Sequential switching of units.

Linear and non linear

Sequential switching of units.

Postby chrismb » Thu Jun 02, 2011 2:14 pm

If you have 10 modules you want to power up, and you want to have a way to power 1 of them, or 2, or 3, etc., is there a 'standard swith-type' or some 'standard' way of doing this?

For powering a row of DC items, I thought of a rotary switch in which there is a diode between the lines for each unit, so as you rotate the switch the power feeds all below that selector position. But that means that you have to put in bigger and bigger current spec for the diodes, because the top-most one may have to feed all the modules. Doesn't sound a very efficient use of diodes.

Any thoughts? {please let me know if my question isn't very clear!}
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Re: Sequential switching of units.

Postby Doug Coulter » Thu Jun 02, 2011 2:27 pm

I just use a row of good quality toggle switches myself. Not only can you just slide a finger down the row if wanted, but you're not restricted to sequential or "all up to here". Or DC for that matter. As you point out, the diodes have issues -- and in my case an ever increasing loss due to forward drop would kill my instrumentation accuracy for all the stuff I have running off the same DC supply as well.

I use the high quality mil spec toggles, the tiny ones that nevertheless have high amp ratings, and which have a positive "snap" when switched. They seem to last forever if you snub any real reactive loads.

I'm using such a row setup now on the big fusor for things like pumps power, bakeout power, instruments power and main HV power. Some of them are 3 way, as in my forepump control, which has auto, off, on positions. In that case, auto means it runs the forepump whenever the turbo draws more than a set wattage. Bakeout heaters have a low, off high setup as well. Costs a little more the first time but seems worth it to have the flexibility in something otherwise hard-wired.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Doug Coulter
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