Simple Symetrical Amplifier

[Joachim Gerhard]

Klippel is working on a model for 40years. I think his latest model has 100 plus components.
This is just a basic overview :http://www.klippel.de/fileadmin/klip...ity_Poster.pdf
Why not connect a speaker while measuring ? OK; it gets pretty nasty loud.

[shaan]

Originally Posted by Esperado

I do not understand why they do not provide an easy square waves generator, where you set the frequency, the level, and the offset... and, by default potentiometers, trasfos, and some other very ordinary parts we use all the time.

Hi Christophe.

Simetrix is the answer. I use it to sim everything from solid state relay to resonant ZVS flyback converter to SSA.

It has an easy square/sine/saw/triangle/pulse generator with offset/delay and other parameters. Also a bidirectional pulse generator, potentiometers, electrolytic caps, inductors and transformers. All with settable parameters and a very easy interface.

[Esperado]

Originally Posted by shaan

Hi Christophe.
Simetrix is the answer.

Thanks a lot, Shaan, i will try this.

BTW; interesting sims, may-be ?
My amp CFB vs VFB. The two sims are from the upper input VAS stage.
Don't compare the two low and high ends frequencies, the CFB is bandwidth limited for production, while VFB tuned to explore extremes.

[keantoken]

The graphs are difficult to compare because the scales are not synchronized.

Both CFB and VFB depend heavily on implementation. I'm not sure what part of the circuit these traces are from but I would guess the input stage for the VFB version has much higher transconductance necessitating more compensation to load it down enough at RF to stabilize it.

If the traces are taken from the VAS input, then the rail voltage variations will be added to the signal, obscuring the actual behavior of that node. Unless you used perfect voltage sources for the supply.

[Lazy Cat]

CSA prototype functional at last. Today I installed output BJTs, so the output BIGBTs are finally completed. Closed loop stability compensation scheme without any change as expected, output bias tested up to 0,5 A, DC offset +/-10 mV, very stable output. Sine waves from generator OK, 100 kHz square waves OK. The only thing left to finalize is temperature compensation for the main heatsink, 10 k NTC used as temperature sensor (pic), only 15 pF from NTC to housing (case GND) means also from VAS output to GND.
CSA's next stage is to finish the second channel and housing with heatsinks, toroids, etc.

[lanchile]

Originally Posted by Lazy Cat

CSA prototype functional at last. Today I installed output BJTs, so the output BIGBTs are finally completed. Closed loop stability compensation scheme without any change as expected, output bias tested up to 0,5 A, DC offset +/-10 mV, very stable output. Sine waves from generator OK, 100 kHz square waves OK. The only thing left to finalize is temperature compensation for the main heatsink, 10 k NTC used as temperature sensor (pic), only 15 pF from NTC to housing (case GND) means also from VAS output to GND.
CSA's next stage is to finish the second channel and housing with heatsinks, toroids, etc.

What and why are those wire soldered to the fuses?

[Lazy Cat]

Originally Posted by lanchile

What and why are those wire soldered to the fuses?

hehe in testing phase instead of a real fuses, blown ones takes their place. Those wires connects 25 ohm/20 W resistor on both rails to prevent any outputs damage when closed loop stability is calibrating to optimal local feedback C. I use trimmer C on both VAS sides to find optimal capacitance. In CSA they're around 10 pF.

[Lazy Cat]

Two C trimmers for compensation on pic. When settled to optimal value, they're replaced with fixed ones.

[Esperado]

L.C ? Did you have time to provide the differential input SSA sim file ?

[Esperado]

Originally Posted by keantoken

The graphs are difficult to compare because the scales are not synchronized.

Look at the phases sens and what happens around 1Khz. This does not change whatever the current values.