PicAxe Projects > PicAxe-08M Servo Controller V1

Finished PicAxe 08M Servo Controller V1

Finished Servo Controller

MicroWalker Schematic

PicAxe 08M Servo Controller inspired by TrainElectronics

Circuit used: It was largely taken from TrainElectronics.com. I drew it up in DipTrace (you can download the Diptrace files here). I have since decided to work on a version 2 of this project powered by a wall wart and two more standard potentiometers (I had to actually make the patterns for Diptrace).

Parts List: PicAxe-08M, 8-Pin DIP socket, 2 10K resistors, 1 22K resistor, 2 3-pin headers, and 1 2-pin header, 2 potentiometers (I used 47K, but you may use a larger value), and circuit board.

Construction Notes: The only real problem I ran it to was finding a pattern for the potentiometers. There wasn't anything in Diptrace. Fortunately, it is relatively easy to make a pattern. But I didn't think to enlarge the pads for my toner transfer method. Once I drilled the board, there wasn't much copper left AND I realized too late that I had mirrored it before printing (print the bottom as is, mirror the top). I should have re-read my TT Methodbefore starting!

I realized after I had populated the board that I should have marked the board better (programming and servo headers). This will be fixed on version 2.

I used a previous project the 5-Volt Power Supply to power it. Since it is a really small servo, it works ok. However, for version 2 I am going to use a wallwart so that I can use a larger servo. The programming cable is a db9 female connector and a 3-pin plug recycled from a computer fan. You only need pins 2, 3, and 5. I hook that up to my USB serial adapter and it works great.

Programming: You can get the programs from the TrainElectronics web site, or from here.

Adjusting: Turn the Start potentiometer that is connected to pin 1 of the PicAxe (CCW in the program), to the positive terminal. Turn the Range potentiometer, to its negative terminal. This sets the servo to start at its leftmost position and rotate to its maximum range. Adjusting the two pots will give control over the starting and ending point of the servo.

Stand by for version 2. It will have an on board 5V power regulator and better silk screen markings.

Problem with pads
This board's pads for the potentiometers are too small (far right side). AND I mirrorred it before printing.
New Pads
New pads, on the correct side (left)!
New pads etched
After Etching
Silk Screen on Top
Top Silk Screen - I put it on BEFORE drilling
Populated Board

Populated board.
Completed Project
Completed Project with programming cable

 

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