My (poor) excuse is that it's the default orintation for PNP transistors with LTSpice and all other simulators I've used have the emitter pointing upward as the default for PNP transistors.
Hi Ron,
I noticed that too, at 1 MHz and above it looks a bit "playfull".
on1aag.
Yes, as it now has more gain, it ocillates around 500mV at about 1MHz.
I've experimented a bit with the compensation capaictors and for some reason increasing their values makes it worse not better.
I came to the conclusion that they got a bit carried away with the compensation capacitors, removing C2 solves the problem, it only adds another phase shift which makes it more prone to oscillation.
Sounds good. I will do that along with a minor change to the emitter - follower circuit. I would like to use Darlington pair. Doing so I need to add 2 more diodes. The signal frequency will be varied from 6Hz - 60Hz so I probably won't have any issues with gain roll-off. I never dealt with switching amplifiers or components before so I doubt I can design a Class D amplifier at this point. So I will just stick to linear for now.
Thank you for your help.
It looks like you're building an inverter.
This isn't a very good way of doing it, PWM or modified sinewave is better.
Are you intending to use this to control the speed of an AC motor?
If so it might not work with a single phase motor. The motor cerainly won't start at 6Hz as the starting mechanism is frequency sensitive. You could have a go at running it at full speed, then slowing it down which might work.
Another thing is that at low speeds the voltage must be reduced to avoid core saturation. With a PWM or modified sinewave inverter this is easy, the duty cycle is just reduced.