Remote power-on and reset gadget

I often want to be able to work on my projects when I'm away from my home lab.

So I was looking for a solution, or gadget, that will switch power to my projects and generate a reset signal when software bugs freeze my creations.

While researching the possibility to build or buy USB-controlled relays, I found this device in a surplus store:

It was missing the 10-pin header connector, and was tossed as bad.

After a quick web search to figure out what this was and $5 ... I took it home, replaced the header, downloaded the software and presto. I now have a USB to GPIP / I2C / SPI device, which is much much more than I asked for.

I put together an opto-isolated relay card controlled by the GPIO pins, and built this 2-relay power control and Reset gadget (schematic attached in PDF below).

• Power is supplied by a 5v/2A USB power supply
• The bottom relay switches 5v to the project I want to power, or a different external power source
• The top relay provides a normal-open or normal-closed contact.
  • These are used to momentarily short the reset button terminals, generating a reset state.
• The AARDVARK device is isolated with a pair of opto-isolators (top left)

Here it is connect to the TotalPhase AARDVAK, and to my latest project-in-progress. Supplying it with 5v and providing a reset signal (red and black wires):

The remote control component of the project is done with a simple Python script that uses the AARDVARK libraries and a VPN setup into my server.