How to make your own ColecoVision Power Supply that operates worldwide

[MrPix]

Google ‘sarcasm’ ?

[towmater]

I just saw an auction for a colecovision, and the pictured power supply was clearly for a TI-99. Are they compatible? I'm asking because you look to be the power supply expert.

 

[HDTV1080P]

6 hours ago, towmater said:

I just saw an auction for a colecovision, and the pictured power supply was clearly for a TI-99. Are they compatible? I'm asking because you look to be the power supply expert.

 

The answer is no. The ColecoVision power supply outputs DC voltage at 12 volts DC, 5 volts DC, and -5 volts DC. The TI/99 power supply outputs AC voltage at 16 volts AC and 8 volts AC.  The connector will fit but the TI-99 power supply would most likely fry the ColecoVision videogame system.

Edited June 7, 2020 by HDTV1080P

[Tursi]

18 hours ago, HDTV1080P said:

The answer is no. The ColecoVision power supply outputs DC voltage at 12 volts DC, 5 volts DC, and -5 volts DC. The TI/99 power supply outputs AC voltage at 16 volts AC and 8 volts AC.  The connector will fit but the TI-99 power supply would most likely fry the ColecoVision videogame system.

And if they are pictured together... probably already has...

 

[Junior96]

I realize this is an old thread but i just wanted to mention that for anyone wanting to go the computer PSU route, you don't really need a PSU that supplies a -5vdc, you can use the +5vdc you just switch the leads believe it or not, put your meter on it to see for yourself, there are like 30 configurations that can be derived from a modern ATX power supply by manipulating the voltages ex: +12vdc and -5vdc in series would give you 7vdc. using the center and the positive 12. Now if you have no idea what im talking about then you probably have no business playing with electricity anyway...Im going straight to the board as i dont have any of the power cord for the CV. I may design my own usb or not, but the computer PSu can be used for almost any configuration you need and I feel they are the best bang for the buck.

 

Just thought id toss this out there, i just have a hard time spending the $50.00-$60.00 people are charging for the power supplies, and i know about the usb one, but im an electrical engineer and that would be like a chef going and ordering a burger from Mcdonalds...lol 

[nick3092]

I am not an EE, but I'm fairly certain swapping 5v leads will not work in this case to get you a usable -5v. The ram chips are going to want that -5v in reference to the ground pin on the chip. And that ground pin has to be common to all voltages going in to the chip. If the chip had a separate ground pin for -5, this might work. But since it's common to +5 and +12 as well, I don't see how that will work. 

[Tursi]

15 minutes ago, nick3092 said:

I am not an EE, but I'm fairly certain swapping 5v leads will not work in this case to get you a usable -5v. The ram chips are going to want that -5v in reference to the ground pin on the chip. And that ground pin has to be common to all voltages going in to the chip. If the chip had a separate ground pin for -5, this might work. But since it's common to +5 and +12 as well, I don't see how that will work. 

Well, going from -5 to +12 also gives you 17v, not 7v, but that's okay. Possibly he's just wording it poorly, possibly it's the internet.

 

 

[+5-11under]

If all the supplies are isolated, you can do the addition and subtraction/reversals. For example with a 9V and 1.5V battery you can get + or - 7.5V or + or - 10.5V, depending on how you connect them. If they're not isolated from each other, something bad will happen. Don't try it unless you're absolutely sure. As mentioned, you can find bricks or supplies that provide the correct voltages with sufficient current.

[Tursi]

2 hours ago, 5-11under said:

If all the supplies are isolated, you can do the addition and subtraction/reversals. For example with a 9V and 1.5V battery you can get + or - 7.5V or + or - 10.5V, depending on how you connect them. If they're not isolated from each other, something bad will happen. Don't try it unless you're absolutely sure. As mentioned, you can find bricks or supplies that provide the correct voltages with sufficient current.

Can you offer up some links to read more about that? I wasn't aware it was possible to reduce the overall voltage with a series connection...

 

[+5-11under]

15 minutes ago, Tursi said:

Can you offer up some links to read more about that? I wasn't aware it was possible to reduce the overall voltage with a series connection...

 

I didn't really have a link in mind.

Really, the battery example works well, because the sources are isolated, without any common ground/connection. I just tried it, to make sure.

That said, I haven't really thought about how it works in real life if you're trying to get 7.5V from the 9V and 1.5V battery, like how the batteries would drain.

 

But, for the given example of a ColecoVision, if you have a 12V battery and a 5V battery, and if you connect the + of the 5 to the - of the 12, and call that your ground point, then the - of the 5 is -5V, and the + of the 12 is +12V (both relative to the ground point).

[Tursi]

6 hours ago, 5-11under said:

I didn't really have a link in mind.

Really, the battery example works well, because the sources are isolated, without any common ground/connection. I just tried it, to make sure.

That said, I haven't really thought about how it works in real life if you're trying to get 7.5V from the 9V and 1.5V battery, like how the batteries would drain.

 

But, for the given example of a ColecoVision, if you have a 12V battery and a 5V battery, and if you connect the + of the 5 to the - of the 12, and call that your ground point, then the - of the 5 is -5V, and the + of the 12 is +12V (both relative to the ground point).

Yes, but that gives you -5 and +12 and is a common way of getting a negative voltage - it's not what I was questioning. It's okay to do that, because you're still pulling from each power source individually and just creating a common reference. "Ground" is nothing magic, it's just the 0v reference point of the circuit. Likewise, the "+" of the 5 is only +5 relative to it's negative terminal, on it's own it's nothing. That's why that works.

 

That means, if you try to pull from the -5 to the +12 in that arrangement, you will get 17v pushed through both batteries! And while it'll work for a while, it'll eventually destroy one or both of them as they won't discharge evenly.

 

What I'm confused about is this claim of getting 7.5v from a 9v and 1.5v. I can't find anything online that says how you'd wire that, and I'm curious. If you don't have a link that explains the theory, how about a quick schematic so I can try it too?