For a project I'm working on, as soon as I apply 5v to a relay, I want a delay of about 1 second before that relay turns on, and stays on
as long as the power is present.

When power is removed, I want that relay to turn off fast. If power is immediately applied again, I need it to require another second
before the relay turns on again.

I tried a big electrolytic cap, with a resistor from the power, thinking it would take a while to charge up enough to pull in the relay,
but it isn't working the way I hoped.

Is there a simple way to do this? I'm working with 3.7 volts, and it's enough to turn the 5v relay on, but no more. I don't want to use a one shot 555 circuit if I can help it.

(edited for clarity)

 

Is there a simple way to do this? I'm working with 3.7 volts, and it's enough to turn the 5v relay on, but no more. I don't want to use a one shot 555 circuit if I can help it.
(edited for clarity)

Verified using 5 volt relay; Songle SRD-05VDC-SL-C

 

Thank you. Not sure if I have BS170...

Can I parallel two 2n7000 as equivalent for BS170?

 

One 2N7000 should be fine as the relay I used only draws appx 50ma at 3.7 volts.