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?
12 v relay
Oct 06, 2005
4 Replies
"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
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.Ed
thanks guys.
--- Do you want the relay to:
- Turn on some LEDs immediately after you turn the switch on and then drop out even if the switch is still on?
- Wait for a while after the switch is turned on before it (the relay) turns the LEDs on and then turns the LEDs off as soon as the switch is turned off?
- Something else.?
If you'd tell us exactly what you want we'd be in a much better position to give you what you need.
-- John Fields Professional Circuit Designer
Join the Discussion
Have something to add? Share your thoughts — no account required.
Didn't find your answer?
Ask the community — no account required