Using something it was not originally intended for!

[Mike_K]

A friend from my club got a second-hand large-scale Spitfire (90" span) with homemade retracts based on a geared 280 motor with screw thread and limit switches on either end for up and down. The controllers it came with were shot, so he asked if I could do something.

I had previously programmed a retract controller for Tobe, so I thought I'd use a pair of Tobe's servo amp boards with a DRV8838 on board and that program. Alas, the DRV8838 kept cutting out on over-current protection, so I had to think again. I was just about to fire up KiCAD and design a new board when I remembered I'd been given a pair of Martin's GG recoder boards (I think he called them Ceptimus ATtiny85 Pulser) with an ATtiny85 and a Toshiba TB6612FNG motor driver, Martin had paralleled up the dual outputs, doubling its current rating. A quick change of code to allow for the different processor and motor controller and bingo, it worked first-time

So even though you didn't even know about them, thanks Martin for a nice pair of retract controllers!

Mike

PS I also programmed the two controllers slightly differently as the full size has one gear slightly delayed to the other and used pwm so they retract at the same speed as a full size.