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Circuits Miscellaneous Power-On Time Delay Relay
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Circuits Miscellaneous Power-On Time Delay Relay
Power-On Time Delay Relay
Here's a power-on time delay relay circuit that takes advantage of the emitter/base breakdown voltage of an ordinary bi-polar transistor. The reverse connected emitter/base junction of a 2N3904 transistor is used as an 8 volt zener diode which creates a higher turn-on voltage for the Darlington connected transistor pair. Most any bi-polar transistor may be used, but the zener voltage will vary from about 6 to 9 volts depending on the particular transistor used. Time delay is roughly 7 seconds using a 47K resistor and 100uF capacitor and can be reduced by reducing the R or C values. Longer delays can be obtained with a larger capacitor, the timing resistor probably shouldn't be increased past 47K. The circuit should work with most any 12 volt DC relay that has a coil resistance of 75 ohms or more. The 10K resistor connected across the supply provides a discharge path for the capacitor when power is turned off and is not needed if the power supply already has a bleeder resistor.
Copyright 2006: Bill Bowden
Copyright 2006: Bill Bowden
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Apr 14 2007 7:51
JBWilliams
Mr. Bowden:
I am NOT an electronic circuit designer, which is why I ended up browsing your WEB-site. Although I do understand the 555 circuits presented here, I didn't find any of them to be exactly what I am looking for. Hopefully, if I detail my requirement to you, you can either provide me a schematic, or perhaps a link to what I am looking for.
Here's what I am looking for: Upon applying 120VAC to a modular power supply that delivers +5VDC or +12VDC, there is a 3-second delay and then the first of either an electro-mechanical relay, an opto-relay or a triac is activated that turns on a 120VAC circuit at 12-Amps. After an additional 3-second delay, a second relay is activated. And finally, after an additional 3-second delay, a third relay is activated. Three relays in all, each delayed by 3-second intervals, including the initial power-up.
I would be GREATLY appreciative if you could supply me with such a schematic. I've been searching for a circuit like this for quite awhile. You can reach me at: jbwilliams_designer@yahoo.com
Thank you very much in advance for your assistance.
Regards,
JBWilliams
/
I am NOT an electronic circuit designer, which is why I ended up browsing your WEB-site. Although I do understand the 555 circuits presented here, I didn't find any of them to be exactly what I am looking for. Hopefully, if I detail my requirement to you, you can either provide me a schematic, or perhaps a link to what I am looking for.
Here's what I am looking for: Upon applying 120VAC to a modular power supply that delivers +5VDC or +12VDC, there is a 3-second delay and then the first of either an electro-mechanical relay, an opto-relay or a triac is activated that turns on a 120VAC circuit at 12-Amps. After an additional 3-second delay, a second relay is activated. And finally, after an additional 3-second delay, a third relay is activated. Three relays in all, each delayed by 3-second intervals, including the initial power-up.
I would be GREATLY appreciative if you could supply me with such a schematic. I've been searching for a circuit like this for quite awhile. You can reach me at: jbwilliams_designer@yahoo.com
Thank you very much in advance for your assistance.
Regards,
JBWilliams
/
Apr 16 2007 12:04
Jospfh
Hi JBWilliams,
I created an account for you and moved your question to the forum (as if you have been posting it)
Regards, Jospfh
I created an account for you and moved your question to the forum (as if you have been posting it)
Regards, Jospfh
May 30 2007 17:31
Dale
what wattage are the resistors?
Jul 6 2007 4:23
LING
CAN I USE THE 555 TIMER IC
TO MAKE SOME DELAY ON THE CIRCULT
ON 24 V AFTER 15 SEC DELAY 24 V GO TO CIRCULT!
TO MAKE SOME DELAY ON THE CIRCULT
ON 24 V AFTER 15 SEC DELAY 24 V GO TO CIRCULT!
Jul 25 2007 9:53
Jospfh
Hi Ling,
I would suggest to use a LM7812 to bring the voltage down to 12V.
Regards, Jos
I would suggest to use a LM7812 to bring the voltage down to 12V.
Regards, Jos
Aug 7 2007 11:34
sarahoc
Hello, nice site! My site
----Links removed by Jospfh. Please not spam this site with unrelated links!----
----Links removed by Jospfh. Please not spam this site with unrelated links!----
Oct 21 2007 1:22
leah
heloo..
is this the the same circuit of power on delay and low voltage protector for appliances compressor type???? it has LM555, 12relay, but its is for appliance use???
is this the the same circuit of power on delay and low voltage protector for appliances compressor type???? it has LM555, 12relay, but its is for appliance use???
Oct 22 2007 9:58
Jospfh
Hi leah, I do not understand your question, can you be more clear in what you question is?
Jan 29 2008 9:10
Tarth
how can this curcit run off of 9volts?
it won't. i need it to trigger at 6.3~7 volts mesured across the zener setup trnasitor, im using the 2n3904.
it won't. i need it to trigger at 6.3~7 volts mesured across the zener setup trnasitor, im using the 2n3904.
