Timed Delay Off circuit.

[reinchua]

Hi guys,,
can some one help me to design a circuit of a off timer circuit, the application im going to use is for the AUX fan. I need the aux fan to be running when the supply is cut off for a minutes like 10-15 before totaly off, then when the supply comes back, the timer will reset and it will remain standby and the aux fan will run again, as long as the supply is live the timer will ramain standby until the supply is cut off then the timer start to delay the aux fan to be off.

 

[MikeMl]

What is going to power the fan when the supply is shut off?

 

[KMoffett]

The circuit would depend on what your power source for the delay circuit and the fan is...AC?...DC?
You can Google either: delay on break circuit or delay off circuit

Ken

 

[reinchua]

Hi Ken,

The source of the AUX fan is also 12Vdc, i found the circuits, but i need the delay to be 10-15 min before it turns off completely the AUX fan. or can any one show me to a wiring diagram using the timer relay, instead of solid state parts.

 

[KMoffett]

Are you looking for an off-the-shelf module?

Ken

 

[raihan84]

Hi guys,,
can some one help me to design a circuit of a off timer circuit, the application im going to use is for the AUX fan. I need the aux fan to be running when the supply is cut off for a minutes like 10-15 before totaly off, then when the supply comes back, the timer will reset and it will remain standby and the aux fan will run again, as long as the supply is live the timer will ramain standby until the supply is cut off then the timer start to delay the aux fan to be off.

Hello reinchua, Can you explain a little bit in details what u want to do ?

when supply will cut off then how can that fan run? yes it can run due to inertia but not using power. If u want to add another power supply for that AUX fan then its ok.

 

[reinchua]

hi raihan84,

the purpose of the aux fan is for the cooling of a aircon condensers, then i added a 12Vdc aux fan. when the aircon kicks in the AUX fan must start too, but when the aircon stops, the aux fan must keep running for a 10-15 mins before it completely shuts off, i need the condensers to be cooled ASAP coz if the condensers are still hot the aircon wont starts. the aircon runs at 12Vdc and the aux fan that i added also runs at 12Vdc, i need a circuits that controls the relays that connected to the aux fan to cause a delays of supply cut off before it stops the aux fan completely.

 

[KMoffett]

So, the 12V power source is always there. Do You have access to the relay(s) that controls the main fan and/or the compressor?

Ken