That looks right. It did work, but I went with a square wave generator driving a triac.

 

[unclejed613]

actually, more like this..... this gives a better ground reference for the secondary
the parts can be any mosfet with a high current rating and the diode can be any 3 amp or higher type, preferably a fast recovery type.

 

[chingyg]

Here is an actual Line voltage driven CD type ignition coild driver circuit.
This circuit is very adaptible and forgiving.

Nice design. What exactly is X2? and why is everything suppose to be 4X peak voltage. that is 300X4=1200V, things at that type of rating is quite expensive. Will 600V be fine? and what exactly does 2 coil connected in series mean? - or coil A to + of coil B? can I use full wave rectification and a smoothing Cap on it? or maybe 2 coil in anti parallel.

 

[tcmtech]

Sorry I did not label X2 its a diac or it can be a better quaity MOV with a good breakover voltage.
It can also be 1 or more mini noen glow bulbs in series. They have an additive breakover voltage,
Basicaly its just any device that will go from nonconducting to conducting at a specific voltage.
Two coils in reverse series is where you put the power in the + of one then connect - to - and take the power out the + on the second one.
Being the two coils are being driven 180 degrees out of phase from each other you get a much higher voltage differerntial at the HV outputs.

I built this circuit some time ago for a college science show day at the local college physics center.
I used two 6 volt ignition coils set up and driven this way. I placed them in an ice cream pail full of oil and called it "Bucket of Volts".
All you saw was a sealed plastic ice cream pail with two solid copper leads sticking through the lid. when you pressed a button on the drive box it would shoot 6 inch sparks between the two leads.
Scarred the crap out of the kids but they still kept pushing the button!

Being this is a highly inductive circuit you need the high voltage ratings to get any decent life out of it.
600 volt should work but it could still go give you problems when you draw the high voltage arcs out to a long lengh. Try it and find out!
A 1200v Scr is only a few dollars at digikey or any other online electronics parts supplier. Same with High voltage capacitors and diodes. If you know where to look this is a under $25 circuit to build. $50 if you need to buy the coils new.
But any ignition coil will work with this circuit. Even ones off lawn mowers!

 

[chingyg]

Sorry I did not label X2 its a diac or it can be a better quaity MOV with a good breakover voltage.
It can also be 1 or more mini noen glow bulbs in series. They have an additive breakover voltage,
Basicaly its just any device that will go from nonconducting to conducting at a specific voltage.
Two coils in reverse series is where you put the power in the + of one then connect - to - and take the power out the + on the second one.
Being the two coils are being driven 180 degrees out of phase from each other you get a much higher voltage differerntial at the HV outputs.

I built this circuit some time ago for a college science show day at the local college physics center.
I used two 6 volt ignition coils set up and driven this way. I placed them in an ice cream pail full of oil and called it "Bucket of Volts".
All you saw was a sealed plastic ice cream pail with two solid copper leads sticking through the lid. when you pressed a button on the drive box it would shoot 6 inch sparks between the two leads.
Scarred the crap out of the kids but they still kept pushing the button!

Being this is a highly inductive circuit you need the high voltage ratings to get any decent life out of it.
600 volt should work but it could still go give you problems when you draw the high voltage arcs out to a long lengh. Try it and find out!
A 1200v Scr is only a few dollars at digikey or any other online electronics parts supplier. Same with High voltage capacitors and diodes. If you know where to look this is a under $25 circuit to build. $50 if you need to buy the coils new.
But any ignition coil will work with this circuit. Even ones off lawn mowers!

Questions:
for X2, I know that MOV, and neon bulb would work but for DIAC? its DIAC suppose to be like breakdown at a specific voltage?
and I can't buy stuff online, don't have a credit card, all the rest of money is locked up in a fixed deposit. well $50 is like 450ZAR, and guess how much I have right now, 20ZAR. Haha. but I am selling explosives, bombs and stun guns to fund my research, lucky I am not in America, the FBI wont be coming through my roof in the next 5 minute after they've read this post. Haha

 

[chingyg]

Sorry I did not label X2 its a diac or it can be a better quaity MOV with a good breakover voltage.
It can also be 1 or more mini noen glow bulbs in series. They have an additive breakover voltage,
Basicaly its just any device that will go from nonconducting to conducting at a specific voltage.
Two coils in reverse series is where you put the power in the + of one then connect - to - and take the power out the + on the second one.
Being the two coils are being driven 180 degrees out of phase from each other you get a much higher voltage differerntial at the HV outputs.

I built this circuit some time ago for a college science show day at the local college physics center.
I used two 6 volt ignition coils set up and driven this way. I placed them in an ice cream pail full of oil and called it "Bucket of Volts".
All you saw was a sealed plastic ice cream pail with two solid copper leads sticking through the lid. when you pressed a button on the drive box it would shoot 6 inch sparks between the two leads.
Scarred the crap out of the kids but they still kept pushing the button!

Being this is a highly inductive circuit you need the high voltage ratings to get any decent life out of it.
600 volt should work but it could still go give you problems when you draw the high voltage arcs out to a long lengh. Try it and find out!
A 1200v Scr is only a few dollars at digikey or any other online electronics parts supplier. Same with High voltage capacitors and diodes. If you know where to look this is a under $25 circuit to build. $50 if you need to buy the coils new.
But any ignition coil will work with this circuit. Even ones off lawn mowers!

Do I have to use half wave rectification, what about a bridge rectifier and a smoothing capacitor of about 220uF?

 

[tcmtech]

It does not need to be half wave. I just went for simplest example.

Full wave will work just fine but dont use the smoothing capacitor. The incoming wave dropping to zero volts every half cycle is a back up reset for the SCR if it were to latch and not get reset by the coil inductance.

 

[unclejed613]

or you can do a "roll your own" diac.... like so..... just use complementary transistors

 

[chingyg]

It does not need to be half wave. I just went for simplest example.

Full wave will work just fine but dont use the smoothing capacitor. The incoming wave dropping to zero volts every half cycle is a back up reset for the SCR if it were to latch and not get reset by the coil inductance.

What about an anti parallel diode across the SCR, will that help? or jeopardize the SCR from switching off?

 

[chingyg]

or you can do a "roll your own" diac.... like so..... just use complementary transistors

Where do I use this?

 

[unclejed613]

X2 it's been years since i built a diac using transistors, so i don't remember how to adjust the breakover voltage..... oops, i drew it wrong.... the collectors are connected to the bases and the emitters are at the ends..... like this
and that's actually a Shockley diode (not Schottky). you make a diac by wiring 2 of these together parallel and reversed.

 

[tcmtech]

Just build it and leave the design alone!
Its simple and it works. And it works because its simple!

I would recomend starting with a 2 uf mylar capacitor for C1 and the lowest wattage light bulb you can find for R1 (like a 4 watt refrigerator bulb)

Once its built and then if it breaks down then worry about changing it!
Not before!

 

[tcmtech]

I think you just drew an SCR equivilent unclejed613.

 

[Willbe]

A Diac "snaps" over, an MOV doesn't. You need the snap action to get the e=-L (dI/dT) effect.

 

[unclejed613]

the SCR equivalent would be the same device with the trigger input on one of the B-C connections. other than that, they are the same device. the diac is like 2 of these devices back to back and all if the internal p regions wired together and all of the internal n regions wired together (which makes me think i got the internal bridging between the shockley devices backwards..oops again....).). interesting silicon equivalent of a gas discharge tube, and SCR's are a silicon implementation of a thyratron tube (gas discharge tube with a trigger electrode). i've seen pictures of BIG SCR's rated at almost 1900A that are 3" diameter. they replace thyratrons and ignitrons that were the size of a refridgerator.

 

[tcmtech]

I've got a whole pail of "hockey puck" style SCR's. Some are rated at 2500 Volts 2200 amps!

And as far as the SCR trigger circuit. Just use a mini neon bulbs. All you are doing is triggering the SCR gate with them. There is no point in over complicating it.

 

[unclejed613]

i still think it's better running the coil at it's self-resonant frequency. it's more efficient, and you get a much higher output current, as well as higher voltages.

 

[chingyg]

Just build it and leave the design alone!
Its simple and it works. And it works because its simple!

I would recomend starting with a 2 uf mylar capacitor for C1 and the lowest wattage light bulb you can find for R1 (like a 4 watt refrigerator bulb)

Once its built and then if it breaks down then worry about changing it!
Not before!

Ya, I'll get on it as soon as I got the money, which means getting rid of that kg of ANAL in my room. Sell it to some anarchist or something.

 

[chingyg]

I've got a whole pail of "hockey puck" style SCR's. Some are rated at 2500 Volts 2200 amps!

And as far as the SCR trigger circuit. Just use a mini neon bulbs. All you are doing is triggering the SCR gate with them. There is no point in over complicating it.

Exactly, why you make life complicated. and neon lamps are cheaper.

 

[chingyg]

Guys I know it is really dumb, I got 2 coil, but at the HV there is just this huge socket, How do I get a wire in there? besides breaking it apart?