Friday, 28 April 2017

Carlsbro Suzz / Wah-Wah teardown / minor repair

I recently stumbled on an old Carlsbro suzz / wah-wah guitar effect pedal that I was given at some point in the 1990s. A quick google revealed it doesn't appear to be a particularly common pedal but interestingly it appears the two halves were available as individual pedals and there is a touch more information about them. Anyway, here is my two-in-one.

Thursday, 27 April 2017

H bridges, minor failure and troubleshooting

When I left off last time, I was raring to go with some sample PID code that allowed me to test out a basic movement between two points. I realised I hadn't included any wiring, and that's important for this post. Suffice to say, the code didn't work quite as I had intended, but not for obvious reasons. By that, I mean I spent hours trying to debug what was going on without success. Instead, I had to break out the oscilloscope and measure to find out what was really happening.

Wednesday, 26 April 2017

Motion control - H bridges and movement

In my last post I was talking about getting the feedback mechanism from a printhead carriage up and working. This enabled me to track how much relative movement of the carriage had occurred, but didn't enable me to make the thing move! That comes in this part. In order to get motion happening, I need something that can handle the voltages/currents the motor needs - a job for an H bridge!

Monday, 24 April 2017

Arduino, Motion Control and Encoders

I took a failed Canon Pixma all-in-one inkjet apart in order to see how it was engineered. I also extracted some of the mechanics so I could learn a bit more about motion control in the real world. This post is about that exploration. I was primarily interested in the printhead carriage, as it has a feedback loop to provide information back about the speed of the carriage and which direction it is travelling in.

The printhead carriage itself is little more than some mechanics in the form of a sliding assembly that holds the printhead, a DC motor driving a belt, an optical strip and a pair of optical sensors and an LED.