NP stated that the BOSOZ design does not strictly require matching of the MOSFET pairs. But I decided to order extra parts and match them, just to learn.
I used the procedure in the PassDIY article, except that my available power supply is +12V, not the +15V described. I used a 1.6K resistor to keep the 5 mA current described by NP with my +12V. I made my measurements, and selected the best-matched pieces. So far, so good.
Then I noticed a statment in the BOSOZ article: each MOSFET will pass 40 mA in operation. Does that mean that the matching needs to be done with 40 mA of current to be correct?
Ren
I used the procedure in the PassDIY article, except that my available power supply is +12V, not the +15V described. I used a 1.6K resistor to keep the 5 mA current described by NP with my +12V. I made my measurements, and selected the best-matched pieces. So far, so good.
Then I noticed a statment in the BOSOZ article: each MOSFET will pass 40 mA in operation. Does that mean that the matching needs to be done with 40 mA of current to be correct?
Ren
H Ren,
I matched those mosfets also. I found that the Vgs varies when temperatures change. So for a few seconds i used a Ids of approx 100mA to heat the mosfets. Then i switched to the 40 mA like the articles says. Next thing i did was wait (for 10 or 15 minutes) so that the temperature of the heatsink and FET's dropped to normal.
By doing so i could make pairs of FET's with only 1 mV difference.
You'll need a few hours of free time to do it
Good Luck,
Nick
I matched those mosfets also. I found that the Vgs varies when temperatures change. So for a few seconds i used a Ids of approx 100mA to heat the mosfets. Then i switched to the 40 mA like the articles says. Next thing i did was wait (for 10 or 15 minutes) so that the temperature of the heatsink and FET's dropped to normal.
By doing so i could make pairs of FET's with only 1 mV difference.
You'll need a few hours of free time to do it
Good Luck,
Nick
If you want to be medieval about your matching,
you will use the same currents as the application,
but a lot of the time you'll find that that matching
at 5 ma tracks well enough to get you a decent
match at 40 ma, so I wouldn't worry.
There is so much resistance in series with the Sources
on BSOZ, that it doesn't matter much in any case.
you will use the same currents as the application,
but a lot of the time you'll find that that matching
at 5 ma tracks well enough to get you a decent
match at 40 ma, so I wouldn't worry.
There is so much resistance in series with the Sources
on BSOZ, that it doesn't matter much in any case.
Hi ,Nelson!Nice to see you throug the net.
Last year I had tested ablout 100 pieces of irf9610s with the method on web passdiy.com. The difference between the mosfets is small, the biggest tolerance is less than 10mv.I'm sure ,it's true.Through the test I got 8 couple of mosfet.In December I'd made the Aleph3. The DC offset of the both channels is around 60mv.In despite of very much effort I paid ,it i was no use.I cann't understand it. Recently I want to built the Aleph X. Is there any better way to match the irf9610?Any suggestion will be apreciated.
THX to Nelson .
Last year I had tested ablout 100 pieces of irf9610s with the method on web passdiy.com. The difference between the mosfets is small, the biggest tolerance is less than 10mv.I'm sure ,it's true.Through the test I got 8 couple of mosfet.In December I'd made the Aleph3. The DC offset of the both channels is around 60mv.In despite of very much effort I paid ,it i was no use.I cann't understand it. Recently I want to built the Aleph X. Is there any better way to match the irf9610?Any suggestion will be apreciated.
THX to Nelson .
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