Designing 555 based musical body keyboard wrist mounted instrument

[jpoopdog]

Hi,

Recently i had two pretty cool ideas, after seeing that the sound hack contest was open on instructables.
The first was a touch wire keyboard, essentially consisting of a wire used one way or another, to alter the frequency of a 555 timer, to give a single matrix keyboard effect, i was inspired by this idea after finding an amusing 555 based pcb keyboard kit, though already built, in which you could use a grounding wire on each pcb printed key, to play various tones through 555 timers set up to sound like organs. i then discovered though that i could play the keyboard simply by holding the probe in the same hand, and using my fingers instead.


This inspired me to try out something, a wrist mounted oscillator, which plays a tone based on body resistance!
essentially, it would have a contact touching ones wrist, and another on the persons fingertips, and from there depending on the resistance between the wrist and the contacted area of the body, it would play a specific tone. Two used in conjunction with one another , along with resistors on each fingertip, could actually create something capable of playing basic music.


What i wanted to ask however was, the viability of this idea?

Would a 555 timer be capable of changing the frequency based on the bodies resistances, or would i need to use something a little different, that utilizes high voltages to test resistance?

What would i need in order to get this device to function? but everything being entirely on the wrist and hand and nowhere else?

 

[Mr RB]

As a concept it should work fine.

Designing it will be a bit harder. Since you want to change the note (freq) based on body resistance, you first need to change the body resistance to a voltage (which you can do with a voltage divider, one fixed resistor:body resistance.

Then you need a voltage to frequency converter, so a 555 might not be the best choice.

Also, you need a way to stop the note from playing when the body resistance is infinite (skin not touched).

 

[dougy83]

Designing it will be a bit harder. Since you want to change the note (freq) based on body resistance, you first need to change the body resistance to a voltage (which you can do with a voltage divider, one fixed resistor:body resistance.

You can use the skin resistance as the timing resistor in the 555 circuit; there's no need to convert to voltage, etc.

Here's some similar ideas:
https://learn.adafruit.com/drawdio

https://rimstar.org/science_electronics_projects/555_timer_music_instrument.htm

 

[audioguru]

The output of a 555 is a fixed squarewave that sounds like a buzzer, not like a musical instrument.
The resistance of your body continuously changes when the temperature changes and when your mood changes. Then the frequency of the 555 oscillator will change all over the place.

Instead, why not make a Theremin that changes its frequency (and maybe changes its volume) by the distance of your hands to its antennas??

 

[Mr RB]

You can use the skin resistance as the timing resistor in the 555 circuit; there's no need to convert to voltage, etc.
...

Nice one! Thanks.