DIY "smart power strip" for $4.50 (repost)

[spystyle]

Hello from Maine

Hey I figured out how to make a "smart strip" for a mere $4.50 USD

(If you don't know what a smart strip is, it's a power strip that is nice as it (potentially) "turns everything on" when you turn on your computer. So when you press your computer's power button, the computer, monitor, speakers, and accessories all power on at once.)

I discussed this in a long thread in the "everything else" forum, but I thought some might find it useful here.

Here it is :

OK, I figured out how to make a "smart strip" for like $4.50 Ultra-cheap.

This one is 5v so it can connect to 5v molex (from the computer's power supply).

You'd think it could connect to USB (which is also 5v), but I found that USB is "always hot" (at least in the computers I checked). In other words, the USB is constantly outputting 5 volts when the computer is plugged in, regardless if the computer is on or off.

This relay "SRD-5VDC-SL-C" can be had $3.99 for 5 (79 cents each)

(if you don't know what a relay is, a relay is an "on off" switch. In this case when the 5 volts is present it's "on", when it is not present it's "off")

http://www.ebay.com/sch/i.html?_nkw=%22SRD-5VDC-SL-C%22+%225+pcs%22&_sacat=0&_odkw=SRD-5VDC-SL-C&LH_BIN=1&_sop=15&_osacat=0&_from=R40

And this power strip from Walmart "pps1060r/17". It cost only $3.27 and has a 15 amp breaker, so it doesn't seem to be missing anything.

http://www.walmart.com/ip/Philips-Power-Sentry-6-Outlet-Cord-Strip-2.5/21109368

Here is a pic of the price from my local walmart (Auburn Maine) :



So, $3.27, 20 cents tax, 79 cents for the relay =  $4.26 ultra cheap "smart strip"

Pretty funny huh ? I consider a sub-five-dollar "smart strip" to be a milestone in thrifty-hacking

Here are pics of the hack, it's pretty tight and I don't lose the use of any outlets :













(In case you don't understand the process of hacking a power strip, the following pic really explains it all - you simply need to interrupt the "black wire's metal strip". Just a small gap in this "strip" is all it takes. This allows you to have a wire going "out to the switch" on one side, and "in from the switch" on the other side. Now the switch controls whether that "black wire's metal strip" is a connected or interrupted)

(See the 2nd to last photo for more explanation)

















Here are pics of a less precise hack where I lose one of the outlets. This one uses a 12v relay called "hjr-3ff-s-z". It's 12v and cost $1.10 each. This hack uses a different power strip and cost like $7.00 total, but that's still sub-ten-dollars.





Here is how it's wired =

1-3 = black
2-5 = PC (12v)
4 = N/A



(In case you still aren't clear on how a hacked power strip works, the next photo really illustrates it - we simply interrupt the "back wire's metal strip" and connect either side to a switch, it's that simple. The additional wires go out to the computer's power supply. Now when the computer is "on" the power strip is "on", when the computer is "off" the power strip is "off".)





This is a nice savings, because the first relays I used cost nearly $10 each. It was this one from Radio Shack :

http://www.radioshack.com/product/index.jsp?productId=2049722

OK, have fun
Craig

p.s. Disclaimer - Electricity can kill you, make sure your power strip is unplugged when you work on it. Also, solder and flux fumes are unhealthy to inhale. Be sure to have good ventilation and / or a respirator when soldering.

[HaRuMaN]

Excellent.  I'm working on a build now and this is perfect timing. 

[spystyle]

Thanks for chiming in, I'm actually a big fan of your work LOL

[CoryBee]

I actually have a few of these relays sitting around on my workbench from a previous project. I am going to build one of these for sure, too simple. Thanks! 

[spystyle]

Cool

Let us know how it goes.

[MTPPC]

I might recommend a diode across the coil to eliminate any feedback or buzzing problems.

[matt4949]

Ain't this a crock. I could totally build this. I understand the principals behind it. I understand how relays work. I am great at soldering and last night I ordered a $27.00 smart strip off of Amazon.

http://forum.arcadecontrols.com/Smileys/default/banghead.gif

[DaOld Man]

Good writeup spystyle, however I agree with MTPPC, it might be best to add a diode across the coil terminals, but if you do you must observe polarity on the 12 (or 5) volt supply.

[matt4949]

So Your comment about the USB having power whether the computer is off or on got me thinking. Could you add a relay to a power strip that closed when the PC came out of sleep mode? Say your PC was set to sleep after 1 hour of inactivity, when the PC slept it would open the relay shutting off the monitor, lights, amplifier and anything else connected to the strip and when your grabbed a joystick (bringing the PC out of sleep mode) Everything would fire backup?

[CoryBee]

So Your comment about the USB having power whether the computer is off or on got me thinking. Could you add a relay to a power strip that closed when the PC came out of sleep mode? Say your PC was set to sleep after 1 hour of inactivity, when the PC slept it would open the relay shutting off the monitor, lights, amplifier and anything else connected to the strip and when your grabbed a joystick (bringing the PC out of sleep mode) Everything would fire backup?

That should work if your pc doesn't provide power to the USBs during sleep. Software might be able to achieve this? 

[DaOld Man]

You can do some testing if you have an old USB cord, trim it on the end opposite from the plug.
Check power on the black and red wires. You can use a multimeter (5 VDC), or tie it to an led with appropriate resistor for 5 VDC/ (330 ohm should work).
Be careful and do not "short" these wires. It can damage your PC if you do. Also, cut the other two wires (DATA, not red or black) short and do not trim them. Make sure they dont touch anything either.
Also, the frame of the PC is probably the same as the black wire in the usb cable, so dont let the wires touch the PC box.
You can monitor the voltage and do some experimenting.
Please let us know what you find.

[spystyle]

I might recommend a diode across the coil to eliminate any feedback or buzzing problems.

Good writeup spystyle, however I agree with MTPPC, it might be best to add a diode across the coil terminals, but if you do you must observe polarity on the 12 (or 5) volt supply.

What value and what polarity and where ?

I'm not an EE

In fact, I barely understand what I already know LOL

Ain't this a crock. I could totally build this. I understand the principals behind it. I understand how relays work. I am great at soldering and last night I ordered a $27.00 smart strip off of Amazon.

You should dissect and photograph the smart strip so we can see how they did it

It would be hilarious if they were using the same relay

[DaOld Man]

Just about any diode will do. The 1n400 family is good. For your smart strip I would recommend a 1 amp 50 volt (or higher).
Here is a good pick:
http://www.radioshack.com/product/index.jsp?productId=2036270&filterName=Type&filterValue=Diodes

The diode has two leads that would connect to each coil terminal on the relay. (Doesnt matter which lead connects to which terminal).
The diode has a band on one end. This end would connect to the positive of the power supply.
If you reverse the power polarity (negative on the band lead) current would flow through the diode and result in a direct short on the power supply.

[BobA]

I might recommend a diode across the coil to eliminate any feedback or buzzing problems.

What the reverse connected diode does is protect the supply from spikes caused by the coil (inductor) being open circuited when the voltage is removed.  A very good practice for any DC relays.

[spystyle]

Thanks for the tips and information fellas

I swear BYOAC is a place of higher learning !

Can someone illustrate how that diode would go in there ?

[chopperthedog]

 

[spystyle]

Aha thanks!

Now I get it, across the coil with the band pointing towards positive.

[DaOld Man]

Thats right.
But it doesnt have to be right on the relay, if it will give you more room (you want to give the 120 VAC plenty of clearance), you can attach the diode anywhere in the line between the relay and the power supply. Banded end of diode goes on positive wire, the "not-banded end" goes on negative.

Edit:
Hastily botched pic of the pic that you posted:

[spystyle]

Thanks a bunch

[MagicMan]

Nice work

[spystyle]

Thanks, it's a group effort. I had to elicit much help from the EE guys

What would we do without EE guys ?

And of course Saint

[charliepr]

What are the 2 wires that come from the relay for? where do they go??

[chopperthedog]

What are the 2 wires that come from the relay for? where do they go??

Depending upon the type of relay used it goes to either the 5v or 12v feed from the PC power supply. The idea is to have only the PC in the cab connected to a live power feed. All the rest of the items i.e. monitor, sound and lighting are on the relay switched circuit. When PC is powered on voltage is applied to relay to turn on the rest of the items in the cab.


good day.

[RandyT]

I'd use one of these.

No need to worry about diodes or relay contacts, and you wouldn't need to disassemble the power strip.  Easy to mount and connect wires to as well.

[6of1]

I'd use one of these.

No need to worry about diodes or relay contacts, and you wouldn't need to disassemble the power strip.  Easy to mount and connect wires to as well.

Thats what i was thinking.. (correct me if I'm wrong) just a cheap power strip with the hot leg (black) cut and and connected to the AC side and the power(switch) from a PC floppy/molex to the dc side. hardest part would prolly be splicing the power strips cord without destroying it.

was looking to do something just like this for the heated bed on my reprap printer to use a AC heat pad with a DC controller.

[RandyT]

Thats what i was thinking.. (correct me if I'm wrong) just a cheap power strip with the hot leg (black) cut and and connected to the AC side and the power(switch) from a PC floppy/molex to the dc side. hardest part would prolly be splicing the power strips cord without destroying it.

was looking to do something just like this for the heated bed on my reprap printer to use a AC heat pad with a DC controller.

Yes, that's how you would do it.   You could also just buy a cheap outlet box and receptacle (total of a few bucks) and wire it into that.  Then you could just plug in any strip or device as normal.


The only thing which might be a concern on an arcade machine is EM interference on the monitor, but that's something which would have to be determined.

[6of1]

Thats what i was thinking.. (correct me if I'm wrong) just a cheap power strip with the hot leg (black) cut and and connected to the AC side and the power(switch) from a PC floppy/molex to the dc side. hardest part would prolly be splicing the power strips cord without destroying it.

was looking to do something just like this for the heated bed on my reprap printer to use a AC heat pad with a DC controller.

Yes, that's how you would do it.   You could also just buy a cheap outlet box and receptacle (total of a few bucks) and wire it into that.  Then you could just plug in any strip or device as normal.


The only thing which might be a concern on an arcade machine is EM interference on the monitor, but that's something which would have to be determined.

I think It would be safer & easier, but after I posted I realized the spirit of the thread was cost of gettin it done ($4.50 total) not how to get it done. the 25a SSR would be that or more without the power strip or project boxes.. just another option 

[RandyT]

I think It would be safer & easier, but after I posted I realized the spirit of the thread was cost of gettin it done ($4.50 total) not how to get it done. the 25a SSR would be that or more without the power strip or project boxes.. just another option 

No doubt that the way shown is the cheapest way out.  I just wanted to show that for a few bucks more, and still a lot less than smartstrip, there are other ways of doing the same thing which might be easier and/or cleaner.  Also, I wasn't implying the use of a project box, rather a dirt cheap standard outlet box and 110v receptacle available from Wal-mart or any home store.  This would provide 2 switched outlets before a power strip was plugged into it. The same principles apply, and any type of appropriate relay could be used.  If small enough, it can even be taped up and reside inside the outlet box.

[6of1]

project box was a bad choice of words on my part, i knew you meant a single or even dbl gang outlet box.. The extra switched outlet before the strip though would be nice. heavy cord from wall to outlet box/relay then your power strip for PC, monitor etc. the extra outlet could be setup as power for items external of the cabinet (you know like the outlet on the back of your stereo or cable box). I know on top of my "protocab" i have a black light, red spinning light and a strobe to distract people from seeing how god awful my 2x4 mess looks, lol.. I really need to post this ugly thing so people can see just how bad a setup can be, all its missing is duct tape 

[DaOld Man]

On "Stevies Jukebox", here's how I used an external relay on a single "handy box" with a duplex receptacle.
On the receptacle, top outlet is always on, bottom outlet is switched by the externally mounted relay.
This is pretty easy and good way to do it, but the disadvantages to this method is that you only have one switched outlet, so if you need more than one device, you are going to have to use a power strip or "Y" connector. (Or you could use a "dual gang" box and mount another duplex receptacle, then you would have 3 switched outlets.)
Also this method offers no power surge protection, whereas a hacked power strip would, if it was originally designed to be a surge protector. So you would most likely need to use a power strip anyway, just to protect your computer. But it could be external to the cab.

EDIT: I just remembered that both of the outlets are switched. If you look close you will see two cables going into the bottom of the box. One is the power cable and the other is the cable to the PC power supply.
Inside the box, I wired the incoming power and the PC power cables together, and the duplex receptacle is switched on and off by the relay. So this is yet another way to do it.

[Rick]

Yes, that's how you would do it.   You could also just buy a cheap outlet box and receptacle (total of a few bucks) and wire it into that.  Then you could just plug in any strip or device as normal. The only thing which might be a concern on an arcade machine is EM interference on the monitor, but that's something which would have to be determined.

I know I'm resurrecting an old thread, but I don't have the experience to be able to make sense of all this. Could someone possibly give me a hand with some type of rudimentary wiring diagram using these relays? I just bought one from E-Bay to give it a try. It's certainly a better solution than buying more smart strips!

[spystyle]

I can try to help you. Post a link to the relay you bought and I'll take a look

[PL1]

There's a good tutorial on relays here for anyone wanting to understand how they work.   


Scott

[Rick]

I can try to help you. Post a link to the relay you bought and I'll take a look

It's this one, right here. (Exactly the same make and model as the one Randy posted.)

There's a good tutorial on relays here for anyone wanting to understand how they work.   

Thanks! I'll give 'er a read!

[spystyle]

I'm not familiar with that relay, but it looks like the power strip's negative wires goes to the AC side. and the computer's ATX wires (5v or 12v) go to the DC side.

Unlike the little relays that have 5 posts, so you can choose between Normal Open and Normally Closed (we want Normally Open), this one must have a switch, or is just set to Normally Open ()

Edit, Oh here it is at Amazon :
http://www.amazon.com/SSR-25DA-Solid-State-Output-AC24-380V/dp/B00NC5IN0O

It's mentioned in the description that the contacts are "Normally Open". So I guess you don't have to choose between NO and NC. That's handy LOL.

But this relay is relatively expensive. You won't end up with a sub-5-dollar hacked powerstrip LOL.

[Rick]

I'm not super familiar with that relay, but it looks like the power strip's negative wires goes to the AC side. and the computer's ATX wires (5v or 12v) go to the DC side. When the computer is powered on, the relay closes the circuit and turns the power strip on. We skip the first slot on the power strip so it is always on, and the rest is controlled by the relay.

So, if I was to link two additional outlets to it (one for a mini-amp with it's own power supply, and one for the LCD) would this work as I hope? (Or, am I incorrect in how I assume this relay works?)

[spystyle]

So you are not going to hack a power strip like this ?

http://postimg.org/image/62a4diir3/

But you want to wire to an outlet box like this ?

http://forum.arcadecontrols.com/index.php?action=dlattach;topic=128892.0;attach=276225;image

[Rick]

So you are not going to hack a power strip like this?

http://postimg.org/image/62a4diir3/

Bear with me, and please accept my apology... It's been years since High School electronics class, where I briefly remember building a similar circuit. (So, pretend I'm eight, or at least, with little-to-no knowledge of what I'm doing.)



I have read through this thread, and get the gist of what's been said. I have one of the relays that Randy mentioned, but may not have understood why they were recommended as opposed to the smart-strip hack you're mentioning. (They may be better, they may do something completely different - that's what I'm hoping someone can explain.) I'm guessing it's probably the "holy crap, relays do something totally different than what you want, dummy" explanation, but I'm hoping someone can point me in the right direction.

Can the relay I mention be integrated into an inexpensive power bar, to power on secondary items (LCD and amp) when the main PC powers up? If so, can it be wired into the outlets, or (I'm guessing) is it more of a "direct drive 12V output" that is made to bypass other power adapters and such?

(And if I haven't said it yet, or enough - thanks for putting up with a noob question!)

[spystyle]

So you don't want to do it as illustrated in the first post ?

And what is a "power bar" ? LOL

[Rick]

So you don't want to do it as illustrated in the first post?

Don't I? (See, I can be ambiguous too!)



I honestly don't know what I want, but if someone could draw me a picture in MS Paint, showing me how to integrate the relay Randy recommended into a power "strip" (lol), I would be very, very appreciative!

And what is a "power bar"? LOL

Sorry - Canadian here. It's a common reference.