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:

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2 responses

28 03 2010
FAMULUS

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.

Terminals:

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.

Simon

28 03 2010
FAMULUS

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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