Yes I know, thanks to your delivery.
I should wrote if any other types of VAS transistors like BD139/140 are used, than mica insulators are mandatory. 🙂
Hi LC,
To switch to 16A output devices, is swap from 2SC3503/2SA1381 to BD139/BD149 sufficient?
Marc
To switch to 16A output devices, is swap from 2SC3503/2SA1381 to BD139/BD149 sufficient?
Marc
Tell us the differences with the "similar schematics" so we can
understand where are the innovations....🙄
That s the same circuit but with a mosfet output stage instead
of the darlingtons....
Innovations, who said anything about that? Do you see my statement incorrect or offensive in any way? Why should I tell you anything? BTW if you don't like it here, just skip forward please.
OK for few parts more you get VSSA symmetrical amp with, as you've already said, better performance.
I make symmetrical amps only, that's my choice and I will stick to it in the future.
The following statement is not true :
This amp is a copy cat of Gabor s old amp , so just give credit
where it is due rather than talking of "non similarities" that are
just hollow words since you d be hard pressed if asked to find a single difference.
VAS BJT's are more like hFE, fT and Vce max parameters importance, since collector current is only 15mA and power dissipation around 0,5W. So any high performance NPN/PNP complemenary pair in TO-126 case is just fine here. 😎
If Alex won't find time to make one of his probably the most compact PCB here, than I will go for it. Lets make some smokin' VSSA as a 
Hi LC i playing at this time with eagle...
First for TO3 as ia had layout for TO3 Lateral SSA. Will show you as it been ended. After it's easy to swap to plastic case.
Marc
First for TO3 as ia had layout for TO3 Lateral SSA. Will show you as it been ended. After it's easy to swap to plastic case.
Marc
I do not know how to say this. But such a circuit i have rejected as the VAS transistor current accelerates very fast to dangerous level without very good cooling.
As they get warmer they get higher hFE and lower VBE drop -> more current -> hotter -> higher hFE, lower VBE -> more current -> hotter ... Get the picture??
Yes but there's certain limit level of input collector current reached when it is thermally stabilized. 15k resistor defines max input collector current, also VAS collector current rising itself will stop when heatsink power dissipation reaches certain temperature. It is perfectly normal process as long as input is stable and not forcing VAS current over the limits in a cummulative process.
Of course as I already mentioned in post #39, VAS BJT's needs them, could be one common or two separates.
This project is fixed in complexity and will stay as it is. PCB will be our Christmas gift to DIY-ers for these long winter evenings hehe
Of course as I already mentioned in post #39, VAS BJT's needs them, could be one common or two separates.
This project is fixed in complexity and will stay as it is. PCB will be our Christmas gift to DIY-ers for these long winter evenings hehe
Matchbox kits??? 😉
PCB will be our Christmas gift to DIY-ers for these long winter evenings hehe
İts Christmas gift 🙂
An externally hosted image should be here but it was not working when we last tested it.
Super Cool Marc
Here first attemp...107*93mm; Size could be smaller but 10µ polycaps and 2200µ 40v too. I have some improvement in mind to deduce pcb dimensions
Marc
