15 V at 1 Amp DC Negative Polarity Power Supply

[Tempest]

I need a barrel tip power supply that is 15 V at 1 Amp DC and with the outside sleeve of the plug positive and the inside tip negative (negative polarity).

[CPUWIZ]

Buy a standard one, cut it in half, solder back together in reverse, put some heatshrink tubing on it and plug it in.

 

Also, barrel sizes differ.

[Bratwurst]

I prefer to open the power pack housing to reverse the wiring, myself, when it's possible.

 

What's this for?

[CPUWIZ]

I prefer to open the power pack housing to reverse the wiring, myself, when it's possible.

 

What's this for?

 

Most of them are solid blocks, do you have a trick?

[Tempest]

I prefer to open the power pack housing to reverse the wiring, myself, when it's possible.

 

What's this for?

A Timex TS2064. I dont know the barrel size yet Im afraid. I have a few spare power supplies around here but theyre all 12V. 15V seems uncommon.

[Bratwurst]

I am sure I have a 15V in my box of spares. Keep me updated on the tip size you need (inner and outer diameter) and I will see what I can do for you.

 

 

Most of them are solid blocks, do you have a trick?

 

The mini extendable/breakaway utility knives are good for slipping into seams because they are thin, and a blast of hot air gun on low will weaken glue. It can vary and does take practice. I'll see about taking pictures when I try opening my Jaguar supply because it needs a new cord, insulation is broken right at the strain relief on one conductor. If I break the housing I'll just put it in a new one, preferably one with screws.

 

I used to open car computer modules and they are much scarier, stamped/pressed aluminum with silicone adhesive spread between the PCB and metal plates.

[Tempest]

Sure. Im pretty sure its the standard size that most systems use (it came with a generic power supply), but Ill double check.

[Bratwurst]

Looking at an eBay listing for a Timex TS2068 it comes with a power pack that looks like a standard 5.5mm OD 2.1mm ID tip so it is probably similar. This is a good reference:

Measuring Power Supply Barrel Plug ID 2.1mm vs 2.5mm

I just checked. I have two 15V .9A and one 18V 1A supplies. Not sure how much amperage your Timex actually needs.

[Osgeld]

I will check when I get home from work, I think I have one with the tip cut off, and I bag of solder on tips

[Tempest]

Looking at an eBay listing for a Timex TS2068 it comes with a power pack that looks like a standard 5.5mm OD 2.1mm ID tip so it is probably similar. This is a good reference:

Measuring Power Supply Barrel Plug ID 2.1mm vs 2.5mm

I just checked. I have two 15V .9A and one 18V 1A supplies.

What's 100ma between friends?

[Bratwurst]

Probably not a big deal. But if Osgeld has a 1 amp supply go with that. If not PM me when you figure out the tip size.

[Osgeld]

the one I have is 15 volt 3 amp, its a little power brick for a netbook I no longer have

[Tempest]

the one I have is 15 volt 3 amp, its a little power brick for a netbook I no longer have

 

I would think that 2 extra amps would be worse than .1 fewer amps, but I'm not sure.

[Osgeld]

well its got regulated voltage output so if whatever is plugged into it is not using close to the full current it doesnt matter (unlike a magnetic type where you have to have somewhere around 70% load for the voltage to fall into spec)

 

either way I think you would be fine

 

edit:

quick glance at the schematic its got a cute little power supply in the computer, but its still got a 7812 to provide 12 volts so which is only good for 1 amp max if it doesnt overheat first. Current ratings on supplies are just how much they can possibly provide, and with old transformer based units you want to stick close. With new regulated switch mode power supplies you can have more than you need and the voltage output wont float high.

 

The thing though is if you got a circuit that fails, its going to be a heck of a lot more dramatic since its got 3x the potential force behind it heh (you are still screwed either way in that case)

Edited April 8, 2018 by Osgeld

[Bratwurst]

Osgeld's correct, the extra amperage in this instance would not hurt.

[Tempest]

So let me see if I understand this correctly. You're saying that since it's a newer power supply that the extra amperage is ok because power supplies these days regulate it better, but if it was an older power supply it would probably not be ok?

 

I'll defer to your judgement on this one as to which is better way to go.

[Osgeld]

Yes new switch mode regulated power supplies will pit out a constant voltage regardless of load

 

Old transformer types need to have a percentage of its rated load to fall into spec (ie this is why a 9v power supply for an atari measures like 14 when the system is unplugged or off but pretty close to 9 when on)

[Tempest]

Ok then, sold! I'll shoot you a PM. Thanks!

[Tempest]

I got the power supply today, but it doesn't fit! The plug appears to be too big.

[CPUWIZ]

I got the power supply today, but it doesn't fit! The plug appears to be too big.

 

What did I tell about barrel size?

[Tempest]

It *looks* like a standard sized plug but it must be slightly larger or smaller. I can try and get an accurate measurement next week but Im not good at such things.

[Osgeld]

I got a multiplug adapter kit for 50 cents at a thrift store thinking "hell I will use that" and I have not used it in 2 years so I will mail that off hopefully one of them will fit right