I made a video here:
to show my current test setup for some IRP240 mosfets I am trying to profile for JLH-M and PLH projects.
Not getting expected VGS values?
to show my current test setup for some IRP240 mosfets I am trying to profile for JLH-M and PLH projects.
Not getting expected VGS values?
Can't tell much from the video as there are wires everywhere, the camera is constantly moving, so can't tell whether the circuit is wired correctly or not.
Pictures showing the whole setup with wires separated so that the wiring can be followed from component to component and to power supply would make trouble shooting easier.
Some things to check:
-measure the voltage drop across the resistor. The sum of the voltage drop across the resistor and the mosfet should equal the power supply voltage.
-measure the resistor's resistance. Is it 56 Ohm? Is it 2W?
-double check all connections. You could simplify by eliminating the board and connect everything directly. There are only two components and a power supply.
-try another mosfet.
Pictures showing the whole setup with wires separated so that the wiring can be followed from component to component and to power supply would make trouble shooting easier.
Some things to check:
-measure the voltage drop across the resistor. The sum of the voltage drop across the resistor and the mosfet should equal the power supply voltage.
-measure the resistor's resistance. Is it 56 Ohm? Is it 2W?
-double check all connections. You could simplify by eliminating the board and connect everything directly. There are only two components and a power supply.
-try another mosfet.
Hehe, I know it’s not pretty setup but i've double checked it and everything seems connected well. I tried another MOSFET IRF140 and I get 7.62v.
The circuit is not complicated here is a photo.
With IRFP240 I get 8.63vDC for VGS and across the 56 Ohm 2w resistor is 6.19vDC
The circuit is not complicated here is a photo.
With IRFP240 I get 8.63vDC for VGS and across the 56 Ohm 2w resistor is 6.19vDC
Well, I am nearly out of ideas. I see that you have some power resistors. Use them to check your power supply to see that it is not limiting its output current. I can see the CV light is lit, but it doesn't hurt to check.
Here's another thought: measure the Vgs directly at the mosfet, in case the wires are adding resistance and dropping voltage.
I'd expect Vgs in high 3V - low 4V range on the IRFP240. At one point I thought it was clever to graph the results of a batch I did. See the results. The last batch of 1000x 240's I did trended higher.
I made a matching jig based on Nelson's article. I've run a few thousand through this schematic. I forget the resistor values. Higher current is for 240 & 9240, low current is for 9610's etc.
I made a matching jig based on Nelson's article. I've run a few thousand through this schematic. I forget the resistor values. Higher current is for 240 & 9240, low current is for 9610's etc.
Attachments
lol, this is nuts I spent all afternoon trying to get this little circuit working funny as it sounds... what I can tell its working albeit with some unexpected results:
I test 3x IRFP240 and all were between 8.2-9.0v VGS.
I tested 3x IRFP140 and all were between 7.5-8.2v VGS
More interesting is I tested 3x MITSUBISHI FS70SMJ-06 (used in vintage Sony ES power amps) 3.0-3.2v VGS
I test 3x IRFP240 and all were between 8.2-9.0v VGS.
I tested 3x IRFP140 and all were between 7.5-8.2v VGS
More interesting is I tested 3x MITSUBISHI FS70SMJ-06 (used in vintage Sony ES power amps) 3.0-3.2v VGS
Those a wrong numbers - sorry. These parts have Vgs between 2 and 4 volts. Most I have seen were between 3 and 4.
Solved - I found that one of my breadboard jumpers was damaged/pin was blackened! Now I can get 3.86 VGS on one IRFP240.
I'm not a fan of breadboards! to make the match of the irf9610 yes ! But for the power mosfets I use a thousand holes and with terminals to connect the pins of the mosfets!
You can send me your parts for matching by curve tracing. That will provide you with much better matching than just a single Vgs value.