Thierymin pitch only theremin giving nothing but static an high pitched noises.

Thaddeus said: "Are the parasitic capacitances really high enough to stop it functioning all together?"

Is it working for you?    Oscillators are very finicky, like a cat!

This is dewster at his day job

Christopher

Ouch. Fair point. So should I buy someboard I can carve a layout into?

Thaddeus go back and read the last paragraph in the very first Thierrymin post.

In the beginning

For all my projects I furnished an iron on PDF copper pattern so builders could make their own accurate circuit board. This is a skill I think every budding engineer should learn. I did this for one of dewster's best designs and maybe Thierry has it for his design. I have too many irons in the fire (lazy) to draw this up for you currently.  Order a commercially made pc board from Thierry, the learning curve is making this project more difficult than it needs to be for you.

Christopher

Okay, thank you very much, I'll work on this, and once I've got it all etched on board, and I still can't make it work, I'll send you a message.

"Christopher said it won't work on bread board? Are the parasitc capacitances really high enough to stop it functioning all together?"  - Thaddeus

I test high frequency Theremin oscillators (~2MHz, roughly 10x "normal" pitch Theremin oscillator freqs) all the time on my breadboard and they work fine, though they will likely behave a bit differently on a dedicated PWB.  Parasitics likely throw off the frequency some, and if it's too much to adjust then that could be a problem.  But it will almost certainly oscillate if you are even half-way careful with layout.  I suppose this is one of those "you have to know how to play the game before you break the rules" things, but it isn't nearly as dire as many describe IMO.  My advice is to get that scope and see what's going on before you make your next move.  Without a scope you're just feeling your way in the dark, PWB or no PWB.

Check the pinout of the FETs you are using.  There are two types of pinouts, one places the gate in the middle, the other places the gate on an outer pin.

The null point / audio heterodyning zone can often be squirrely, and easy to miss when adjusting things.

Alright. I shall halt where I am untill I can look at it in a scope. I'm 100% sure I have the right things going into the right pins. I've made very sure of that.

I see... intresting. I have achieved sound!!! But the range is very low and high pitched. But it is working.

You should understand that the capacitive effect of the hand on the pitch antenna is only between < 0.01pF at 60cm and about 1.3pF at 1cm. Thus every other electrical conductor near the antenna will reduce the effect of the hand. That's why theremins normally have housings which are not conductive (plastic or wood), the circuit board layout is optimized for minimum parasitic capacitance, the instrument has to be set up on top of a microphone stand and has to have a free space with a radius of 1,5m around it, all that to reduce external capacitive effects.

For this particular Thierrymin circuit, it is also important to respect the given dimensions for the pitch antenna (a thinner or shorter antenna will not have enough capacitive effect and a thicker and longer one will have too much static capacitance) and to mount the latter at a distance of >= 10cm away from the circuit board, separated and supported by non conductive material.

Thank you Thiery I shall try all of the above.

...and don't forget to tune the circuit correctly as written in the circuit description