need 18 volt 10 ampere dc output circuit

[tanveer habib]

Hello all, i need 0 to 18 volt variable dc voltage and 0 to 10 ampere current .

can any one provide a circuit for it how to design it and what transformer spec should i use.

 

[Ramussons]

How about using a couple of Computer PSU units to get the 18 volts? 5 + 12 with a little tweaking should do the job.

 

[tanveer habib]

How about using a couple of Computer PSU units to get the 18 volts? 5 + 12 with a little tweaking should do the job.

yes that sounds promising but how much ampere will i get at 12 volt output I need 10amp

 

[Cicero]

What kind of application is this for?

Do you need variable current limiting?

A completely variable PSU up to those limits is not a simple task, 180W. If its for a bench power supply, I'd simply buy one.

 

[tanveer habib]

What kind of application is this for?

Do you need variable current limiting?

A completely variable PSU up to those limits is not a simple task, 180W. If its for a bench power supply, I'd simply buy one.

yes i need variable current limiting

 

[AnalogKid]

The easiest to build from scratch is a standard linear regulator, BUT -

the transformer will weigh at least 5 pounds
the transformer will cost over $50.00
the regulator will need a fan
The filter capacitors will be large and expensive

https://www.digikey.com/products/en...olumnSort=1000011&page=1&stock=1&pageSize=500

Have you done anything like this before? What is your skill set for building this device? You can search for lab power supply or bench power supply schematics to see the kinds of circuits used.

ak

 

[Cicero]

Yip, its expensive to make yourself.

I'm gonna step off, and just leave this here:
**broken link removed**

EDIT: Oh, from OP's other threads it seems this is for some sort of commercial application for battery charging. So a bench supply isn't helpful in this case...unless you buy and copy one.

 

[unclejed613]

How about using a couple of Computer PSU units to get the 18 volts? 5 + 12 with a little tweaking should do the job.

that might not work. the grounds will tie together at the wall outlet.

 

[AnalogKid]

How about using a couple of Computer PSU units to get the 18 volts? 5 + 12 with a little tweaking should do the job.

In an ATX power supply, the +5 V and +12 V outputs share a common ground. They cannot be added.

ak

 

[Ramussons]

Post #8 and Post #9. I said use a couple of PSU units. You can make the outputs floating and add them up.

 

[Ramussons]

yes that sounds promising but how much ampere will i get at 12 volt output I need 10amp

You'll get well above the 10 A required, but a current control will require some bit of playing around.

 

[AnalogKid]

Post #8 and Post #9. I said use a couple of PSU units. You can make the outputs floating and add them up.

I missed that (or read it as a couple of PSU outputs). Point to you.

Note, the combined output will have poor regulation and noise performance, both outside the ATX spec. Also, there is a chance that one or both outputs will oscillate under some load conditions as the two control loops get into a fight.

ak

 

[Externet]

Smells like a battery charger/starter booster type could do it.

 

[Ramussons]

I missed that (or read it as a couple of PSU outputs). Point to you.

Note, the combined output will have poor regulation and noise performance, both outside the ATX spec. Also, there is a chance that one or both outputs will oscillate under some load conditions as the two control loops get into a fight.

ak

Yes. That's a possibility. Did'nt strike me

 

[AnalogKid]

I have stacked up (outputs connected in serial) commercial, medical, and MIL power supplies. I always got them to work, but it usually was an effort. Noise always was an issue, and systems with remote sense were tricky.

ak