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60 Second Time delay for photo cell LED's Answered

Ok here is my dilemma. I have created hallway lighting with leds using the same setup as the blue bawls photo cell lights Blue Bawls . so what i need now is a way to delay the "on" time of the leds for 60 seconds after i break the beam. The trigger is a laser pointed at the photocell so when i break the beam the leds turn on. its currently running on 7.5V dc. Any suggestions or schematics are greatly appreciated .

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AgentDanny (author)2006-12-14

Awesome. Thanks a bunch guys.

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LasVegas (author)2006-12-13

Just use a standard 555 timer circuit, available on any 555 chip data sheet. The time delay is calculated with the RC circuit as t=RC in seconds, so if you used a 1µF capacitor with a 60MΩ resistor, it would give you about 60 (0.000001 x 60000000) second delay.

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westfw (author)LasVegas2006-12-14

Here are some circuits with explanations a bit closer to english than the japanese site: http://home.cogeco.ca/~rpaisley4/LM555.html#30
Or Google: http://www.google.com/search?q=555+delayed+on

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AgentDanny (author)LasVegas2006-12-13

sorry im kinda new to electrical engineering. can you type out a parts list? in lam ans terms?

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