Apologize for the delayed response. These ones I bought happen to be from Vishay, I didn’t see anything available from ST or Onsemi/Fairchild unfortunately, generally I buy On/Fairchild. I agree it’s very likely that they will be very close since they were all in the same run.
Do you mean the upright resistors connected directly to each gate? They are 100 ohms. Then every source has a 0.22 ohm.
I saw that they all had the matching resistors and figured that they were the balancing resistors as well.
It was here in DIY Audio all the time 🙂
Oh very nice! I made a little fet tester earlier on for testing small jfets, plans from here actually.
Basically just uses a precision 100 ohm resistor, found one that measured 100.00 ohms on both of my flukes, and then you apply 12v where it says “PS” and then measure voltage across the two test points there. I’m fairly certain the plans came from Nelson Pass, they’re for matching the jfets for his clone builds.
For your design needing a -15v supply, what would you recommend? I’m guessing a 12.6-0-12.6 transformer would be too small? I’m thinking full bridge rectifier then fed into a pair of voltage regulators??? How much current demand is there? I’m guessing not a ton, not sure how much waste on top of the 11 mA being passed, would TO-92 sized regulators work with a fairly small transformer? Would four small 1N4148s work for the rectifier being good to 200 mA, or would it be better to step up to a 1 A device like a 1N4001? Small filter, like a pair of 470uF or 1000uf caps for filtering once rectified? Just thinking off the top of my head. Regardless if the mosfets I have are close since they’re in the same production batch I’d really like to build your design for future matching.
Thank you so much,
Dan
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Mine is specific for power MosFets which I use by the truckload in my Musical Instrument amps, yours is the same case.
I mentioned +/-15V because that´s typically available in most amps to feed Op Amps, no need to build a dedicated supply, but if you do, 11mA needed here is "nothing", any transformer, diodes, capacitors will do.
Whatever you have in your junkbox.
No need for a precision resistor also, or a regulator, a few % difference is irrelevant; anyway all MosFets will be tested in the same device and we are matching one to the other, so ....
That said, if you want to build a nominal +/-15V supply for bench/general purpose use, go ahead, it´s always useful.
I mentioned +/-15V because that´s typically available in most amps to feed Op Amps, no need to build a dedicated supply, but if you do, 11mA needed here is "nothing", any transformer, diodes, capacitors will do.
Whatever you have in your junkbox.
No need for a precision resistor also, or a regulator, a few % difference is irrelevant; anyway all MosFets will be tested in the same device and we are matching one to the other, so ....
That said, if you want to build a nominal +/-15V supply for bench/general purpose use, go ahead, it´s always useful.
Yeah the only reason I think I need to build a power supply is because I don’t think I have anything else that would provide a negative 15v, I have a bench top ps that will do 30v and then another that will do 4000v, but nothing in the negative.
Dan