- My USB-switchable Powerstrip -


We have a small server running at home for minor tasks ( like remote surveillance and document-server ).
Unfortunately our internet provider tends to terminate the connection randomly, which requires manually
restarting the DSL modem. If we are at home, this only poses a "minor" inconvenience, but when on the
road, this pretty much shuts down our access to our "home". Since the only way to solve this - per our
provider's instructions - is via power-cycling the modem, I had to come up with automating this...
Combining the USB Bit Whacker (UBW) board with relays and a modified powerstrip was my answer.
The USB side is connected to the server ( Ubuntu Linux ) and I wrote a small program which
checks if there is internet access via the ping protocol at 15 minutes intervals.
Detecting an outage, it powercycles the DSL modem and the Access Point. Problem Solved.
The left 2 outlets can be turned on/off via the USB Bit Whacker. The outlets are ON
by default with relays at a resting position ( minimizing fatigue and power consumption ).


It actually looks pretty non-Frankenstein...



A solid-state relay (SSR) is driven by the UBW which in turns drives a 30A electro-mechanical (solenoid) relay.
(2x15A parallel) Both relays work with 120V, so no extra power supply is needed.



I cut the copper sheet inside the powerstrip and reconnected them via the solenoid relays.
I wired the solenoid coils to the solid-state output terminals in a serial manner, so that
when the SSR closes, current flows to the solenoid closing the controlled circuit
which in turn interrupts the current to the outlet :





I put the UBW (from sparkfun) in an enclosure (from Fry's) to protect it.



Connected 2 of the output ports on dual wires.



Connected the wires from the UBW to the solid-state relays' control inputs,
than insulated the exposed connectors with tape and put the power strip back together.



Plugged in the DSL modem and the Access Point to the controlled outlets.
As mentioned above, the small program I wrote uses ping to check internet
connectivity and in case of failure it powercycles the modem and AP with
some delays between the two. It also logs all activities to a log file...


Go back to the Home Project page.