What is it?

This board passes low voltage DC power (up to 2.5A @ 20 VDC) from a source to a load, and it has an open-drain input (that is, you short it to ground to activate) that will cause the power to be dropped for ten seconds and then restored. The board has a microcontroller on it that will only permit the power to be dropped once per hour, as a safeguard against the controlling circuit malfunctioning.

This is perfect for creating a network monitoring watchdog for an unattended SOHO network router (just as an example). A Raspberry Pi can run scripts from cron to detect whether the network is operational and, if not, power-cycle the router. This remote monitoring and action can save a lot of trouble in situations where a device is unattended and having to reset it would be troublesome or expensive.

What makes it special?

While there are many other methods one could use - for example, a timer to power-cycle the device on a daily basis - the added value here is the intelligent gatekeeper that only permits the power-cycle to happen at most once per hour. Also, the design attempts to insure that any fault would result in the power state failing-on rather than off.

The power input is a center-positive 2.1mm standard barrel connector, and the output is a similar plug on the end of a 6 foot cable. The input is a 1/8" mono phone plug (tip input, ring ground). Short the input to ground for at least a second and the power will drop for 10 seconds. It won't drop the power again unless the input is de-asserted for at least a second and then not asserted again for an hour.