12 v relay

is there a widely available 12 v time delay relay? what i need is a relay that will run between 30 seconds to 1 min, (or anywhere in between) to run a low amperage circuit (a few leds). anyone got any ideas?

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"redls1bird" schreef in bericht news:opednbVs74lRfNneRVn snipped-for-privacy@giganews.com...

I remember old dokatimers did this things although they switched mains powered bulbs. Never heard about others ever since. Think you can easily build one yourself using a 555 timer.

petrus bitbyter

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petrus bitbyter

Here's a simple circuit:

+12 ---+----------------------+-----+ | | |k +--o o--+ [RLY] [D1] 1N400x S1\\ | | | [10R] +-----+ | | | /c +--------+---[3.3K]---| Tip120 | | + \\e [POT]20K [C1]4700uF | | | | Gnd ---+--------+-------------+

The pot can be used to set the time delay. When you close S1, the relay will energize. When you open S1, the relay will remain energized until the capacitor discharges to approximately

20% of Vcc (about 2.4 volts in the circuit shown). With the values shown, the delay time range should be from 0 to over 1 minute. The exact range will depend on the transistor gain and the relay coil resistance.


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Do you want the relay to:

1. Turn on some LEDs immediately after you turn the switch
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John Fields

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