OK, here's a clean a sheet of paper. I need a way to LOG a series of on on/off pulses, so that I have a record of time a circuit is "on" versus total time. Even better, I'd like to also log a DC voltage along with that. Essentially I need a strip chart recorder.
Here's the scenario: I've gotten a nice, thermostatically controlled cooler circuit working nicely. It gives me temperature control to within about 1°C by toggling a TEC on and off every few minutes. Now I need to start collecting data using my cooler, looking at how it responds to things going on inside of it. (Yes, it's being used as a calorimiter.) An ideal solution would be a strip chart recorder to record the sawtoothing temperature and also the square wave of voltage applied to the TEC. But I don't have a dual pen strip chart recorder and need to rig up a poor man's alternative. I DO have old computers lying around that could be put to the task, but they're not good with DC voltages. Sound yes, DC no.
Any cheap, simple ideas? Controlled stopwatches?
I should add that an observer with a clock and a multimeter is also a perfect solution. They could record temperature and on/off times by hand. But we're talking about experiments that will take hours, maybe 6-12 hours or more, so I need an automated solution.
Here's the scenario: I've gotten a nice, thermostatically controlled cooler circuit working nicely. It gives me temperature control to within about 1°C by toggling a TEC on and off every few minutes. Now I need to start collecting data using my cooler, looking at how it responds to things going on inside of it. (Yes, it's being used as a calorimiter.) An ideal solution would be a strip chart recorder to record the sawtoothing temperature and also the square wave of voltage applied to the TEC. But I don't have a dual pen strip chart recorder and need to rig up a poor man's alternative. I DO have old computers lying around that could be put to the task, but they're not good with DC voltages. Sound yes, DC no.
Any cheap, simple ideas? Controlled stopwatches?
I should add that an observer with a clock and a multimeter is also a perfect solution. They could record temperature and on/off times by hand. But we're talking about experiments that will take hours, maybe 6-12 hours or more, so I need an automated solution.
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