LordSputnik
- Aug 11, 2011
- 45
- Joined
- Aug 11, 2011
- Messages
- 45
Hey everyone!
I've just finished the AQA Electronics A-Level course this year, and am hoping to start studying Electronic Engineering at Uni this September.
I've been looking for a project to do over the summer break, and decided to work on building a theremin. At this point, I realized how little electronics was actually in the A-Level! We had done quite a lot of DC circuit design, but next to nothing on AC theory and inductors in particular.
Since then, I've done quite a bit of research into AC stuff, but I have a few questions about the following circuit:
I've managed to work out that the subsystem in the top left is an oscillator, with the antenna functioning as a variable capacitor connected in parallel with the variable inductor, and I think I understand fairly well how it works. The block below that looks quite similar, so I'm assuming that's another oscillator. The bit on the bottom right looks like some sort of power amplifier, using the two JFETs.
As for the other parts, and how they all combine, I haven't a clue. I know theremins work using heterodyning to produce a new signal from a combination of signals, so I guess that the signal from the pitch oscillator is mixed with the signal from the fixed oscillator below it, to produce an audio frequency signal that's the difference between the two signals.
Could anyone explain how the volume control works, and give an overview of how the blocks fit together.
Many Thanks,
Ben
I've just finished the AQA Electronics A-Level course this year, and am hoping to start studying Electronic Engineering at Uni this September.
I've been looking for a project to do over the summer break, and decided to work on building a theremin. At this point, I realized how little electronics was actually in the A-Level! We had done quite a lot of DC circuit design, but next to nothing on AC theory and inductors in particular.
Since then, I've done quite a bit of research into AC stuff, but I have a few questions about the following circuit:
I've managed to work out that the subsystem in the top left is an oscillator, with the antenna functioning as a variable capacitor connected in parallel with the variable inductor, and I think I understand fairly well how it works. The block below that looks quite similar, so I'm assuming that's another oscillator. The bit on the bottom right looks like some sort of power amplifier, using the two JFETs.
As for the other parts, and how they all combine, I haven't a clue. I know theremins work using heterodyning to produce a new signal from a combination of signals, so I guess that the signal from the pitch oscillator is mixed with the signal from the fixed oscillator below it, to produce an audio frequency signal that's the difference between the two signals.
Could anyone explain how the volume control works, and give an overview of how the blocks fit together.
Many Thanks,
Ben
