BYO Auto-Switching Power Strip

[crashwg]

I remember seeing sometime in the recent past on these boards something about a powerstrip that connected to a USB port and when it sensed power would then turn on the rest of the powerstip.  Only problem if I recall correctly was that it was not a US product and therefore had different curent/plug and would not be useable by those in the US.

So, I got to thinking... Shouldn't it be easy to duplicate the same results with off-the-shelf parts and ultimately have a working product?

Here's my thoughts.  Just let me know if I'm not on the right track.

Ok, so you've got a power strip, you would:
Open it up
Cut 1 wire that feeds the left/right side of all the outlets
Insert 5v/110v relay between cut (110v part obviously)
Attach 5v part to the end of a USB cord
Close it all up
Attach USB cord to PC
Done!

Does this make sense to anyone other than myself?
It seems to be a simple solution to a common problem.

Only thing that bothers me is posibly frying my USB ports.  
Is there any advice those with electrical experience would give me to avoid doing such a thing?  It would be greatly appreciated!

Thanks for your time, and if you feel like going ahead with this design feel free to do so as I wouldn't have to experiment on my computer.  

[krick]

Sounds like it would work.

In theory, you can tap 5V off of a USB port:
Pin 1 is +5V
Pin 4 is ground

I use an amplifier from a set of USB powered speakers in my mame cab.
Works like a charm.

The only problem that I see is that on some motherboards, the USB ports continue to remain powered even after the PC is off.  I don't know why, it may be a design problem or something.

[crashwg]

I use an amplifier from a set of USB powered speakers in my mame cab.
Works like a charm.

Would you care to elaborate on exactly what it is you're doing with the USB powered speakers?  I'm not exactly following you.  Have you done the relay/powerstrip thing with the speakers?

[krick]

I use an amplifier from a set of USB powered speakers in my mame cab.
Works like a charm.

Would you care to elaborate on exactly what it is you're doing with the USB powered speakers?  I'm not exactly following you.  Have you done the relay/powerstrip thing with the speakers?

No there's no relay involved.  I was mentioning that things (like speakers) can be powered off of the 5V supplied by a USB port simply as an illustration.

I'm just doing the standard "speaker amplifier hack" that most people do.  You know, buy a set of cheap computer speakers and gut them for the amplifer board inside.  However, the twist is that I've chosen a set of speakers that are powered off of a USB port instead of a power brick that you have to plug into a power strip.

See these threads for more information...
http://www.arcadecontrols.org/yabbse/index.php?board=1;action=display;threadid=16381
http://www.arcadecontrols.org/yabbse/index.php?board=1;action=display;threadid=20839

[koolmoecraig]

Why not just buy a SMART STRIP? They are under $30

http://www.bitsltd.net/smartstrip/buy.htm

[krick]

Because half the fun is trying to make it yourself.

You can get a power strip for $5 and a relay for less than $10.
So for less $15 and a little effort, you can make a "smart strip" type device yourself.

Plus, you get the bragging rights that go along with that....
"See that? [points at power strip-relay hybrid]...  I made it myself."

I'm fairly certain that most of the repeat posters here actually like working on thier cabinets more than actually playing games on them.

At least I know I do.  

[rchadd]

Why not just buy a SMART STRIP? They are under $30

because they don't work in the UK

i was thinking of implementing similar - but was going to usin one of the disk drive power connectors off the  ATX PSU to switch the relay.

[crashwg]

I'm going with USB due to the fact there will probably be a laptop in the cab for a good amount of time and I doubt the smartstip would work correctly with the way laptops consume electricity.  But I could be wrong...

But back on track.
Is there any harm in connecting the 5v from a usb cable to a relay?  Would a relay consume enough electricity not to cause a short?  Should I put an LED or a resistor in line just in case?

[crashwg]

So no one else has anything to tell me?

I REALY don't want to blow my USB ports!

[AlanS17]

Hook up a cheapo USB hub in-line. If anything goes, it should be the hub. Then you'll know!

[rchadd]

believe there are "opto-isolating" electronics components that are designed to prevent such harm.  but not sure how they would be used in your case.

[crashwg]

Anyone know where I could get a female ?B? end connector?  What I'm thinking is to not actually cut a usb cord for this project but put a socket in the powerstrip!!!  In case I'm wrong about the B part I'm looking for the end that's shaped like:

This
 __
 /   \
|__|

not This
_____
|____|

and again, a female connection (hole) so I can just insert a regular USB cable into the powestrip!

[CIA_Guy]

My concern would be that the relay coil might pull too much power.  Check the ratings on the relay and the specs for USB ports and make sure the port can handle the pull.  An cheap *powered* USB hub would probably prevent the destruction of the port if the relay pulls too much power.

If you really wanted to get fancy, look up a transistor trigger circuit -- an "all electronic" version of the relay.  (Someone here with an electronics background could probably draw out the circuit in a couple of minutes.)

Also, make sure you cut the "hot" side of the 110V circuit -- it should be the one running through the built-in switch on the strip.

BTW, cool idea......If I had a relay laying around I'd try it with one of the old PCs I've got.

[krick]

Anyone know where I could get a female ?B? end connector?  What I'm thinking is to not actually cut a usb cord for this project but put a socket in the powerstrip!!!  In case I'm wrong about the B part I'm looking for the end that's shaped like:

This
 __
 /   \
|__|

not This
_____
|____|

and again, a female connection (hole) so I can just insert a regular USB cable into the powestrip!

That's brilliant.

I'm not sure where to get a USB socket.  I'm sure one of the electronics places like "Mouser" will probably have them.

Or, you could always cannibalize the cheapest USB device with a detachable cord that you can find.  Like maybe a used USB printer from Goodwill or something.

That's what I'd probably do.

[crashwg]

Ok, so I've got this thing, it's got two of the sqare usb sockets but I'm not quite sure if I want to hack it up or sell it...

It's call "USB Direct Connect".  Manufactured by Belkin, it is used to connect two PCs together as an alternative to a hub/router/crossover cable.  It runs on USB (not 2) therefore it isn't exactly the fastest option when it comes to networking, but it sure is easy and even a child could do it with XP.

Here's a link to more info at Belkin's site.

CLICK ME

I'm also going to post this in the forsale forum and if I can get any good offers I'll likely scrap the plan of using this and move on to something else!

[crashwg]

Just to keep anyone interested informed and also to get a second opinion...

I contacted Mouser and asked them what I should use.  I told them exactly what I was planing on doing and gave them a general idea as to what I will be powering with the strip and they responded with the following products.

The best relays that may work would be p/n 528-9122-5, 528-9522-5 for pc mount or 528-9152-5, 528-9552-5 for flange mount.

All those products can be found HERE

I went ahead and ordered 528-9152-5.  It cost $3.12 + shipping, which I didn't catch how much that was.

Should be here in a couple days, then I have to go and get a power strip and we'll see from there!

Oh, and BTW, if you know anything about electronics and you think the part that I ordered may cause problems, please PLEASE let me know.  I don't want to break anything!

[crashwg]

Good news & Bad news.

First the good:
I picked up a powerstrip at Wal*Mart and it seems to have enough room inside for a relay and it looks straight forward when it comes to adding a relay.

And the bad:
For some reason my bank declined debit payment to Mouser.    I just got off the phone asking them to give it another go and I'm pretty hopefull that it will go through.  For the life of me I can't figure out why it didn't the first tome though...  I've got the money in there!

[crashwg]

YAY! My relay came today.

Now all I need to do is figure out what wires go where...

OK, so it's got 5 pins, well 4 realy, 1 has been cut off.

they are labelled as:

NC    - The cut off one
NO    - Large tab
COM - Latge tab
no label - Small tab
no label - Small tab

So, I'm thinking COM would be ground on the USB and NO will be the 5v+ and the ones with no labeling are for the 110v...  Sound about right?

I'm a little confused as to why the 5v tabs are larger than the 110's...

Anyways, I'm just going to post this in here for now, but if I don't get a response in a few hours I'll probably post this in it's own topic, so please don't guess.  Only reply with an answer if you KNOW the answer.  I don't want to blow nuthin up!

[CIA_Guy]

NO - the contact on the relay that is closed when power is applied (open when "at rest")
NC - contact that is closed w/o power (circuit is complete at rest)
common - the center contact of the relay that is at rest on against the NC contact and pulled down to the NO when power is applied
The other two -- the wires for the electromagnet that pulls the common contact down when power is applied.  

[JohnNevets]

Ok I'm trying to put CIA's coments into home electrical/my dumb a** lamens terms.  I think I understand it, but I may be completly wrong (I'm thinking of trying this myself, so I'd like to understand it).  

You take the hot side wire from the 110 plug cut it in two and hook the side closest to the plug up to the "NO" conector, you then hook the other 1/2 of the cut wire to the "common" connector.  The 5 volts from the usb conector can be hooked up to either of the small tabs, as can the ground from the usb conector.  

Now when you turn the computer on 5V DC should go down the usb cable activate the electromagnet and flip the spst switch and allow power to flow to anything you have plugged into the power strip.

So, Howd' I do? Do I understand it, will I fry myself, or would it do nothing at all.

Thanks for starting the post Crash.

[CIA_Guy]

JohnNevets:

You've got the 110V part right -- the common and the NO will be connected when power is applied to the relay.  When no power is applied, that "circuit" is broken -- "normally open."  Your description of what to do with the 5V side scares me a little.  It looks like you're thinking of hooking the USB ground to the "common" tab -- don't do it.  That hooks it to the hot 110V!  The 5 volts is applied across the coil (in this case the two small tabs).  USB 5V to one small tab and USB ground to the other.  

Now for the standard disclaimer.....without seeing the relay, I'm just relying on what's in the picture crashwg has linked....if you see lots of sparks and the relay begins to meld, I must have made a mistake.....

 

[crashwg]

Mwahahahaha, the final piece of the puzzle has arrived today.  

I've already cut off the male end and all I need now is to borrow my homie's multimeter to find out which wires to connect to the relay!

At the rate I get stuff done arround here, I'm pretty sure it should be done sometime this weekend.  

A funny little tidbit:
The cable (only thing I bought) came in a box measuring about 3x5x10"!!!
Seems a little overkill to me...

UPDADE!:

I decided to throw caution into the wind and just go for it.  So I plugged the cable in and touched the wires to my tounge... No seriously, I did.

It fealt like red/black red/green and red/white all had current, so I gave up, but only for a little bit.

I then touched all the different combinations of wires to the relay and the only ones that activated it were the red and black ones... go figure.  I tried them forwards and backwards and both worked so I assume since the relay isn't labeled when it comes to polarity either way will due.

A couple solders later and a little bit of super glue to hold the relay and usb cable in place and it's done, well almost.  I can't seem to find the screws for it so currently it's being held together with rubber bands.  

I've only tried it on my laptop sofar.  Because it has a broken screen of course and it wouldn't be as big of a deal if I fried the USB ports too.  I'm still a little weary of testing it on the main PC of the house mainly because the USB ports are used quite often...  

Overall this has been a satisfying experience.  I didn't realy save myself any money by doing this myself vs. a smart strip, but I do know that it will function properly even when the laptop's battery is charging.  Plus I can say "Check it out dude, this power strip turns on when the computer turns on.  Yea, and I made it myself too dude!"

I'm pretty sure if I look hard enough I can find exactly how much I spent on this but I'm not willing to spend any more time on this project so...

Powerstrip - Wal*Mart - ~$10
Relay - Mouser - ~$6 + shipping ~$4 = ~$10
USB maleB-femaleB cable - pccables.com - $11.16 w/shipping
USB cable - Free, have one already, but...
Lighted USB cable $10 - that'll just make it so much cooler!

So all together I have spent approximatly $30 and plan on spending a tiny bit more.

So there ya go, it works!  Go make one now.

[Dexter]

"because they don't work in the UK"

I think maplin in the UK carry a similar item. Just go to maplin.co.uk and search for "Intelligent Mains Extension Lead"

Dexter

[benwillcox]

OK Guys, I'm thinking about having an autoswitching power strip too, but it seems to me that theres a simpler, cheaper, neater way to do this ....

All you need to do is convert the monitor passthrough power connector on the PSU to switch on only when the computer is powered - then just plug the powerstrip into the monitor passthru.

Basic mod would be the same, but you can put the relay inside the PSU switching the supply to the outlet, and just tap off the 5V or 12V for the relay coil from directly inside the PSU. That way you don't need any USB cables hanging out of powerstrips etc. Safer too, I reckon.

Ben.

[crashwg]

I haven't seen a power supply with a monitor pass thru outlet in a long while...

Not that I've been looking or anything.  I'm just saying, it may be hard to find a power supply like that.

[benwillcox]

I haven't seen a power supply with a monitor pass thru outlet in a long while...

Ah maybe it's a US difference then - over here in the UK it's pretty much the other way round, most of the PSU's have a monitor passthru...

Cheers,
Ben.