nxt version(better?)
Hello.
here is next version of my pcb, without emmiter resistor and with separate heatsinks for drivers.
BTW:
one more question: is heatsink needed for drivers in normal(one pair of power transistors) configuration in ESP3A? how big must be for HO configuration? on my board is not so much place...
all sugestions are welcome.
Hello.
here is next version of my pcb, without emmiter resistor and with separate heatsinks for drivers.
BTW:
one more question: is heatsink needed for drivers in normal(one pair of power transistors) configuration in ESP3A? how big must be for HO configuration? on my board is not so much place...all sugestions are welcome.
An externally hosted image should be here but it was not working when we last tested it.
Hello,
Use Protel if you an get it, it's miles above eagle. Protel have a different approach than Eagle, where everything is verboten. In P you can click one pad on a CPB and change it as you like. In Eagle you have to mess with the libs, get back to schematic, a long winding road.
The question about changing tracks to fill spaces in poured copper is resolved like this. Draw the desired width, update the power plane and it fills every possible area with copper, nice. As you can't get too much copper in the ground plane can you?
Andreas
Use Protel if you an get it, it's miles above eagle. Protel have a different approach than Eagle, where everything is verboten. In P you can click one pad on a CPB and change it as you like. In Eagle you have to mess with the libs, get back to schematic, a long winding road.
The question about changing tracks to fill spaces in poured copper is resolved like this. Draw the desired width, update the power plane and it fills every possible area with copper, nice. As you can't get too much copper in the ground plane can you?
Andreas
Olá, pessoal! Novidades sobre este assunto? Apesar de tanto tempo depois, pretendo montar um protótipo desses! Agradeço a postagem de novas experiências e dicas. Abraço!
Hi! Any news from this thread? Although being a quite old-fashioned project, I still intend to try mine! I thank any advice! Best regards from Brazil.
Hi! Any news from this thread? Although being a quite old-fashioned project, I still intend to try mine! I thank any advice! Best regards from Brazil.
i wonder in this old thread nobody bothered to tell that increasing the rail voltage adding more outputs and replacing a few LTP transitors will Not make a working amplifier ...
Ltp stages are calculted for a specific curent flow from the specific rails .... if rails are increased the ltp stage needs to be calculated again ....it will probably mean the same for almost everything such is the VAS stage and bias circuit
beyond that multiple out cfp can be trouble to stabilize
this is a no go project ....
Ltp stages are calculted for a specific curent flow from the specific rails .... if rails are increased the ltp stage needs to be calculated again ....it will probably mean the same for almost everything such is the VAS stage and bias circuit
beyond that multiple out cfp can be trouble to stabilize
this is a no go project ....
Tho not explained as good, it was mentioned there would be problems...but you are right, its just this single post ever mentioning any problems
Anyway, I am more interested in a "scaled down" version, with say 25Vdc rails, and quad pair outputs
Anyway, I am more interested in a "scaled down" version, with say 25Vdc rails, and quad pair outputs
Some CAD packages allow the use of power planes which fill in unused copper on each layer. Some even allow connection of the powerlane to a net(s).
Personally I prefer to just fatten tracks to decrease their impedance.
I had the same needs. I would like to adaptethe project to low voltage - hi- current situations, like 3 Ohm speakers with 35 Volt rails.Anyway, I am more interested in a "scaled down" version, with say 25Vdc rails, and quad pair outputs
I have seen some doubled output schematics, but they look a little too redundant to me.
I might propose something more "extreme"...
View attachment S-LAZYP3sch.pdf
I have eliminated Collector resistors (I do hate them..) and added only a small (1W) degeneration resistor on the drivers.
I know, I should put ab. 2.2 Ohm base resistors on the Output devices, but I am afraid this will slow down too much the response. I believe mounting everithing on a compact PCB this should work and more than all preserve the beatiful sound of the original P3A. I did not simulate, nor made big calculations, it's just an idea. Do you think it is feasible ?
effebi
from my point of view there is a few drawbacks one wil be that with this output configouration it might be not easy to stabilize the choise of VBE i dont like ...a simple BD 135 will just fine then again might be possible to need changes in the miller caps ...and of course using cans might cause complications in the pcb
Yeah right, For VBE any good BJt will work, just i wanted to keep the same TO220 case. Then I feel that having the same junction may give some some little adavantage in thermal compensation ( I my idea the drivers and the VBE share the same small heat sink). Then I know, I might cause oscillation, like any other topology like this.
Cans where uses for decades, and have non particular disadvantages in my opinion. The have generally a MUCH better thermal behaviour. But what about the way the output stages are coupled?
effebi
Cans where uses for decades, and have non particular disadvantages in my opinion. The have generally a MUCH better thermal behaviour. But what about the way the output stages are coupled?
effebi
#1 disadvantage is that you need to wire them from the pcb .... unless you have a clever pcb heatsink combo
can this output stage work and be stable?
Yes, exactly, I was designing a separate PCB for the two final pairs and their emitter (and base if wanted) resistors. The elimination of the output collector resistors, other than energetic considerations was done for simplify the wiring between the boards (two wires less).
BTW Another advantage of the TO3s is that you can use nice sockets for them (I know some cheap ones are bad, but I have a long practical experience with the good ones).
The BIG question is does such output schematic stage work stable? I am afraid that the running of the drivers Emitter current through the Final collector Resistor in the original had an improved effect on the local feedback than using a separate emitter resistor just for the driver.
Please have a look on the attached schematic.
Thanks
effebi
Yes, exactly, I was designing a separate PCB for the two final pairs and their emitter (and base if wanted) resistors. The elimination of the output collector resistors, other than energetic considerations was done for simplify the wiring between the boards (two wires less).
BTW Another advantage of the TO3s is that you can use nice sockets for them (I know some cheap ones are bad, but I have a long practical experience with the good ones).
The BIG question is does such output schematic stage work stable? I am afraid that the running of the drivers Emitter current through the Final collector Resistor in the original had an improved effect on the local feedback than using a separate emitter resistor just for the driver.
Please have a look on the attached schematic.
Thanks
effebi
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