Power on delay circuit needed

[Thomas]

I need a simple 2-10second delay circuit. When power is supplied, I need it
delayed. Will a 555 delay in that manner? Needs to be simple and no
relays. Whatcha got?

Thanks in advance.

 

[Rich Webb]

I need a simple 2-10second delay circuit.

Variable between 2-10 or fixed, roughly in that range?

When power is supplied,

power = ?

3 VDC, 300 mA for a flashlight bulb?
12 VDC, 200 mA to run a PC fan?
120 VAC, 1 A for a reading light?
750 VDC, 800 HP marine motor?

 

[Thomas]

12VDC @ 100mA should do it. Thanks.

 

[default]

12VDC @ 100mA should do it. Thanks.

Will sinking current work? The 555 is always an option.

A simpler approach is just a NPN transistor emitter to ground,
relatively large electrolytic cap on base to ground, relatively large
resistor charging the cap from +12.

To reset the circuit quickly, a reverse biased diode to the cap and
+12 will discharge the cap faster.

Works much better with 2N7000. That's an N channel mosfet with a pin
out similar to other TO92 NPN transistors. It requires a ~4 volts on
the gate to turn on so you get a longer delay for the same RC network,
the reset diode works better, it has lower leakage.

Very handy part that 2N7000 . . . and cheap.

 

[Thomas]

With the 555, in what config would allow me to pause for x-seconds then go
high until V+ is lost?

Thanks.