!! Breakthrough !!
I guess problem found !
Last attempt before removing Q6 to Q8 i decided to place a pot at position R11.
Now at 390 ohms, but 15mV offset.
I'll leave it in for a while to heat up. but things are looking good so far !!!
(cold air over Q1,Q2,Q3 drops offset to 3mV)
(i should have listened to this advice much earlier...
I guess problem found !
Last attempt before removing Q6 to Q8 i decided to place a pot at position R11.
Now at 390 ohms, but 15mV offset.
I'll leave it in for a while to heat up. but things are looking good so far !!!
(cold air over Q1,Q2,Q3 drops offset to 3mV)
(i should have listened to this advice much earlier...
![20160101_125050[1].jpg](/community/data/attachments/470/470534-715b37c3d8626cb14dbfd53b29b84765.jpg)
the box
I used the metal mesh to secure all components and have no attachment to the bottom of the box
I used the metal mesh to secure all components and have no attachment to the bottom of the box
Hi!
I am building an Aleph 5 clone and I would like to know if it is at all possible to change the outputs from hexfets to lateral FETS? And if possible, what has to be changed? I was thinking about something like this: FQA19N20C or FQA70N15.
I have no experience from experimenting with power FETS and I would be grateful for any help.
If substitution is not possible or advisable, I do have the IRFP240 and the IRFP260 in my drawer; which one is the best choice?
Thanks a lot, I really look forward to powering up the boards!
I am building an Aleph 5 clone and I would like to know if it is at all possible to change the outputs from hexfets to lateral FETS? And if possible, what has to be changed? I was thinking about something like this: FQA19N20C or FQA70N15.
I have no experience from experimenting with power FETS and I would be grateful for any help.
If substitution is not possible or advisable, I do have the IRFP240 and the IRFP260 in my drawer; which one is the best choice?
Thanks a lot, I really look forward to powering up the boards!
Yes you can do it. I am converting a Zen 4 to Lateral mosfet. I am unaware that Fairchild make lateral mosfets though.
If you have a circuit diagram that would help.
Most likely you will need to add a trimpot on the drain of Input mosfet for setting dc offset.
You will also need to change gate resistance values.
If you have a circuit diagram that would help.
Most likely you will need to add a trimpot on the drain of Input mosfet for setting dc offset.
You will also need to change gate resistance values.
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You will most likely need to change the value of R13 to set dc offset to Zero, depending on what mosfets you decide to use.
If you can fit a trimpot in there, it will add flexibilty in setting the dc offset.
Edit: I am reconsidering that thought, I'm starting to think the combination of Q4 and Q5 will ensure a zero dc offset, but possibly changing R13 to a higher value maybe necessary for some devices to ensure the device is on, certainly not necessary for true Lateral Mosfets. I'll Let Zen Mod confirm as he is far more experienced with original Aleph series.
If you already have IRFP240, there is absolutely nothing wrong with those devices though.
If you have 2sj313 that would be a worthwhile upgrade over irf9610.
If you can fit a trimpot in there, it will add flexibilty in setting the dc offset.
Edit: I am reconsidering that thought, I'm starting to think the combination of Q4 and Q5 will ensure a zero dc offset, but possibly changing R13 to a higher value maybe necessary for some devices to ensure the device is on, certainly not necessary for true Lateral Mosfets. I'll Let Zen Mod confirm as he is far more experienced with original Aleph series.
If you already have IRFP240, there is absolutely nothing wrong with those devices though.
If you have 2sj313 that would be a worthwhile upgrade over irf9610.
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I wouldn't bother chasing different outputs - just use IRFP240
they're peanut priced , so either buy them matched or buy enough to match your own (at 500mA)
agree about 313
also - it's wise to put 470R trimpot instead of R13 (set offset) , and series combo fo 150K fixed resistor+100K trimpot , in place of R17 (set Iq)
all that ref. to schm posted in #56
they're peanut priced , so either buy them matched or buy enough to match your own (at 500mA)
agree about 313
also - it's wise to put 470R trimpot instead of R13 (set offset) , and series combo fo 150K fixed resistor+100K trimpot , in place of R17 (set Iq)
all that ref. to schm posted in #56
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