Zen with GA10JT12

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Thanks, Nelson. I read it while driving home. 🙂
 

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I was wondering how foolproof the biasing circuit is.
Particularly, if anything happens to the opto while ageing, what is going to happen to the power Mosfet ?

Wouldn't the addition of a resistor in parallel with the biasing transistor (the one in blue below) provide some safety in case the opto fails (imagine the gate would be at +Vcc voltage). Something around 500 Ohm to provide a gate voltage of 1V or so
What do you think ?

GA10JT12_dchematic_modified.png
 
I believe I'm aging faster than that opto

:rofl:

OK, I'm also trying to confirm that I understood the design properly.... could this at least be a good safety measure to take ?

TBH the idea came to me as I was contemplating putting the opto on an IC socket, (so as to try what various opto types would do to the sound) and wondered what would happened if the contact was not properly done

I guess my question should have been: is the opto critical to the sound ?
From my LTSpice simulations, R7 and R5 values are very critical to the biasing depending on what opto you use 😛 ...

Fred
 
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opto is governing element of CCS , not some Voodoo approved part

so , CCS is either working properly , at current intended ....... or is intended current altered using some other opto , so you need to alter resistors to go back to intended current

so , to conclude , when working properly - opto is invisible soundwise

also - putting resistor in parallel with bjt opto-part , whichever reason you have , will alter function of opto itself

so , speaker is pretty much safe due to existence of coupling cap

put appropriately sized sloblo fuse in rail and you done everything needed

that opto will outlive you too , most probably
 
This thread has went to sleep. Any players? It appears to me that the voltages can be achieved with a typical FW PS with a slight reduction. The device has nice curves. I stumbled upon this thread doing some research on the F3, Zen 9 builds. I read NP article when it came out but diverted to another path. Q3 = 4N35 as in M2?
 
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Main interest these days seems to be PP with hockey pucks. Wish I was younger and could use learn spice sim's.

Yes projects with hockey puck's are fantastic....Diyers who want try other technology silicon carbide transistors
GeneSic GA10JT12 can do the job.
Rare Semisouth's become "unicorns" and prices was skyrocketed.

http://www.mouser.com/ds/2/169/GA10JT12-247-553277.pdf

http://www.mouser.fr/ProductDetail/GeneSiC-Semiconductor/GA10JT12-247/?qs=rJ%2bziJWpyswlGCmHhheLLA==

Ooouh no one actually in stock....but can be in command
 
What sort of SE amplifier would you like to see made with the 2SJ28?

*Sorry, just realized this is a thread about the GeneSiC, so I'm off-topic.

Hi Mike, I have seen your SE schematics using these V-fets and have seriously considered building it using my extra J28's. About that time NP said he would see what he could work up using the V-fets in SE not that it would be better but.....

You are right we should not stray any further away from topic.
 
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