Constant current load for testing power supplies (guidelines)

[Th3_uN1Qu3]

Re: Constant current load for testing power supplies (guidelines)

I have a MOSFET load schematic i designed a few years back but never got around to building, i can share if you wish. It has only been simulated but it is such a basic circuit that it is guaranteed to work. It's based on the standard opamp + voltage reference + current shunt topology.

[Dannyx]

Re: Constant current load for testing power supplies (guidelines)

Yeah that would be interesting. That was the original point of this post: for people to come up with their own ideas and designs revolving around the main topic, since I'm sure there are various ways of achieving it, so perhaps in the end we'll combine all those ideas and end up with something that's both functional and revolutionary

[budm]

Re: Constant current load for testing power supplies (guidelines)

http://www.linear.com/solutions/1845

[sam_sam_sam]

Re: Constant current load for testing power supplies (guidelines)

budm
This was interesting but what it lacks is what mosfet or transistors was used
Do you have any clue what was used

[Dannyx]

Re: Constant current load for testing power supplies (guidelines)

Also, stupid question, but why so many resistors in series there ? 470mOhms times 4

[Dannyx]

Re: Constant current load for testing power supplies (guidelines)

Has anyone else been messing around with this project ?

[eccerr0r]

Re: Constant current load for testing power supplies (guidelines)

Selfish answer: no, because I don't see any real use for it on my bench... The way I see it, a PSU needs to be able to deal with constantly varying loads, sometimes even in the kilohertz range. Since I don't need to accurately measure the limits of a PSU - just loading it down with light bulbs is sufficient to get a rough estimate of its capabilities.

BTW, that linear.com sample idea for design, I would assume that:

1. They used 4x470mΩ because you can now get 4x the wattage compared to one individual resistor of the size. Likely the smaller resistors are cheaper.
2. Those transistors are probably not critical. Probably something like IRF520 will do.

[gabiz_ro]

Re: Constant current load for testing power supplies (guidelines)

budm
This was interesting but what it lacks is what mosfet or transistors was used
Do you have any clue what was used

http://www.linear.com/solutions/1845

You ask about that?

Is on photo of schematic
Q1 Q2 2N3904
Q3 Q4 FQA140N10

[budm]

Re: Constant current load for testing power supplies (guidelines)

Sch PDF, provided by Analog Devices.