Automatic Power Control of PC Peripherals via a USB

[rgsparber]

Would you like to have all of your peripherals turn off when you turn your PC off? Even with minimal skill in electronics, you can build this power controller.

If you are interested, please see

https://rick.sparber.org/AutomaticPowerControl.pdf

Your comments are welcome. All of us are smarter than any one of us.

Thanks,

Rick

[mklotz]

Thanks for the tip on the 5V relays.

My problem was very similar to yours and I solved it in a different, though not in any way superior, way.

Since I very seldom use my printer, I like to keep it powered down until I actually need it in order to save energy. Since it's use is so infrequent, I often forgot to turn it off after a session at the computer.

I bought one of those sets of three radio-controlled outlets, e.g....

https://www.amazon.com/Century-Wirel...s%2C219&sr=8-4

Outlet 1: controls power to a fan across the room (don't like it blowing straight into my face)
Outlet 2: controls power to computer, monitor, external hard drive, etc.
Outlet 3: controls power to printer

The system is turned on by pressing switch #2 on the remote that sits on my desk. If I need the printer, I press switch #3 .

I've trained myself to always power everything down by pressing the "all off" switch on the remote. Thus the printer gets turned 'off' whether it was on or not. This arrangement has also prevented me from leaving the (very quiet) fan on when I leave the room.

[DIYSwede]

Thanks for a nice, simple and cheap tip!
Q: -Are US connectors standardized when it comes to phase and neutral prongs on your plugs (and outlets)?

Over here in Europe, (and particularly here in Sweden)-
a code-abiding and pertinent safety factor would be to make a 2 pole switch,
breaking both the neutral and phase connector,
whilst keeping the Protective Earth connected at all times.

That could easily be done by putting two relays side by side, fired in parallell by the +5 VDC,
one for the Neutral conductor, the other one for the Phase lead.

Having a single pole breaker, and the relay's contact (inadvertently or erroneously) plugged to the neutral,
would mean that the outlet socket (and the appliances downstream) still carry full phase voltage, and could potentially be harmful.
The single breaker just opening the neutral line - and given a electrical fault of anything connected to it
the current could go through (you or anybody you care about, via) another appliance, a sink or any other grounded conductive object.



2 cents

Johan

PS: -Don't even think of giving one of these to any in-laws for X-mas!

[rgsparber]

Thanks for a nice, simple and cheap tip!
Q: -Are US connectors standardized when it comes to phase and neutral prongs on your plugs (and outlets)?

Over here in Europe, (and particularly here in Sweden)-
a code-abiding and pertinent safety factor would be to make a 2 pole switch,
breaking both the neutral and phase connector,
whilst keeping the Protective Earth connected at all times.

That could easily be done by putting two relays side by side, fired in parallel by the +5 VDC,
one for the Neutral conductor, the other one for the Phase lead.

Having a single-pole breaker, and the relay's contact (inadvertently or erroneously) plugged to the neutral,
would mean that the outlet socket (and the appliances downstream) still carry full phase voltage, and could potentially be harmful.
The single breaker just opening the neutral line - and given an electrical fault of anything connected to it
the current could go through (you or anybody you care about, via) another appliance, a sink or any other grounded conductive object.



2 cents

Johan

PS: -Don't even think of giving one of these to any in-laws for X-mas!

Johan,

Yes, power plugs are standardized. For 120VAC, it is acceptable to just disconnect the hot side of the circuit. For 220VAC we have two hot leads plus a neutral and both sides must be disconnected. It is against code to every switch ground or neutral.

Although you could use two of these relays, double pole single throw (DPST) relays are common.

"don't even think of giving one of these to any in-laws..." - very good advice. I didn't know you had met them ;-) This reminds me of a review I read on an iPhone wireless charger: "I give the product 1 star because it is not wireless. You have to plug it in..."

May you stay well.

Rick

[DIYer]

Thanks rgsparber! We've added your Automatic Power Outlet to our Extension Cords category,
as well as to your builder page: rgsparber's Homemade Tools. Your receipt:

Automatic Power Outlet by rgsparber

tags: electrical

[jdurand]

Thanks for a nice, simple and cheap tip!
Q: -Are US connectors standardized when it comes to phase and neutral prongs on your plugs (and outlets)?

Over here in Europe, (and particularly here in Sweden)-
a code-abiding and pertinent safety factor would be to make a 2 pole switch,
breaking both the neutral and phase connector,
whilst keeping the Protective Earth connected at all times.

That could easily be done by putting two relays side by side, fired in parallell by the +5 VDC,
one for the Neutral conductor, the other one for the Phase lead.

Having a single pole breaker, and the relay's contact (inadvertently or erroneously) plugged to the neutral,
would mean that the outlet socket (and the appliances downstream) still carry full phase voltage, and could potentially be harmful.
The single breaker just opening the neutral line - and given a electrical fault of anything connected to it
the current could go through (you or anybody you care about, via) another appliance, a sink or any other grounded conductive object.



2 cents

Johan

PS: -Don't even think of giving one of these to any in-laws for X-mas!

At least in the US there's a problem with using two relays, what if one sticks? You should have the two poles mechanically ties together so either they both go or neither (so you know there's a problem).

For higher reliability, relays are used with two series contacts for each pole. The series contacts being on a teeter-totter so if one sticks the other one being open tilts the bar and breaks it loose.

[DIYSwede]

At least in the US there's a problem with using two relays, what if one sticks? You should have the two poles mechanically ties together so either they both go or neither (so you know there's a problem).

Sure - Re 2-poles: Of course they're preferable. I was commenting a post having a few 1-poles around -
and using two couldn't possibly be worse than just one, given any malfunction?

2-poles ARE less susceptible, but no guarantees are given even in the higher current ranges, as I showed here last fall:
Circuit breaker cutaway - photo

After my summer vacation with thunderstorms a few years back I realized some 35 % of all (70-ish) GFCI panel breakers had gone AWOL at work,
frozen in the (NOT kosher) ON state... The should trip OFF...
Darned things wouldn't trip under any tried methods...

Free tip: -Test by pressing the button of your GFCIs occasionally...
Also a fast check for incoming voltage at sub-panels; No voltage present, then no trip.

Good luck with your sell and move, jdurand!

Cheers
Johan

[rgsparber]

Johan,

Thanks for the life saving tip. I will test them all today and set a reminder to do it each year.

Rick