Editing Temperature Difference Sensor and Switch for Solar Water Circulation Pump
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The diodes form a H-bridge which drifts +- through to -+ across the op amp inputs, depending on the temperature difference which varies the diodes' forward resistance. I have been running this for seventeen years with the diode on the roof touching the hot water outlet pipe. | The diodes form a H-bridge which drifts +- through to -+ across the op amp inputs, depending on the temperature difference which varies the diodes' forward resistance. I have been running this for seventeen years with the diode on the roof touching the hot water outlet pipe. | ||
| + | This image is incorrect. Wait for update. May 7, 2022. | ||
[[File:Water_temp_difference_sensor_and-on-off-switch_for_solar-pump.png]] | [[File:Water_temp_difference_sensor_and-on-off-switch_for_solar-pump.png]] | ||
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Also, my pump can run without harm, at low voltages, and slower speed. So a sharp slope in the switching speed versus temperature change | Also, my pump can run without harm, at low voltages, and slower speed. So a sharp slope in the switching speed versus temperature change | ||
is not needed for my pump. A steeper slope and instantaneous off/on for some other pump might need some further thought, like perhaps | is not needed for my pump. A steeper slope and instantaneous off/on for some other pump might need some further thought, like perhaps | ||
| − | feedback-R6 should be much larger or omitted completely for more amplification. Experiment with it. | + | feedback-R6 should be much larger or omitted completely for more amplification. Experiment with it. |
| − | Alternative configuration with a relay: [[File:Water_temp_difference_sensor_and-on-off-switch_for_solar-pump_relay.png|200px|thumb|left| | + | Alternative configuration with a relay: [[File:Water_temp_difference_sensor_and-on-off-switch_for_solar-pump_relay.png|200px|thumb|left|alt text]] |
