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circuit design requested

Where can I ask for something like this, I want a circuit that will allow me to sent a countdown timer via a numeric keyboard that will control a camera shutter. The interface to the camera is pretty easy. A small audio type plug and connection made with two leads. What I want to do is have a small numeric keyboard and a red LED display that, once the time is started, will make the connection, opening the shutter, counts down from the set time and upon arriving at 0, breaks the connection closing the shutter. Audible alarm before countdown finishes would be good.

Where, if not here, can I ask for a fairly simple circuit to do this?

Thanks.

Reply to
Jack
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Do a search for bomb timers and replace the ignitor with a relay for the shutter.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

With one exception, what's described is just like a darkroom timer, the kind that switches on the light of an enlarger to make a photographic print. Digital photography is taking over, so there are lots of darkroom timers on the used market.

The exception is, the darkroom timer closes a switch that connects AC power; you can just rewire that switch to connect your low- voltage wires instead.

Reply to
whit3rd

Westbend kitchen timer. Get into the case, go across the little "sounder" or speaker, pull out the signal, use it to drive a transistor to pull in or out a relay.

We used this exact system for the Voyager around-the-world-on-a-tank-of-gas fuel tank timer to light up an orange light when it was time to swap tanks.

We called the engine monitor (sophisticated idiot light) the Voyager Instrument Official Little Engine Thingy (VIOLET) and the timer the Tank Interval Timer To Insure Engine Success (TITTIES). We labeled it prominently VIOLET TITTIES but they made them sand it off when it went to the Smithsonian.

The copilot, Jeana Yeager, wasn't all that thrilled with it either {;-)

Jim

-- "If you think you can, or think you can't, you're right." --Henry Ford

Reply to
RST Engineering (jw)

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Reply to
Tom2000

The simplest circuit will most likely center around a single in-circuit programmable PAL, say from Lattice. You are scrounging which means you use what you can find.

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has low priced keypads. Your post indicates you are gizmo-centric and not electronics oriented. You're probably way over your head thinking you can build anything like this, so an ebay buy of an antiquated darkroom timer will get you to where you want to be in the least time at least cost and trouble with maximal probability of success.

Reply to
Fred Bloggs

Fred Bloggs wrote in news: snipped-for-privacy@nospam.com:

A micro might be easier for a novice. Especially something like a Basic Stamp, which this project calls out for.

Reply to
Gary Tait

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