Great site, seems to be a bunch of good people on allaboutcircuits. I've been reading here for a while now, and I recently joined. I am a newby, this is my first post.
I need to build a controller to control the fan motor inside an upright, frost free freezer. The OEM design energizes the fan whenever the compressor is energized: compressor on, fan on; compressor off, fan off. I need additional functionality.
The fan controller shall have 2 modes of operation, manual and automatic, switched by a 2 position toggle. In manual mode, the fan shall run continuously. In automatic mode, the controller must perform 2 types of fan control: a timer, and a delay timer. The timer shall control the fan on and off time intervals whenever the compressor is not energized. On will range from 1 to 10 minutes, off will range from 10 to 60 minutes. I currently expect to converge on a 1-5 minutes on, 20-30 minutes off type cycle, following trials and data analysis. The delay timer shall delay the de-energizing of the fan after the compressor de-energizes: the compressor kicks out, the fan continues to run for (time value) minutes. The time window will range from 1 to 10 minutes. I expect to converge on a ~ 5 minute time window, following trials and data analysis. If any of these time windows add large complexity or cost to the circuit, I can specify narrower windows.
Both the fan and compressor operate on standard 120V AC. Anytime the compressor is running, the fan must run. The signal that the compressor is/is not running shall be the 120V that energizes the compressor. I will have to access the fan motor to determine the wattage it pulls. I Google’d a replacement fan motor, the picture had 7.7W printed on the motor winding wrap.
So, with the toggle switch in manual mode, the fan runs continuously, no matter what the thermostat, compressor, timer, or delay timer say or do. The only way the fan de-energizes is by unplugging the freezer. With the toggle switch in Automatic mode, the timer runs the fan for XX minutes, turns it off for YY minutes, cycles this way infinitely. No matter where the timer is in its cycle, if the compressor kicks in, the fan runs the entire time that the compressor is energized, and then continues to run for ZZ minutes after the thermostat drops the compressor, as per the delay timer.
Example of Automatic mode operation: (and this is what I currently think the final time values will be close to).
Example time values:
Fan on time value: "XX" = 2 min
Fan off time value: "YY" = 20 min
Fan delay-on-drop time value: "ZZ" = 5 min
The example starts when the freezer thermostat engages the compressor; the controller simultaneously turns the fan on. The compressor runs until it reaches thermostat set point and then cuts out. The delay timer in the controller keeps the fan running for 5 more minutes, at which time the controller cuts power to the fan and the timer in the controller starts counting off 20 min. At the end of 20 min, the controller turns on the fan and it runs for 2 minutes, this 2 on 20 off cycle continues till the thermostat engages the compressor again. (Note: I would prefer the fan timer to start its fan off (YY) timer count when the compressor kicks out (de-energizes). If that complicates the circuit, start the YY count at the end of the ZZ count. Either works.)
I have been researching how to build this controller for a few weeks, and I have some ideas, but I am not an electronics guy, my skills are in the mechanical realm. I can solder, read a wiring diagram (12V and 120/240V), etc. I built a digital clock for a digital devices class many years ago. I am very good at automotive wiring diagnosis and repair. I repair most things around my home.
I do not have a circuit diagram for this controller. If practical, I would like to build the controller with devices that allow for adjusting the 3 time values.
Any and all help is greatly appreciated.
I need to build a controller to control the fan motor inside an upright, frost free freezer. The OEM design energizes the fan whenever the compressor is energized: compressor on, fan on; compressor off, fan off. I need additional functionality.
The fan controller shall have 2 modes of operation, manual and automatic, switched by a 2 position toggle. In manual mode, the fan shall run continuously. In automatic mode, the controller must perform 2 types of fan control: a timer, and a delay timer. The timer shall control the fan on and off time intervals whenever the compressor is not energized. On will range from 1 to 10 minutes, off will range from 10 to 60 minutes. I currently expect to converge on a 1-5 minutes on, 20-30 minutes off type cycle, following trials and data analysis. The delay timer shall delay the de-energizing of the fan after the compressor de-energizes: the compressor kicks out, the fan continues to run for (time value) minutes. The time window will range from 1 to 10 minutes. I expect to converge on a ~ 5 minute time window, following trials and data analysis. If any of these time windows add large complexity or cost to the circuit, I can specify narrower windows.
Both the fan and compressor operate on standard 120V AC. Anytime the compressor is running, the fan must run. The signal that the compressor is/is not running shall be the 120V that energizes the compressor. I will have to access the fan motor to determine the wattage it pulls. I Google’d a replacement fan motor, the picture had 7.7W printed on the motor winding wrap.
So, with the toggle switch in manual mode, the fan runs continuously, no matter what the thermostat, compressor, timer, or delay timer say or do. The only way the fan de-energizes is by unplugging the freezer. With the toggle switch in Automatic mode, the timer runs the fan for XX minutes, turns it off for YY minutes, cycles this way infinitely. No matter where the timer is in its cycle, if the compressor kicks in, the fan runs the entire time that the compressor is energized, and then continues to run for ZZ minutes after the thermostat drops the compressor, as per the delay timer.
Example of Automatic mode operation: (and this is what I currently think the final time values will be close to).
Example time values:
Fan on time value: "XX" = 2 min
Fan off time value: "YY" = 20 min
Fan delay-on-drop time value: "ZZ" = 5 min
The example starts when the freezer thermostat engages the compressor; the controller simultaneously turns the fan on. The compressor runs until it reaches thermostat set point and then cuts out. The delay timer in the controller keeps the fan running for 5 more minutes, at which time the controller cuts power to the fan and the timer in the controller starts counting off 20 min. At the end of 20 min, the controller turns on the fan and it runs for 2 minutes, this 2 on 20 off cycle continues till the thermostat engages the compressor again. (Note: I would prefer the fan timer to start its fan off (YY) timer count when the compressor kicks out (de-energizes). If that complicates the circuit, start the YY count at the end of the ZZ count. Either works.)
I have been researching how to build this controller for a few weeks, and I have some ideas, but I am not an electronics guy, my skills are in the mechanical realm. I can solder, read a wiring diagram (12V and 120/240V), etc. I built a digital clock for a digital devices class many years ago. I am very good at automotive wiring diagnosis and repair. I repair most things around my home.
I do not have a circuit diagram for this controller. If practical, I would like to build the controller with devices that allow for adjusting the 3 time values.
Any and all help is greatly appreciated.
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