10-50ma range. > >> >> > >> >> A simple on-delay timer would work but I'm having trouble finding one with NC contacts. Tons of stuff $100+, but for this application, it has to be under $20. > >> >> > >>
wanted to put something together from components but my brain is too far behind these days. I'm going to give this a shot and hopefully I'm not picking the wrong one. It's $5 at Frys... > >> > > >> > Velleman MK111 >
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5 > >> sec, the output would go high for 5 sec, and then drop to 0. If the > >> input droped before 5 sec was up, you wanted the output to drop as well. > >> Then you wanted it to wait until the input went high again before doing > >> that again. > >> This device has a relay (why would you need a relay for 50ma? Most ICs > >> can handle an ouput current of
50mA at 12V without the need of a relay. > >> > >> This kit is an oscillator, where you can adjust the time it is on and the > >> time it is off with the pots. It has no input. > >> > >> It uses a 555 timer chip. The primary design of the 555 is to initiate a > >> pulse when the input goes high, and stays high for the requsite time > >> even if the input drops again. If the input stays high beyond the time > >> Ie, I think you want to think your way through what you need carefully. > > >
RV1 to give a pause time between pulse to 10 minutes? > > RC=t roughly. (depends on exactlywhee in the charge/discharge cycle the > thing triggers). But R probably should not be much over 1Mohm, as > otherwise the input resistance of the ic becomes important. > Then C should be about 600uF (probably not electrolytic as the internal > resistance can become important but finding anything else at that size > is pretty impossible) - Thanks. I think I'll put a fixed 2M ohm in series and see if I can get a 3-5 minute range.
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If I disconnect pin 7, would that make it a one-shot pulse?
Jeeeeeze, If you'd have bought the damn Altronix 6062 you'd have been up and running in 15 minutes instead of EF-en around with this $5.00 piece of crap.
I just don't understand some people I guess.
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Time is not a big deal for me. This is more of a learning project for me.
seconds. Then output will go back off and stay off until the input goes to zero. Then cycle starts again.
one with NC contacts. Tons of stuff $100+, but for this application, it has to be under $20.
something together from components but my brain is too far behind these days. I'm going to give this a shot and hopefully I'm not picking the wrong one. It's $5 at Frys...
Well, I made a real mess of the first board, thanks to a new Weller soldering iron. Ended up digging out my old Radio Shack iron which worked 10 times better - same type and wattage as the Weller. Here's the soldering job on each board....
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Anyway, I made the changes Spehro mentioned and it works perfectly!
First I snipped the R3 out of the circut which caused the LED to act as a one-shot as needed. So with that good news, I added the jumper and now the relay is in the circuit and I am in Fat City!
FYI, on the left is the assembled board from the kit. Right shows it with the jumper added.
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Thanks again to all for this very educational journey!
Get a sensitive relay (coil 1k ohms or so), put about a 3ooo uf capacitor across the coil, apply 12 volts to the coil, the relay will hold closed while the cap is discharging into the coil. Use the n/o contacts to do what you want.
John Sowden American Sentry Systems, Inc. San Francisco Bay Area
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