The schematic is correct but the mosfet doesn't look installed correctly on the breadboard.

Online schematic shows, when looking at its face; pins are 1-Drain 2-Gate 3-Source from left to right. Drain pin goes to relay pin and Source pin goes to Ground. Is this configuration correct?

 

Should be but can't see it that well on the breadboard,
Remove the larger cap and use just the 22uf.

 

Should be but can't see it that well on the breadboard,
Remove the larger cap and use just the 22uf.

I just removed the second capacitor and tried again. I also reversed the mosfet and relay still works instantaneous.

 

Appears then the mosfet is shorted. Install the mosfet correctly and connect the gate directly to ground to confirm if it's shorted.

 

Is there anything I can do about it ? I just bought it new today. Also did any of my wirings cause this? I want to learn to avoid further mistakes.

 

Not if it's shorted.
Possible it was bad when you bought it. Where did you get it from?
Do you have any BC337 transistors on hand? If so can try the other circuits.

 

Not if it's shorted.
Possible it was bad when you bought it. Where did you get it from?
Do you have any BC337 transistors on hand? If so can try the other circuits.

There is only one component store in my city and I will let him know of the bad mosfet. I want to build the other circuit but I don't have BAT54 diode and the exact 12.1k and 11k resistors at hand. Can i substitute them with 1N4007 and resistors with similar values?

 

I want to build the other circuit but I don't have BAT54 diode and the exact 12.1k and 11k resistors at hand. Can i substitute them with 1N4007 and resistors with similar values?

Yes. Do you have the 1000uf cap required?

 

Yes. Do you have the 1000uf cap required?

I have two 470 and I can connect them in parallel for 940 mF. I can get 1000 mF tomorrow.

 

For experimental purposes just use one 470uf for now and see how that works.

 

For experimental purposes just use one 470uf for now and see how that works.

It works! Current open time is around 5 secs and I will increase it with a higher capacitor. However, relay closes right away when I cut off the power.

 

It works! Current open time is around 5 secs and I will increase it with a higher capacitor. However, relay closes right away when I cut off the power.View attachment 328229

Of course you killed the power.

To simulate when the ignition is ON or OFF remove the diode or install a series switch.
With this circuit I was getting about 5 seconds both ON and OFF.

 

Of course you killed the power.

To simulate when the ignition is ON or OFF remove the diode or install a series switch.

Oh man, there is still too much to learn
I get the concept and will institute it in my oncoming projects. Thank you all very very much for the help. Especially you
sghioto and crutschow.

 

Hi guys, me again


I just made the circuit and it works beautifully when powered on. However it shuts off almost immediately after the power is removed. I used as much as 2000 mF capacitor but Off Delay seems to be indifferent. Can I use a resistor to limit the power drainage of capacitor to elongate the off time?

 

I just made the circuit and it works beautifully when powered on. However it shuts off almost immediately after the power is removed.

I don't think you wired the switch correctly.
This is a test circuit and the switch is wired to only simulate the Ignition ON and OFF.
12 volts is maintained on the collector of Q1 constantly.
Look again at the schematic below.

The circuit in the vehicle will look like this:

 

I don't think you wired the switch correctly.
This is a test circuit and the switch is wired to only simulate the Ignition ON and OFF.
12 volts is maintained on the collector of Q1 constantly.
Look again at the schematic below.
View attachment 330726
The circuit in the vehicle will look like this:
View attachment 330727

You came to the rescue again! Thank you, I will modify it accordingly.