New Arrivals

27 03 2010

Some alligator clips for the FLUKE voltage meter.

Parts for the coil power supply:

SCR (844-VSKH91/14P). Not sure how to wire this up.

SCR schematic:

Rectifier + spare

Power resistor to bleed the capacitors:

Protection Diode + spare:

More conflat gaskets:

Back plates for 8″ conflat harware. These make installing conflats much easier needing only one wrench:



2 responses

28 03 2010

I asked M.Simon how to wire up the SCR. He replied:

That is WAY more SCR than you need for pulses. In any case.


1. To Capacitor bank
2. Coils
3. Ground
4. Trigger

The gate pulse needs to be 5V to 12V with a fast (a microsecond or faster) rise time. It should be delivered from a .1 uF ceramic capacitor. Do you have a spec. for the SCR? I could tell you more.

One side of your trigger coil goes to ground. The other side to the gate. If you put your trigger coil between terminals 3 and 4 you will get a big kick back (600V) into your trigger circuit from the turn on of the SCR.


28 03 2010

M.Simon adds:

After looking at the SCR specs I’d up the trigger capacitor to .33 uF or even to 1 uF. Ceramic. Put a number of .1 uF caps. in parallel.

It is a matter of turning on the SCR fast enough so that you don’t get a hot spot from partial turn on.

And if you burn this SCR out – get a 25A (TO-220/TO-247 package) job. For short pulses they are adequate and easier to turn on. And they are cheap.

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