If your concern is matching Vgs and Gm, you can use such a thing:Hi All,
Trying to match a few p channel fets and wanted to make a simple circuit to match them.
Has anyone got a link please to a good circuit, I seem to only find n channel fet matchers?
Do you have the regular model or the Pro?Question based on that there's no such thing as a stupid question. I use a peak dca transistor tester. It measures a bunch of parameters: Vgs (off), Vgs(on), gfs, Idss, Rds. Which of these parameters should I be matching for using fets in a compressor ?
The two key parameters for FET matching are IDSS and the pinch off voltage both of which the pro model will measure so you should be good to go. I have been toying with buying one myself for some time. Do you think it is worth the money?I have the pro model. I can get it to curve trace if I hook it up to my laptop, but the software doesn't seem to have an obvious way to make comparisons. I emailed PEAK about it but they didn't respond.
It's quick & easy to use. In the main I just use it for testing transistors when repairing stuff for people. It does this well, but has a whole load more to it that generally I don't use, like the curve tracing for example. I guess there are probably cheaper boxes that would do what I mainly use it for. I wish they would make the software so that you could curve trace a bunch of devices & it would log the parameters maybe in spreadsheet format to make matching easier.The two key parameters for FET matching are IDSS and the pinch off voltage both of which the pro model will measure so you should be good to go. I have been toying with buying one myself for some time. Do you think it is worth the money?
Don't forget if you have an electrolytic cap in there you will need to reverse its polarity also.Well using a simple fet tester circuit I seem to have 4 matches quads from 21 fets, 2n3820.
When I say matched I mean with 10% of each other.
Just needed to reverse polarity for p channel as Ian said.
2 resistors 100R and 1meg and a 47uf cap with 3 way switch.