How much longer will we be able to get old fashioned hexfets from places we trust? That’s the $64000 question.
The love them so much that they won't sell them🙁
Vishay still makes them.
Since 2015? when they bought International Rectifier
WOAH !!! they on drugs LOL
OnSemi 1.70$ and usually around 1.97$ anywhere else.
They will likely get a taste of reality when new production comes in.
Someone should Email them and let them know that the package isn't obsolete.
And price Gouging like that is absurd.
Good catch.
When is Vishay going to stop making them, and you have to buy from ISC - thats what I was getting at.
BTW, Microchip is always on drugs. They make stuff for industrial-military use primarily. When the cost of updating all the design documentation and QUALIFICATION far exceeds the cost of paying too much for exact replacement parts.
If you want to be sure components are still available in a decade or two, build a valve amplifier. 😉
No, not listed by Vishay
And no, these where Fairchild Mosfets
Fairchild has been bought by On-semi,
IR by Infineon.
With or without Q5 and Q9, shouldn't there be a diode in parallel with C5 to ensure that the current through Q16 doesn't go excessively high during clipping and also to prevent polarity reversal when Q6 saturates? Alternatively, there could be an extra transistor monitoring the voltage drop across R10: emitter to the supply, base to R10, collector to the base of Q16, R10 half the value of R14.
Correct
Maybe your confusing comments about the Fairchild Mosfets and IRF mosfets
OnSemi is current manufacture for mentioned Fairchild mosfet.
The reactivated status and location change for manufacturing is yes from a OnSemi PCN notice.
noted post #58 so with 47 week lead expect new production arriving in August
Never claimed Vishay made them, it was for another comment
Forgot Vishay was buying up sections of IR back in 07
Yes Infineon was around 2015.
I just liked @minek123 mosfet amplifier he posted. It is still feasible for other vertical/hexfet mosfets.
Was just a helpful example for the OP's mosfet curiosity
And the "Good Enough" status for the OP holds.
There is the usual updates expected from the learning process.
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It's certainly a good idea to use very common valves. I was joking, of course, but only partly.
In 1994, I made an amplifier using the very common BUZ10 power MOSFETs that were made by many manufacturers, CA3046 transistor arrays that had been in production for decades and had LM3046 as second-source equivalent (and CA3086 would have worked as well), BC546...BC550 and BC556...BC560 transistors and TL071 op-amps.
The BC5xx transistors are still available and the TL071 as well (although you have to be careful with those of TI nowadays), but BUZ10 MOSFETs and CA3046/LM3046/CA3086 transistor arrays are nowhere to be found anymore. Had I made a valve amplifier with EL84 and ECC83 valves, they would still be readily available.
In 1994, I made an amplifier using the very common BUZ10 power MOSFETs that were made by many manufacturers, CA3046 transistor arrays that had been in production for decades and had LM3046 as second-source equivalent (and CA3086 would have worked as well), BC546...BC550 and BC556...BC560 transistors and TL071 op-amps.
The BC5xx transistors are still available and the TL071 as well (although you have to be careful with those of TI nowadays), but BUZ10 MOSFETs and CA3046/LM3046/CA3086 transistor arrays are nowhere to be found anymore. Had I made a valve amplifier with EL84 and ECC83 valves, they would still be readily available.
Or a 6L6GC, EL34, KT88 ... basically any tube that has guitar use. I suppose another point, nobody seems interested in relabeling or faking a vacuum tube, only transistors.
[Sorry for the cross posting. I accidentally posted it to the wrong thread]
Alright folks, I made some mods:
1) Added drivers. Increased the slew rate from 12V/us to 14V/us. THD still at 0.003%
2) Turned the front end upside down, i.e. swapped NPN and PNP. That increased the slew rate from 14V/us to 19V/us. THD still at 0.003%
3) Doubled the current through the VAS to 14mA. THD decreased to 0.0001% !!!
Thank you for all the feedback! The best part is that it's still made from bog standard components. Hopefully I have time to redraw the PCB this weekend so we get to find out what it sounds like! The only downside is that it's even more mundane and ordinary in its design, now that I took out the quirks.
Alright folks, I made some mods:
1) Added drivers. Increased the slew rate from 12V/us to 14V/us. THD still at 0.003%
2) Turned the front end upside down, i.e. swapped NPN and PNP. That increased the slew rate from 14V/us to 19V/us. THD still at 0.003%
3) Doubled the current through the VAS to 14mA. THD decreased to 0.0001% !!!
Thank you for all the feedback! The best part is that it's still made from bog standard components. Hopefully I have time to redraw the PCB this weekend so we get to find out what it sounds like! The only downside is that it's even more mundane and ordinary in its design, now that I took out the quirks.
My bad! I had forgotten to adjust the VBE for the higher current, so it was running in Class A. With a more reasonable quiescent current of 180mA, THD is 0.0003%. Still not bad!
Thanks! Much better. I also lowered the LTP current to 600uA. Current through the first VAS transistor is now limited to 15mA.
However... Wouldn't a, say, 2.2k resistor between the emitter of Q13 and the base of Q10 have the same effect? It would limit the current flowing out of the emitter at Q13 and raise the voltage at the same emitter, both contributing to a lower power dissipation. Voltage and current across Q13 are effectively out of phase, limiting the power dissipation. The only issue is that I get a brief spike of about 180mW when the voltage and current waveform cross. Your solution feels more solid, though. Might be worth that dirt cheap transistor. 🙂
