#14 Experiments with Plasma Ignition

[Cacio90power]

why only one diode?? can you post the schematic-iìm trying with plasma too..

[PainlessHHO]

There are eleven diodes, the single is just to stop the AC reversing. Private message me your email address and I'd be happy to email you a schematic.

[onecraftydude]

Just for information purposes, I use 1000 vdc diodes # 1n 5406.

[PainlessHHO]

I ordered some 1N5408 1000v 3a diodes from bgmicro the other day, hopefully, these will do the job!

[onecraftydude]

Did you have a short circuit? The only time I blow diodes is when I short the a/c side at the spark gap. Usually it is from slag buildup on the plug. The other way I burn diodes is when I spark the plug too fast, but that usually melts the solder joint before it destroys the diodes. A good idea for protecting the diodes is to use a fuse between the diodes and the plug. I ran out of fuses at the show so I removed it from the circuit.

[PainlessHHO]

I'm thinking that my diodes are to blame, I've blown up two capacitors now, even my little 47 uf. I'm assuming that the culprit here is the hvdc getting back to the cap.

I remember you used an AC cap for your setup, what were it's ratings?

If I remember correctly, you used a common ground for all parts of your circuit? ...or did you isolate between AC and HVDC ground?

[onecraftydude]

I use an a/c capacitor for motor starting. You might be able to use others, but that one is designed to discharge fully. I use the 110 vac 300 uF caps. I have tried others and they worked too so I don't think it is the uF rating that matters as much as the voltage. Since the supply voltage is a/c the cap should be also.

Both a/c and d/c share a common ground on the circuit. I get feedback at my battery and I will probably install a diode at the ground later.

[jdcmusicman]

Looking good man ....pretty interesting stuff

[PainlessHHO]

Thanks jd, I've wanted to start some real experimenting with this stuff for some time now. Check out onecraftdude's plasma videos, they are very interesting.

[onecraftydude]

Great replication. I have explained this circuit so many times it makes my head hurt and you are the first to grasp the complete circuit, congratulations and good work.

I noticed you added the toroid on the positive leg of the a/c prior to ground. Have you tried the spark without it? My coil is located in the neg or common leg after the diodes. I guess the coil can be in either position without effecting the circuit. Can't wait to see the new rig when it's done, great job.

[PainlessHHO]

I haven't tried it without the toroid, from what I've read the inductor stops the AC side from wasting power while the capacitor is discharging. The current is stored in the coil until the capacitor needs to be refilled.

I managed to burn up my last diodes and only spark plug already. *sigh*

[onecraftydude]

The two voltages combine at the gap. Using slow motion photography you can see a charge develop on both sides of the gap.

[tjgame2]

Does the AC jump with the 12 volt spark , or does the 12 volt spark make a path for the AC , I dont understand.

[PainlessHHO]

Basically, the effect is the same as a lightening strike. The 12v side produces a 20-40 thousand volt potential between the two sides of the spark gap, this ionises the air, allowing the higher amperage, but lower voltage, AC side to jump the gap. The AC (which is DC by here) builds up on the negative side of the gap (again, just like a lightening strike, it travels from the ground to the air).

[tjgame2]

Thank you , that makes sense.

[PainlessHHO]

No problem, tj. Check out onecraftydude's plasma videos.

[HHOPWR]

Nice Russ, I am glad the coil is going to good use.

Larry