- on Car and bicycle
- Published in issue 9/1981 on page 7
evolution counter elektor september 1981 â€” 9-07 revolution counter counts both up and down An up/down counter and two opto detectors with an LED display form a relatively easy to build and highly accurate counter. Since the cost of components is kept to an absolute minimum, the device rras infinite possibilities for hobbyists ranging from amateur sound technicians to photographers. Recently, a prototype model was exhibited at an electronics fair in Germany and was found to be surprisingly popular. 1 Judging by people"s reactions at the electronics fair, this revolution counter can serve a variety of purposes. One favourite "application" involves trying to "trick" the device into giving a wrong indication by simply turning it back- wards and forwards for a time. Readers are assured, however, that that gets to be pretty frustrating pastime after a while, for provided the counter is con- structed in the proper manner, it is very difficult to "lead it up the garden path". However sl...