BEAM Projects > Lil' Miller

Lil' Miller Bot

Lil' Miller Bot

Lil' Miller Circuit

Lil' Miller Circuit from
CostaRican Beam Site

Circuit used: Lil' Miller from CostaRican Beam Site

Behavior of Circuit: The solar cell charges the 3300uF capacitor and the photodiodes determines which motor fires. It charges and fires pretty quickly under a 60W bulb.


Construction Notes: Parts include: 3300uF capacitor, 3.5v Solar cell, .22uF Capacitor, 1N914 Diode (click link for datasheet), 2N3904 Transistor, and a 1381J (2.7v). I used a freeform layout, starting with the 2N3904s facing each other. As a rule of thumb, I try to use a 1381 variety that is 1v less than the voltage of the solar cell. My main goal was to fit everything under the solar cell. As you can see below, I did it. Once I completed the engine portion, I used a piece of square brass tube for the main part of the frame. With the motors soldered to it, the motors were at 90 degrees to each other. Testing revealed that them motors should be at a wider angle. I split the tube on the corner and pried the motors apart. I used a brass wire to support the solar cell from the rear and one of the transistor leads supporting it in the front.

It is quite active under a 60W bulb and tracks the light fairly well. I could have used a better photodiode, but these are adequate.

Check out the BEAM Gallery for larger pictures of the finished bot!

2N2904s with grounds attached

2N2904s with grounds attached

Goal Accomplished!

Goal Accomplished! Everything is under the solar cell.

Side view

Side View

Frame with Taildragger

Frame with Taildragger

Closeup of Taildragger

Closeup of Taildragger

Front View of the frame

Front View of the frame

Original Frame from rear

Original Frame from rear

Testing of Original Frame

Testing motor confguration

New angle on motors

New angle on motors

New angle on motors

Testing motor confguration

Side View of new motor angle

Side View of new motor angle

Finished Lil' Miller Bot

Finished Lil' Miller Bot

 

 

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