Own-built Theremin hums

[i]"Just Pins 13, 11 and 9 should be connected to V+ and not number 10? What about number 14, which is shown connected in the circuit?" - Clemfon [/i]

OMG!

1.) Download data sheets for the 4069 and the 4046 IC's.

2.) Take some time to understand the basics (like which pins are the supply pins for these IC's)

The answer is.. Pin 14 on the 4069 is the +V supply pin.. If you do not connect this, it is possible that the IC will work because +V will be coupled through the input protection diodes - but it wont work well..

And I am sure you dont understand a word of the above anyway! ;-)

Replace the 4069, no reason to believe there will be damage to other.

100n capacitor connected across supply pins of each IC - (pins VDD and VSS) with as little wire / track as possible.

Sorry to be so sarky - but you wouldnt try to build (let alone present a thesis on) a car if you didnt know how to change a flat tyre..

You should (I feel) at least get a tiny bit of knowledge about electronics before trying to build a theremin!

Fred.

Yeah, you're right, I dont't know many of the electronic basics.

We just had to take part of this competition and our teacher "talked us into" bulding a theremin.
We thought, that we could just solder it and then it'll work, but it seems to be more complicated :)
Sure, we will take a look at the datasheets.

But anyway, thank you for your patient help!

Edit:

I see, Pin 10 is output, you were totally right. We should have taken a look to those sheets before soldering.

But would you be so kind to describe the position of the capacitors for the IC's, that you mentioned?

[i]"We just had to take part of this competition and our teacher "talked us into" bulding a theremin."[/i]

Sorry - Teachers like that should be made to do something equally unreasonable!

I have added some more answers to my last posting above. I really hope you get your circuit to work, But please - dont let this simple circuit be what you use to form an opinion about theremins on - Theremins are wonderful musical instruments - you are making a circuit which squeeks as you approach it!

Fred.

Hello again,

we've tried your solution, but it didn't work.
We connected Pin 9 and we disconnected Pin 10, as you said.

Does anyone have another idea?

You have still the option to send me the circuit board in order to get it fixed. Diagnosing at distance is difficult, connecting my oscilloscope and a frequency counter will allow me to find the problem within seconds...

"we've tried your solution, but it didn't work."

Then there is an additional fault - One thing is absolutely certain.. With the output of a gate tied to rail, it could not work!

This circuit is about as simple as electronics gets! With a logic probe (buy or borrow a CMOS logic probe if you have no test equipment) you need to check that the circuits are oscillating.. With a multimeter you need to check supplies etc.. Are you getting a supply on the IC power pins? - It is possible that you burned out a resistor (there was, if I remember, a resistor in the +V supply - I cant be bothered to check) when the output was shorted to the supply.. But it is unlikely.. one usually smells it cooking and sees smoke.

But - Whatever you do.. DONT put the circuit back the way it was! I assure you, there was no error on my part - NO output pin must EVER connect directly to a supply rail!

Thierry says: "connecting my oscilloscope and a frequency counter will allow me to find the problem within seconds"

And he will! I recomend you do this!

- But you will learn more by getting a few pieces of test kit from somewhere and exploring the circuit.

Fred.

In case my contact parameters were needed:

email: theremin(at)tfrenkel(dot)com
cell phone: plus-three-three-six-seven-five-eight-two-eight-zero-one-four
(most times the answering machine will respond when I'm unable to identify the caller. Leave a message - I'll call back)

I speak French, German and English
I understand Italian, Russian and Dutch if spoken slowly or written
I understand most biblical Hebrew and Latin if written

So don't hesitate to ask for help...