BEAM Projects > MicroCrawler

Finished MicroWalker

Finished MicroWalker

MicroWalker Schematic

MicroCrawler Schematic from CostaRicaBEAM

Circuit used: The MicroCrawler CostaRican Beam Site. The circuit was originally designed by Wilf. A really good write up on the circuit can be found at Solarbotics.net.

Behavior of Circuit: Once built, I will write up what I observe.

Construction Notes: Parts include: 74AC240, a modified servo, 2-photodiodes, 1000uf capacitor, .33uF capacitor, 2M resistor, 2-5.1M resistors, and a 4.5V battery. I etched the PCB using the same method in my Making PCBs with Toner Transfer.

I installed subsitutes for the photos here. I have .33uf capacitors, 5.1M resistors, and 2M resistors on order. I will detail the rest of the build and will have to wait until I get the parts in. But until then Enjoy!

To modify the servo: Unsolder all of the wires inside the servo. There are 3 to the circuit board and two to the motor. I then unsoldered the potentiometer (3 connections). Re-solder the 3 wire lead to the potentiometer. Add two wires for the motor. I ran the wires out along side the potentiometer wires (see the pictures below).

This was a fun project. After replacing the placeholder componets (3 resistors and a capacitor), it worked the first time! It turned out that the hardest part was adjusting the crawl of the servo. If you look closely at the front picture, you will see two brass wires that go up on either side of the servo to limit the motion. That and some judicious bending of the legs got it crawling and looking for light.

Etched board
Etched board
Silk side of board
Silk side of board
MicroCrawler in Work
MicroCrawler in Work
Front of MicroCrawler
Front of MicroCrawler
Top of MicroCrawler
Top of MicroCrawler
Bottom of MicroCrawler
Bottom of MicroCrawler

 

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