Issue link: https://iconnect007.uberflip.com/i/1526666
86 PCB007 MAGAZINE I SEPTEMBER 2024 voltage amplifier for the 50 mV DC signal and a voltage-to-frequency converter to drive the totalizer. ey are also available for purchase from the major plating supply vendors, rang- ing from $450 to $800 based on features; those can include replenishment pumps. Amp-hour totalizers for pulse-plating power supplies are more complex and thus, more expensive. Spectrophotometers Spectrophotometers, like conductivity, are very popular in middle and high school sci- ence classes, especially for experiments involv- ing pollution. As such, there are several low- cost spectrophotometers that are in the public domain for schools to use. e most used is the LEGO spectrophotometer I previously talked about 1 . Controllers A controller is constructed by taking the out- put of the sensor or sensor electronics and com- paring it to the setpoint. e simplest control- ler is just a simple on/off relay, or it can be as complex as a PID controller that is much more expensive. ere are controller programs avail- able for all the popular "maker" microcomput- ers on the market, as well as simply writing your own. Below, I provide some information on microcomputers and programming that will allow for some effective DIY controllers. Microcomputers and PLCs Figure 6 illustrates four of the more popular maker or hobby microcomputers. e Arduino Uno, QuePython, Micro:bit and Raspberry Pi are all 32-bit computers with built-in network- Figure 6: Microcomputers and available software make DIY controllers now easier than ever. The Arduino Uno, QuePython, Micro:bit, and Raspberry Pi are all 32-bit computers with built-in networking features that are less than $78.