Kevin Weddle

Hi AN920. I looked at your square wave inverter again. It looks like at 50% duty cycle oscillator, both outputs produce 25% duty cycle. Reducing the duty cycle of the oscillator means that both outputs have even lower duty cycle, and the two waveforms are offset from each other. Now I am just wondering why there are two mechanisms for lowering the duty cycle. Am I getting your design at all?

I see. The emitter resistor has little affect on the amount of feedback or phase shift. C5 divides by beta making the feedback almost totally capacitive. That means the collector signal is in phase with the emitter signal. Too strong a base signal would put the base signal in phase with the emitter signal and then the emitter signal would be out of phase with the collector signal. And so on... It's interesting that since all the positive feedback reaches the emitter base junction, the gain produced by the LC is not affected, otherwise the LC would be lowered by the parallel resistance.

I think the simulation is wrong. I don't see where you would get a change in response at Xc = 13000.

Hello AN920. Your square wave inverter circuit produces a clock and a clock not? Why does it have so many gates and how does the flip flop help. A flip flop has an extra gate of time delay, which would conflict with that parallel gate.

I bet you can use phone SIM cards in other applications. I have seen all sorts of high technology products used in custom test jigs.

Walid, I think the response is flat where the reactance equals the resistance. The lowest value always carries the most weight. But when they approach each other in value, the impedance is severely affected by both.

The signal at the emitter of the oscillator leads the collector signal by 90 degrees because of C7. That means the emitter lags the base by 90 degrees. I also understand that simple oscillators are just that, simple. They are not signal amplifiers.

Class C used for power audio creates an abridged version of the audio signal. And that means you lose a lot of what was in the audio signal. The oscillator looks like it has 90 degrees feedback. Have you tested this transmitter with a simple receiver? How does it sound?

I was talking about the oscillator itself. If we were to take away the modulation, the oscillator would be of a certain quality. Your saying the LC produces a good oscillator regard less of the transistor operation. The change in collector current looks excessive. But your saying it has no affect on the sinewave produced.

A PLL has to control the output of a VCO to make a good sinewave. If you don't control a parallel LC circuit, how can it make a good sinewave regardless of how the transistor is operated? I would think a transistor operated most linearly would make a better sinewave.

An hfe = 6 makes for a real low input impedance. Since the collector current is a fraction of the emitter current, the output signal size is less. If your VCE isn't high like the 20V shown in the data sheet, your hfe will be even lower. Also, the more you change the hfe by a high change in collector current, the less linear the reproduction. Audioguru, with a tank at the collector of a transistor, the collector averages out at the supply voltage? So a DC supply of 9v might go 10v to 8v?

That's what it was, an empty metal box with a cover.

If your using a power source, like the secondary of a transfomer to run the motor, why do need a start capacitor? The power source has enough power.

If the transfomer is center-tapped, you could get +- 12. Then add parallel regulators for as much current as you need. 25A is a lot of DC currrent. Otherwise, they make good variable regualtors with high input voltage and any ouput voltage and good current. Or you could throw in some high power transistors to step down the voltage. It's a little more complicated because you have to design it around your usual load. If the load is light, you 'll need a shunt.

Is there any relevance to this concept? I use reactance for phase calculation, and I can't think of where the current/voltage phase relationship is ever used. I just figured that if I had a capacitor in an AC power application, I could add an inductor somewhere and get more power. Maybe that's why motors have capacitors.

I think the rotor would have to be of the permanent magnet type. Sometimes it's all electromagnetic, which requires AC power. Let us know if it works.

Does current that is out of phase with voltage mean lower available power. I see inductors used everywhere in power supplies, but are they used for more than ripple reduction?

You may want to post in the microcontroller section, MP is good at that stuff.

I think maybe you would determine the reactance. Resonance will give you better filtering, supposedly. I had resonance give me 20db/decade one time.

A voltage clamp. A voltage doubler uses clamping action to get higher voltage,

I have seen what appears to be part of a clamper on the microwave transformer. But I couldn't find the rest of the circuit. And the magnetron is just an empty box.

I think the circuit should use a PUT. I think SCR's are more often used high current. SCR's are the hard ones to turn off. I wonder why PUT's are not used more in switching applications?

I'm not a programmer, but serial communication is still widely used. I think the code is more extensive and the harware more elaborate for parallel port usage. Buffering would be my main concern if using your own computer.

My car runs great for it's age. It's really too bad though, that people who think their car is in good shape develop major porblems anyway. I really depend on that thing.

I do tinker with cars a lot. I'll do major work when I have to. About half the time I create a lot of trouble for myself, but it get's fixed. I do anything that is easy, so as to avoid major work.