What my question was about was to connect 2 power supplies like you would 2 batteries to provide + and - supplies. I was considering building an analog posative and negative 28V supplies with a 12V 1A PS as a third output. I was looking at in the end a + and _ 24V variable 0.to 5 amp max output. I even have the transformer picked out just need to order it. 120/230V input and the outputs I mentioned 320W was what I was looking at and I thought with 2 channels flat out that would be about 240W for both and the 12V only adds 12W more or maybe 24W more to it if I get a 12V 2A out. I figured 320W should do it. But if I could for now take 2 of my PSU units I have and connect them like batteries that would work for now. but I have been told that this is a good way to destroy a PSU and I don't have a lot to go around. Not going to do dumb things like that. Also I have been looking into what sort of components I would need and Thinking that even if I can build it it is going to cost a lot of money to do it. it would have all I want in a 1 ton PSU but I will never have to move it. It's the beauty of being old.

 

What my question was about was to connect 2 power supplies like you would 2 batteries to provide + and - supplies. I was considering building an analog posative and negative 28V supplies with a 12V 1A PS as a third output. I was looking at in the end a + and _ 24V variable 0.to 5 amp max output. I even have the transformer picked out just need to order it. 120/230V input and the outputs I mentioned 320W was what I was looking at and I thought with 2 channels flat out that would be about 240W for both and the 12V only adds 12W more or maybe 24W more to it if I get a 12V 2A out. I figured 320W should do it. But if I could for now take 2 of my PSU units I have and connect them like batteries that would work for now. but I have been told that this is a good way to destroy a PSU and I don't have a lot to go around. Not going to do dumb things like that. Also I have been looking into what sort of components I would need and Thinking that even if I can build it it is going to cost a lot of money to do it. it would have all I want in a 1 ton PSU but I will never have to move it. It's the beauty of being old.

You can do this but you need to fully understand how they might be grounded and if they are isolated and so on.

If the -ve leads of the PSU's are somehow connected to ground then when you connect the +ve of one to the -ve of the other you'll short circuit that PSU. If two PSU's each have their -ve tied to ground, then effectively each PSU's -ve is connected together.

For example I believe the -ve rail on a PC (which are switch mode) power supply is tied to ground, so you could never string two of them in series.

 

Just make sure that the power supplies are floating.
If you are trying to tie two power supplies in series, at least the one further away from ground must be floating. If both are grounded then you are creating a short circuit on the lower one.

 

Assuming neither power supply has its negative lead connected to Ground. (must be floating)
I drew batteries because I don't have a picture of power supplies.
I often series power supplies. If you short out the supplies by mistake the supplies might fight each other. Bad things can happen. I place a diode across each supply all the time. If V+ gets shorted to V- it is likely one supply will push current backwards through its brother. The diodes keep the supplies from getting more than -0.8V across the supply under these conditions.

 

You can do this but you need to fully understand how they might be grounded and if they are isolated and so on.

If the -ve leads of the PSU's are somehow connected to ground then when you connect the +ve of one to the -ve of the other you'll short circuit that PSU. If two PSU's each have their -ve tied to ground, then effectively each PSU's -ve is connected together.

For example I believe the -ve rail on a PC (which are switch mode) power supply is tied to ground, so you could never string two of them in series.

Yea so that's what I thought. I'm not into destroying power supplies. So it sort of looks like the analog rout is the only way to go to get what I want. it's going to take some time to build that. Nipon Chemicon filter caps for sure and probably throughout the power supplies. some very good fans and huge heat sinks. She will get hot.

 

Assuming neither power supply has its negative lead connected to Ground. (must be floating)
I drew batteries because I don't have a picture of power supplies.
I often series power supplies. If you short out the supplies by mistake the supplies might fight each other. Bad things can happen. I place a diode across each supply all the time. If V+ gets shorted to V- it is likely one supply will push current backwards through its brother. The diodes keep the supplies from getting more than -0.8V across the supply under these conditions.
View attachment 368830

Yea that's taking maybe to dangerous a direction and it's sort of cheating the systems and it could still to damage and that is not in the cards. I only have 3 PSU's and only 2 of them may be what I need but still I don't think I'll risk that. It's going to suck up money like crazy to build what I want but the end result will be all I ever wanted in a PSU even if I need a fork lift to move it.

 

You can do this but you need to fully understand how they might be grounded and if they are isolated and so on.

If the -ve leads of the PSU's are somehow connected to ground then when you connect the +ve of one to the -ve of the other you'll short circuit that PSU. If two PSU's each have their -ve tied to ground, then effectively each PSU's -ve is connected together.

For example I believe the -ve rail on a PC (which are switch mode) power supply is tied to ground, so you could never string two of them in series.

No but a PC power supply does have a fixed 12 -12 and a fixed 5 -5 supply all it would seem on the same switching power supply. but as hard as I try I can not for the life of me find a 24-0-24 power supply of the switching variety. But I am able to custom order a toroidal transformer with a 28-0-28 and a 12V 1 or 2 Amp at a reasonable price given I'm asking for 320W total.

 

But I am able to custom order a toroidal transformer with a 28-0-28 and a 12V 1 or 2 Amp at a reasonable price given I'm asking for 320W total.

What's a reasonable price, and where from?

 

What's a reasonable price, and where from?

Well obviously it's from China but it was recommended to me as being very good at what they do. All they do is make toroidal transformers and the engineer that recommended it to me has ordered several. and reasonable is a bit over 200.00. I am asking for a lot but not out of line for them they will do 500+ Wats mine is 320

 

Well obviously it's from China but it was recommended to me as being very good at what they do.

Link?

 

Link?

You can find them the same way I was told to do it. go on aliexpress yes that aliexpress. when you get there type in the following prompt. custom toroidal transformer. they are I think the third one in the list. the only one that states they do custom transformers even one off transformers. They will even help you through the process of getting just the right one for your needs. but the thing I am finding out is that getting the transformer is only 1/10'th of the battle. So much more will be spent one all the components to make it work for you. If like me you want nothing but the best in those components. the price of the transformer hardly makes a dent.

 

You can find them the same way I was told to do it.

Nope. That's not how this works. Among other things, the idea that search engines on different computers in different countries will return the exact same list in the exact same order is . . . incorrect.

There could be dozens of transformers to choose from, and we don't have nearly enough information to *guess* which one you settled on. The only way we can discuss the unit you have is for you to give us a link to the exact unit you have.

ak

 

Nope. That's not how this works. Among other things, the idea that searches from different computers in different countries will return the exact same list in the exact same order is . . . incorrect.

There could be dozens of transformers to choose from, and we don't have nearly enough information to *guess* which one you settled on. The only way we can discuss the unit you have is for you to give us a link to the exact unit you have.

ak

There isn't because I was only able to find one when I did that search that specifically stated they do custom and one off transformers. 15 years experience. No others offer that.

 

I was looking at in the end a + and _ 24V variable 0.to 5 amp max output.

https://www.aliexpress.us/item/3256...5008077593498|_p_origin_prod:1005008617922037

 

Yea that's taking maybe to dangerous a direction and it's sort of cheating the systems and it could still to damage and that is not in the cards.

Hardly dangerous – it just requires verifying that the power supply outputs aren't connected to input power ground.

 

https://www.aliexpress.us/item/3256807891278746.html?spm=a2g0o.productlist.main.2.1335Ws3DWs3D8D&algo_pvid=acf04994-8f72-46b2-a863-c268544949b6&algo_exp_id=acf04994-8f72-46b2-a863-c268544949b6-1&pdp_ext_f={"order":"1274","eval":"1","orig_sl_item_id":"1005008077593498","orig_item_id":"1005008617922037","fromPage":"search"}&pdp_npi=6@dis!USD!39.63!19.02!!!268.32!128.79!@21033d1217827448058351806efa6c!12000043565613673!sea!US!0!ABX!1!0!n_tag:-29910;d:d58e1e92;m03_new_user:-29895&curPageLogUid=3GOajhuvU8tZ&utparam-url=scene:search|query_from:|x_object_id:1005008077593498|_p_origin_prod:1005008617922037
View attachment 368852

Those would probably do the trick for me. And it would keep the weight down to something less than forklift weight. And it's cheaper and probably much more efficient. I guess I will have to work something else out for the smaller "sort of" projects also going in the case. they take 12V @ < 1A maybe 3 or 4A with one of them. I think since I would not really be running the power supplies at the same time I could split off the + line and make a 12V out of that for the other projects. It will be the power supply that has everything I ever wanted in a decent power supply. It will still require a large case. Good thing I have a friend that has a 3D printer business and he is willing to print the box for me but I have to buy the plastic rolls he will use for it. Sounds like a deal to me. another problem taken care of. only 300 to go.

 

Those would probably do the trick for me. And it would keep the weight down to something less than forklift weight. And it's cheaper and probably much more efficient. I guess I will have to work something else out for the smaller "sort of" projects also going in the case. they take 12V @ < 1A maybe 3 or 4A with one of them.

Instead of buying fixed voltages, I'd buy 2 variable power supplies that could be connected in series to make +/-24V.

Two of these would give you higher voltages and higher current:

Note the order of the supply terminals. This one doesn't have earth ground (which suites me just fine). I have 3 of the 0-30V at 6A.

This one has the output terminals in a screwy order:


This one has them in the more logical order:

Earth ground should be on the outside so you can use a 2-terminal banana jack to connect the supply.

Wanptek Adjustable DC Power Supply 30V 10A LED Lab Bench Power Source Stabilized Switch Power Supply Voltage Regulator 60V 5A
Note that these supplies are all from the same company...


I'd skip the gold plated contacts.

 

Be careful of other screwy supply terminals.

This Velleman doesn't use the standard order or spacing and it uses the "safety" banana jacks instead of 5-way banana jacks:

My fix:

I didn't use 5-way banana jacks because they were too long.

 

Instead of buying fixed voltages, I'd buy 2 variable power supplies that could be connected in series to make +/-24V.

Two of these would give you higher voltages and higher current:
View attachment 368854
Note the order of the supply terminals. This one doesn't have earth ground (which suites me just fine). I have 3 of the 0-32V at 6A.

This one has the output terminals in a screwy order:
View attachment 368855

This one has them in the more logical order:
View attachment 368857
Earth ground should be on the outside so you can use a 2-terminal banana jack to connect the supply.

Wanptek Adjustable DC Power Supply 30V 10A LED Lab Bench Power Source Stabilized Switch Power Supply Voltage Regulator 60V 5A
Note that these supplies are all from the same company...

View attachment 368856
I'd skip the gold plated contacts.

I realize that I already have several power supplies. what I was needing was the negative portion of the power. I needed 24-0-24 at least at about 320 to 350W. I was told about a switching power supply that has specs like that. probably what I will go with.

 

I realize that I already have several power supplies. what I was needing was the negative portion of the power.

You can connect supplies in series if the outputs are floating.