Review on ⏲️ MakerHawk Time Delay Relay: 12V 5V USB Controller Board with LCD Display for Delay-Off Timer Control Switch by Jim Booth

Our on top microwave oven has an exhaust fan that extends through an excessively long duct to an outside wall. We added an optional external wall fan, but the microwave fan switch wasn't available and I didn't want to manually turn the external fan on and off. To handle the switch we installed a 110VAC pressure switch on the duct with the idea that the increased pressure would turn on the external fan when the microwave exhaust fan was turned on. What actually happened was that the external fan would quickly depressurize and shut down, and the fan would cycle on and off every one to two seconds. Since the external fan is more powerful than the microwave fan, there was no way to fix the problem by adjusting the pressure setting. Instead I added this little time delay relay board which is powered by a little 12VDC LED transformer (YAYZA! IP44 12V 1.25A 15W Low Voltage Switching Power Supply for LEDs). I went with a low voltage relay and circuit as I figured it would be safer than 110VAC to connect to the pressure switch. I installed the transformer and circuit board (using the included plastic standoffs sandwiched between two pieces of Formica laminate glued together) in a 3 gang box with a separate adjacent accessory box for most AC connections. (Mounting details are available on request.) I set the delay to 10 minutes so now the external fan comes on when the microwave hood is turned on and runs for 10 minutes whether the microwave hood fan is running or not. When the microwave fan is on, the external fan will turn off for a second or two and restart for another 10 minutes. This seems like a much better solution for controlling an external exhaust fan than what we had before and the only problem is that I would like to see the digital countdown of seconds when it is running (but maybe in a few years I will overcome protocol). Months). Instructions were included with the board, and the settings were easy to work out on the test bench.