I wanted to build a variation of the Amazing Circlotron with Exicon Mosfets and positive current feedback. I emailed Mike and have his blessing. I came up with the circuit below but I have a nagging feeling it wouldn't work. I suspect that the PCF should be cross-coupled to the load and the ends of the 0R33 resistors grounded, but don't want to blow up my working amp with the modification. Sorry poor man's workshop, no Spice etc and a solid state beginner. Would like some advice as to the connection of the positive current feedback.
Regards Tony
Regards Tony
Not that one for sure. Better simulate, you need to use LTspice to even begin this stuff.
Better to reboot than to rebuild, it's much faster.
Better to reboot than to rebuild, it's much faster.
Thanks Rayma, took the plunge and downloaded LTSpice. Tried to take lhquam's Type 2 F7 topology and apply it to the Circlotron and I can see problems with both drawings. Anyway after some LTSpice learning I may have something that works in time.
Keep in mind, somewhere on each polarity there is a resistor that senses the output current. This produces a signal which adds to the output voltage. You will see this clearly in the F7 schematic. You can do this with a fully differential circuit as you propose, but it gets a little more complicated than simply looking at the output current to ground via a resistor from speaker minus to ground. Nonetheless it is do-able.
Thanks Nelson, succinctly putting my issue with my two proposed circuits. I got the "F7 way" but "mirroring" the circuit didn't add up as in the second drawing. I have looked at lhquam's balanced F7 (circuit below) and thought this might hold the key to implementing. There are four output devices in a bridge, whereas a Circlotron has two devices and two power supplies in a bridge. Anyway once I master Spice will have another crack at it.
and thought