Building a pulse counter on the cheap


Josh of imsolidstate needed to reverse engineer a stepper motor on a linear actuator that he was repairing, so he built this 9-digit pulse counter to keep track of how the motor was being controlled. It’s a pretty standard circuit, however his build is exceptionally well put together. He claims that the whole thing cost less than $20 to build:

Recently I was fixing a piece of equipment and wanted a pulse counter to verify a stepper motor system. The existing linear slide was failing, but had a non-standard TPI. The step output was already programmed into a PLC. I had a programmable motor drive, but needed to know how many steps were commanded for a given linear move so I could electronically gear the system to a new linear slide.

That’s when I found the MC14453 3-digit BCD counter from ON semiconductor. ON semi has integrated three decade counters with an oscillator that multiplexes the 3 digits of an LED display. You pair it with an MC14543 7-segment decoder to have a three segment counter. You can cascade as many of these two chips as necessary by using the overflow output to clock the next stage, and feeding the first scan clock to the next multiplexer. I made a 9-digit counter, but you can do any multiple of three.

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