Electronic – Delay current flow


I'm trying to achieve something seemingly simple. I have a contact (button) that I upon pressing should wait a few seconds before actually allowing current to flow through. For this purpose I'd need some expensive button that I'm not really sure I will find, or I need to just put another component after the button that does the delay part. I searched for such components but without luck.

Is there any component that will allow me to delay current flow by couple seconds and then conduct as if it were just an ordinary conductor?

Best Answer

One way to handle this is have the button be a input to a tiny microcontroller, then have that micro control a relay. The micro does the timing and possible de-glitching of the button.

The cheap and tiny PIC 10F200 can do this easily. It comes in a SOT-23 package, which is the same package individual transistors come in. The button can be wired to a input pin directly, since some pins can be configured with internal weak pullups. The output could drive something like a logic-level N channel FET, which would enable the relay.

All together, the total parts would be:

  • Pushbutton.

  • Microcontroller.

  • Bypass cap for the micro, like 1 µF 10 V ceramic.

  • N channel logic-level MOSFET, like IRLML2502.

  • Relay.

  • Reverse diode across the relay coil, like 1N4148.

Related Topic