Bought 4 micro servos that are used in RC airplanes (not high torque, just 9g). Buying a stepper motor next.

Today I am going to figure out how to use a 2.25 volt (actually hardly a voltage in indoor light) 100mA solar cell as a photoresistor light sensor so I can post another video and demo. I guess it will also be able to be made into a voltage meter.

Two Pinned Things As Sensors:

A microphone, speaker or even our piezo can be used as a sound detector, see this link. A LED can be made to detect darkness (not good for light differences, but can tell difference between day and night). A motor can be used to detect turning. Almost anything that generates or converts mechanical energy to electricity in any minor way (low voltages and milliamps) can be hacked as a sensor for an AVR project. Infared LED can be used for sensing walls and other obstacles.

Got a solar cell work as sensor (similar to a photodiode or phototransistor), but we are dealing with such low measurements with indoor lighting, that the noise/interference/EMF or whatever it is, is causing too much static and had to use another breadboard to take sensitive electronics away from the Atmega168 MCU (this helped lower interference greatly on a previous project involving a 3 pinned switch as input). Also by complete accident, wind up making a Theremin, a Geiger counter styled EMF detector and a funky noise maker (random beat/tone/beep, random timing/delay thingie) from same script (tweaked values) and same breadboard layout. See source code HERE for Geiger counter EMF detector (play around with tone frequency, remove/add delays) I will make a video this weekend.