to dantwomey
Hello dantwomey,
I use the 'oldtimers' LM317 / LM337 pretty often. I often add a CRC filter in front of the LMs. There are more modern voltage regulators which produce lower noise.
But I used the LM317 for my 50W-SE-Schade-amp to adjust the bias voltage.
This is a great amp!
Greets
Dirk
Hello dantwomey,
I use the 'oldtimers' LM317 / LM337 pretty often. I often add a CRC filter in front of the LMs. There are more modern voltage regulators which produce lower noise.
But I used the LM317 for my 50W-SE-Schade-amp to adjust the bias voltage.
This is a great amp!
Greets
Dirk
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Then I am 0,0001% of ZM.
I am still working on the project to find the holy grail of dumbness! 😀
Greets
Dirk
I am still working on the project to find the holy grail of dumbness! 😀
Greets
Dirk
Texas Instruments make new model of TL431
https://www.mouser.fr/ProductDetail/Texas-Instruments/TL431CLP-Z?qs=byeeYqUIh0P3%2BPlwAfHTLA==
https://www.ti.com/lit/ds/symlink/t...ll-mousermode-df-pf-null-wwe&ts=1597441032452
Perfect for Papa bias circuit
https://www.mouser.fr/ProductDetail/Texas-Instruments/TL431CLP-Z?qs=byeeYqUIh0P3%2BPlwAfHTLA==
https://www.ti.com/lit/ds/symlink/t...ll-mousermode-df-pf-null-wwe&ts=1597441032452
Perfect for Papa bias circuit
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Thanks to all the posts here I have completed my bias circuit, made the PCBs, and it works perfectly!
Regards,
Dan
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Soundhappy, the circuit that you posted has minimum output of 6.25V - too high.
Dan, your circuit has minimum output of 4.54V. That may or may not be low enough for IXFN140N20P. For THF-51S, that is probably too high for a large percentage of samples as the variability of Vgs is high. I used a 5K pot in my build (otherwise same circuit) and that outputted a minimum of 3.0V.
Dan, your circuit has minimum output of 4.54V. That may or may not be low enough for IXFN140N20P. For THF-51S, that is probably too high for a large percentage of samples as the variability of Vgs is high. I used a 5K pot in my build (otherwise same circuit) and that outputted a minimum of 3.0V.
@ Ben Mah
From article is adjustable 4v~12V bias circuit
Source : http://www.firstwatt.com/pdf/art_sony_vfet_pt1.pdf
I like very much precision of multiturns trimmer 😉
From article is adjustable 4v~12V bias circuit
Source : http://www.firstwatt.com/pdf/art_sony_vfet_pt1.pdf
I like very much precision of multiturns trimmer 😉
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I have a half dozen PCBs so if I run into trouble I can make up a spare with a 5k pot. Thanks for the info.
Regards,
Dan
According to my calculations based on Ti datasheet:
Vmin = 2.5V(1 + 7500/5000) = 6.25V
See page 19 Figure 21:
https://www.ti.com/lit/ds/symlink/tl431.pdf?ts=1597519339702&ref_url=https%3A%2F%2Fwww.google.com%2F
Vref = 2.5V
Iref = 0.000002A so Iref x R1 = 0.000002 x 7500 = 0.015V, not significant
Vmin = 2.5V(1 + 7500/5000) = 6.25V
See page 19 Figure 21:
https://www.ti.com/lit/ds/symlink/tl431.pdf?ts=1597519339702&ref_url=https%3A%2F%2Fwww.google.com%2F
Vref = 2.5V
Iref = 0.000002A so Iref x R1 = 0.000002 x 7500 = 0.015V, not significant
I initially used the same exact circuit with those exact values in post #1267. I was not able to go lower than 4.5V, which in turn prevented me from setting D-S at 28V on the lower IXFN. The 5k pot was the only change I made which remedied this.
I build TL431 circuit long time ago...
and from my experience 4.7V is a perfect bias voltage for Schade 50 mosfet.
Work like a charm
I should have put the caveat 'YMMV'.... my fets must've been made on Friday😀
