FW: FW: [Elecraft] OT Need circuit help please

[Dan Barker]

Interesting application, to say the least!

If you can short the supply when not in use, the recovery should be quite
fast. I was jinking around at 5V, and forgot to try at 12V. Maybe the
transistor will stay on longer (I doubt it) at a higher voltage, but a
500mfd should get you your 250ms with the 35-45K/1M divider.

Let me know if you need me to get a better set of values. The 'scope and
breadboard are still set up, but the phone rang, I got hungry, the bus was
late, I had a flat tire, I wasn't my fault, I didn't get around to using the
"real" issues; 12V and 250ms.

Are you SURE this is off topic? I got to play with my calculator, DVM and
O'scope<g>.

Dan / WG4S / K2 #2456


Geoff sez:

dbarker@visioncomm.net writes:

btw, what is the application?

I have a printing business. We have an old large paper cutter. We had an
automatic
electronic spacer retrofit in 1983. Due to an electrical outage on a pole
outside, it
no longer works and the electric company is buying me a new one due to their
switch failure.

The new one allows me to turn on the air table which makes the large piles
of paper
easier to move with a +12VDC on when the backgauge moves forward or back,
user
selectable. But the old cutter requires only a pulse to turn on the air
table and if the
voltage is maintained, it cannot be turned off when we want it to be.

This should do it. Will take the parts home this weekend and get it going
pronto.

Thank you very much for the ideas. My mind is in the wrong place today.

Geoff, K6TFZ