# Need Help With HV Diode Values

Discussion in 'General Electronics Chat' started by Livingwaters, Mar 4, 2008.

1. ### Livingwaters Thread Starter Member

Mar 4, 2008
16
0
Hello, and thanks for the replys.

This is what I am trying to accompolish.

We are conducting experiments involving the placement of a plasma spark at the spark plug electrodes on an internal combustion engine.

To do this, models have been constructed using a DC to AC power inverter to supply 110 volts 20 amps AC of current to the spark plug. The inverter is only grounded at the spark plug base. The plug gap keeps the pos and neg apart.

The standard ignition system on the car is left intact. So, we will have app. 34,000 volts DC at 0.83 amps firing to the plugs at intervals (while the engine is running) in addition to the 110 volts (constant) at 20 amps AC going to the plugs.

My question is: what values, based on the numbers I have given, should be used for the diodes in the circuit to prevent back feeding of the HV to the inverter and Car Distributor.

I will take a picture of the circuit diagram, (I don't have a scanner) and post it if needed.

Thanks in advance for the help.

Livingwaters

2. ### beenthere Retired Moderator

Apr 20, 2004
15,808
295
The circuit diagram would be really helpful. I'm trying to imagine what the 110 VAC @ 20 amps is doing. Does the spark plug have a maintained arc of 20 amps across the electrodes?

Any diode that can block the 34KV will also block the applied AC.

3. ### mrmeval AAC Fanatic!

Jun 30, 2006
833
3
Interesting. A diode would only block 1/2 of the AC.

You may have to use the car's HV as merely a signal to activate a circuit you design specifically to handle both voltages. Your circuit would generate both the 34kv DC pulse and supply the 120VAC 20amp voltage.