Log Pump

Cool.. any idea how it works or where it's used? I assume as part of an analog computer or signal processor.

Hi J. Thanks. Actually it's used in radiation detection equipment. The input (or logic in this case) is detected by a Geiger-Mueller tube. The analog output (which would be the ammeter here) drives a 0-50uA meter.

I meant to add this initially. This is not my design. I am here for learning purposes only.

Oh interesting. I actually had no idea. That makes perfect sense though since I'd imagine the intensity of radiation might span several orders of magnitude in a high radiation environment. What are each of the pots for?

Hi again! Thanks for your question. The simple answer... calibration of the device at a given constant. Keep in mind that this is only a very small part of a much larger picture. So the meter that is being driven here is expressed in milliREM/hr - 0.1 thru 1000. There is a formula for conversion of mR/hr to CPM (counts per minute) to Hz. An 8Vdc pulse generator is used as the calibration constant, at 14Hz, 140Hz, and 1.4KHz; which are, respectively, 10mR/hr, 100mR/hr, and 1000mR/hr. Unfortunately, the pulse train within this app does not allow manipulation of the amplitude, and my math is not so great anymore. The first pot is used to set the RC time constant within the log pump, and has minimal effect on the output. The next one is used to set the feedback gain to the flip-flop to minimize noise. The other two are for different elements downstream I believe, although I'd have to double check my answer later. Thanks again!!