813 Based Amps

[boiss]

I have been rather busy with other things lately but haven't lost interest. Have just about finished my toroidal O/P tranny at least the primary. I tried the compass idea and it appears to work at least with pure DC. I set one winding at a certain current and vary the current in the other, the compass registers the difference if it is about 3mA or more, which seems quite sensitive. Once I get the valves hooked up to it will be the acid test.
I found a circuit simulation program "Multisim" by National instruments, It's an evaluation copy valid for 30 days so I've been trying out circuits for the phase splitter. The valve types are a bit limited though. Tried with a 12AT7 running with 400V supply and with 2x 6V6 triode strapped running with 600V supply. 100Vpk/pk into 30k is just about possible with the 12AT7, with the 6V6 there is no problem at all to get 150V pk/pk and square wave performance at 20Hz is pretty good too unlike the 12AT7.
For testing I reckon I will knock up the 12AT7 lower gain phase splitter circuit which gives about 50V pk/pk with reasonable 20Hz sq wave performance and an I/P of 2V pk/pk.
All of these circuits are long tailed pairs.
I haven't managed to get any sense from the distortion measurements with the tool. It says that 2nd and 3rd Harmonic distortion are at about -4000dB, obviously it's a super super design!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Anyone else tried this program?
Mike.

[Ed_Dinning]

Hi Mike, this was a programme I evaluated some time ago, it's great for analogue use, but can fall down badly on power electronic circuits as it does not model all the strays and parasitics. Let me know how you get on.

Ed