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This is a modification of 0.05.
I read up some more on the subject of analog closed
loops and realized I'd make a silly mistake; it's
not just speed that's a consideration, but gain as
well, and no matter how big I made the filter, it
still had massive gain. Dropping the 1M gain
limiting resistor should let it stabilize
properly. And it did. With the resistance at 10K instead of 1M, it slowly dropped from the maximum of 1.0A of current until there was just 0.65V across the power resistor, maintaining a constant temperature. Putting my finger on the thermistor caused it to increase power to compensate. Nice. Note that since the circuit is operating in linear mode, the power amplifiers dissipate a lot more heat. It absolutely requires a heatsink. Version 0.06 is the last breadboard version I will build. Stay tuned for construction of the insulated canister, and the permanent version of the circuit, v1.0. |