“Speed up the etching of printed circuit boards with an easy to build agitator.
I make a lot of my own printed circuit boards and etching was always a bit of a chore since you really need to keep the acid moving over the copper. My left arm muscle is now testament to the number of boards I have made over the years by manually agitating the acid bath.
I was watching a agitator built by TechBuilder on YouTube and decided I needed one.
Hardware
The unit is built around a Jiffy Box (157x95x53mm). The motor is a 100RPM geared 12V brushless motor from eBay. The hinge was one I had found in my toolbox (I think I got from Bunnings but can’t really remember. Anyway it’s a Black Nylon Hinge (48mm length x 48mm (open) x 9mm thick). The 3D printed Cam is held on to the motor shaft using a M3 grub screw and M3 nut. The bar incorporates two 3x8x3 bearings to reduce the friction.
Electronics
The motor speed is controlled using a PWM signal generated from a 555 timer via a N-Channel MOSFET. I used the same circuit that I designed for my Ender 5 light bar. Instead of driving an array of LEDs, it drives the motor. The other side of the motor is connected to VCC or 12V. You need to add a diode across the motor to stop back EMF from the motor destroying the MOSFET. (Anode to the MOSFET, Cathode to VCC). Also you need to replace R2 with a 0 ohm resistor.”