Drawdio as a voltage or current sensor...

[ribo]

Trying to hack the Drawdio into a voltage or current sensor for a school project. Drawdio seems to be a high resistance sensor (body resistance) with pitch linked to resistance or current in the circuit. I'm making a solar PV demonstrator that will have an LED display to show the current produced when a small PV panel is pointed at the sun (current is proportional to irradiance). I'd also like to add a feature using sound pitch to indicate current in the circuit so that when kids point the small panel at the ground it makes a low sound and when pointed at the sun it screeches a high pitched sound. The panel will be at about 12V, 1amp if in short circuit mode and in full sun.

Any ideas?

-Ribo

[Zener]

You are asking for a Voltage Controlled Oscillator. It can be made out of a 555 like the Drawdio is but the wiring is a little different. Here is one of many hits I found when I searched for "555 VCO circuit".

http://ecelab.com/circuit-vco-555.htm

You may find the high/low pitch reveresed from what you want, depending on the ciruit. Or it may be exactly as you want.

[ribo]

thanks for the tip -- will play around with my un-assembled drawdio kit on a breadboard to see what i can do and post back.

[ribo]

Making the perfect 555 circuit for this was way too much hassle. I bought an Arduino and used the map function with a speaker tone output and it works great with all the flexibility I need and even some other LED indicator options.