Hi,
Lately I wanted to built a theremin, but since I'm quite an electronics noob I wanted to keep it very basic and use a 555 timer.
On the internet I read some articles in which LDR's were used, to influence the frequency of the 555 timer and therefor the sound produced by the speaker connected to the output.
I found this somewhat cheating, and wanted stay a bit closer to the original theremin, with which the position of your hand changes it's capacity finally resulting in a difference in tone. Instead of using LDR's I chose to use a normal resistor and replace the capacitor with a metal plate and my hand, serving as variable capacitor.
I tried a huge iron nail and later a small plate made of several sheets of aluminum. My hand would serve as the other part of the capacitor, also being connected to me, and therefor the ground.
This is the circuit used:
The capacitor is not connected to the 0V of the battery because the idea was that via your hand would also be the earth, this however did not work, even when putting out my shoes. Therefor I had to hold the 0V with my other hand.
Also strangely enough only a sound was created if I touched the sheet; applying more pressure did lower the frequentie, still I had to touch it.
I tried tuning it by using a variable resistor for R2 but no results; I still had to touch it.
The weird thing is that this circuit should only create an oscillating signal if a capacitor is present, but by touching both the ground and the sheet your body simply becomes part of the circuit as a resistor, and no other capacitors are present.
Can anyone explain why:
- I have to touch the 0V and my body does not ground itself
- Touching is needed to make this circuit work.
Thanks for your help.
Lately I wanted to built a theremin, but since I'm quite an electronics noob I wanted to keep it very basic and use a 555 timer.
On the internet I read some articles in which LDR's were used, to influence the frequency of the 555 timer and therefor the sound produced by the speaker connected to the output.
I found this somewhat cheating, and wanted stay a bit closer to the original theremin, with which the position of your hand changes it's capacity finally resulting in a difference in tone. Instead of using LDR's I chose to use a normal resistor and replace the capacitor with a metal plate and my hand, serving as variable capacitor.
I tried a huge iron nail and later a small plate made of several sheets of aluminum. My hand would serve as the other part of the capacitor, also being connected to me, and therefor the ground.
This is the circuit used:
The capacitor is not connected to the 0V of the battery because the idea was that via your hand would also be the earth, this however did not work, even when putting out my shoes. Therefor I had to hold the 0V with my other hand.
Also strangely enough only a sound was created if I touched the sheet; applying more pressure did lower the frequentie, still I had to touch it.
I tried tuning it by using a variable resistor for R2 but no results; I still had to touch it.
The weird thing is that this circuit should only create an oscillating signal if a capacitor is present, but by touching both the ground and the sheet your body simply becomes part of the circuit as a resistor, and no other capacitors are present.
Can anyone explain why:
- I have to touch the 0V and my body does not ground itself
- Touching is needed to make this circuit work.
Thanks for your help.
