Very Basic Power supply questions.

Post by **vickyg2003** » Fri Jun 16, 2017 7:22 pm

1) I got an HDMI switch that is powered by USB, but no adapter came with it. The documentation says it needs a 5v 1.5 amp power supply. I have a Monster Power surge protetorp that has two USB ports. One is labeled phone the other labeled tablet. I can't find any documentation on these ports. Would one of these USB ports be safe to use with my switch?

2) I've got an old battery operated Pac-Man game that you plug into a TV. It takes 4 AA batteries. The batteries are always dead when we want to use it. How would I go about changing this to use an external power supply?

Post by **The Robman** » Fri Jun 16, 2017 7:26 pm

1) You could try it and see. If the switch uses USB power and they didn't provide a power supply, I have to imagine that most regular USB power supplies would work (ie, the kind that you use with phones, etc).

2) 4 AA batteries give 6v, so all you need to do is find a 6v AC adapter and then rip off the plug at the end and solder the wires to the + and - battery terminals in the game.

Post by **vickyg2003** » Fri Jun 16, 2017 7:48 pm

The Robman wrote:
2) 4 AA batteries give 6v, so all you need to do is find a 6v AC adapter and then rip off the plug at the end and solder the wires to the + and - battery terminals in the game.

I looked through my chargers, and I have one that says 5.8V 130mA. I cut the end off it. It didn't have wires like a lamp, where you can see two distinct wires, it looked like one wire. When I cut off the end one of the wires is sheathed in white plastic, the other one is bare. Can I use this? And if so which one is the -? And the wires are twisted around a fiber, is this going to be a problem with soldering?

Will this pose any danger? This is used by small children and saftey first!

Post by **The Robman** » Fri Jun 16, 2017 8:17 pm

Do you have a multimeter? If so, use that to test the wires to see which is + and which is -.

As for safety, I would drill a small hole in the battery door (or anywhere else that you think might work), just big enough for the wire to go through, then tie a knot in the end of the wire after it has been fed through so it can't be pulled back.

Post by **vickyg2003** » Fri Jun 16, 2017 8:56 pm

My DH has something that looks like a it might be a multimeter in the garage. I set it to 2v and tested a battery. I think my charger might be proprietary so I'm just going to get one that is generic and has 2 wires coming out. I'll get back to you on the where to solder when it arrives.

Post by **vickyg2003** » Fri Jun 16, 2017 9:06 pm

This looks cool.

http://www.wikihow.com/Make-Battery-Eliminators

Post by **The Robman** » Sat Jun 17, 2017 9:09 am

If you want to avoid modifying the Pacman game itself, that would be the way to go.

I had someone with a similar request here several years ago, it was a guy who wanted to use Timed Macros on a Producer 8 to switch something on the TV in his bar, so basically he wanted to leave the remote in one place forever and have it keep changing channels or something, so needless to say, he wanted to plug it in rather than have it use batteries, so I had him do the same thing, hack an AC adapter and solder the wires into place, which he did and it worked.

Post by **The Robman** » Sat Jun 17, 2017 9:15 am

As for the multimeter, this is what a typical "analog" and "digital" multimeter look like, they let you switch between measuring resistance, AC voltage or DC voltage, and maybe capacitance:

Post by **vickyg2003** » Sat Jun 17, 2017 1:58 pm

This is the thing I found in the garage that I thought was a multimeter. No idea how to use this thing and electricity scares me.

This is the charger that I cut the end off. There is a little diagram that probably tells me which one is positive and which is negative.

Post by **The Robman** » Sat Jun 17, 2017 2:34 pm

If you turn the dial to about the 2 o'clock position, you will be in 20v DC range, then put the red lead on what you think is the positive wire and the black lead on the negative wire, and you should see 5 or 6 volts on the screen. If you get it backwards, you might see a negative number.

I've never used a digital multimeter, so I'm guessing about the screen readouts, with my analog meter, if I get it backwards, the needle tries to go below zero.

Don't let 6v electricity scare you, lol.

pH7_jp1 · Post by **pH7_jp1** » Sat Jun 17, 2017 5:12 pm

Yes, the little diagram is saying that the wire in the center is negative and that the outer sheath is positive. If you are lucky the switch will have a similar diagram that shows what it needs, so you know how to connect to the plug.

Post by **The Robman** » Sat Jun 17, 2017 7:17 pm

The diagram actually describes how the original plug (ie, the one she removed) was configured (ie, it had a negative tip). I don't know if that means the wire was also configured that way. I have some adapters that have a plug in the middle of the wire which allows you to switch the tip between negative and positive.

Post by **vickyg2003** » Sun Jun 18, 2017 8:31 am

The Robman wrote: Don't let 6v electricity scare you, lol.

But its plugged into the wall!!!

Phil wrote:If you are lucky the switch will have a similar diagram that shows what it needs, so you know how to connect to the plug.

Hadn't taken that into consideration. I have no practical knowledge on this, I was playing arcade games when I should have been taking apart electronics.

I guess the batteries complete the circuit the + of one end to the - at the other one, so I need to know which way this flows. So I need to figure out which + and which - to use in the battery compartment so I can complete the circuit without the batteries.

This really does illustrate that I am not a hardware person. I'm into this hobby to keep the remote-clutter off the coffee table!

Post by **The Robman** » Sun Jun 18, 2017 9:25 am

I think Phil was getting your 2 separate requests mixed up. If I understand your original post correctly, you are trying to power 2 separate devices.

First you have a switch that uses a USB connection for power, so that one you can power with a regular USB cable and a power brick, so no need to worry about +/- polarity there.

Second, you have an old Pacman game that only runs on 4 AA batteries, and as each battery gives 1.5v, you're looking at a total of 6v approximately. The flat end of batteries is the negative end and the end with a little button shape is the positive end, or to put in terms of the terminals in the game, the end with the spring is the negative end and the flat end is positive. As there are 4 batteries, I assume you line them up in a 2*2 pattern, so one end will simply be a pass-thru connector, the other end will have separate connectors that actually carry the power into the device. That is the end where you would solder your wires.

And even though the AC adapter plugs into the wall, the power coming out of the wires is the same as what the 4 batteries would give you, so if you're not afraid to handle the batteries, don't worry too much about the adapter.

Post by **vickyg2003** » Sun Jun 18, 2017 10:53 am

The Robman wrote:I think Phil was getting your 2 separate requests mixed up. If I understand your original post correctly, you are trying to power 2 separate devices.

You do

First you have a switch that uses a USB connection for power, so that one you can power with a regular USB cable and a power brick, so no need to worry about +/- polarity there.

Yes, we decided since I don't have a USB power brick, I'd plug it into the USB slot labeled "phone" on my surge protector.

Second, you have an old Pacman game that only runs on 4 AA batteries, and as each battery gives 1.5v, you're looking at a total of 6v approximately. The flat end of batteries is the negative end and the end with a little button shape is the positive end, or to put in terms of the terminals in the game, the end with the spring is the negative end and the flat end is positive. As there are 4 batteries, I assume you line them up in a 2*2 pattern, so one end will simply be a pass-thru connector, the other end will have separate connectors that actually carry the power into the device. That is the end where you would solder your wires.

We are talking about doing this from the battery comartment and not tring to open the box, correct? I'm still a little fuzzy here, but I now think I can do it, if nothing else I can use the dowel method. That one I get. I've been looking at how other people put together there arcade games, looking for something that looks good. I did learn how to use power tools when they decided that the girls in our school would be required to take shop. I just wish they had been that open minded about letting the girls take physics instead of biology!

And even though the AC adapter plugs into the wall, the power coming out of the wires is the same as what the 4 batteries would give you, so if you're not afraid to handle the batteries, don't worry too much about the adapter.

Good to know as I was terrified of touching it with that multi-meter.