The honorable relay vs technology
Posted: Tue Jul 02, 2019 8:05 pm
We have a console dehumidifier in the basement of our house. We also have two new cats...! Their litter box is in the basement. The cat's don't like, and are scared of, the dehumidifier. ....Are you getting the picture yet?
To keep peace it was decided to let the humidifier run all day, since cats tend to sleep most of the day time, and around midnight shut the dehumidifier off for several hours to give them, and us, a much needed break.
So since nobody remembers things like turning stuff on and off, a timer was to be the answer. The dehumidifier does have a timer but it only offers a delay start or timed run time but does not cycle.
An external timer was connected to the power and here comes the technology part... It didn't work. Oh the dehumidifier came on, it's internal computer initialized and then it went to sleep, waiting for a finger push on the on/off button. Holding the button down while powering it up did nothing different.
The solution was to box up a line voltage relay to be operated by the timer and then connect it's contacts to the keyboard switch in the dehumidifier. A pound of screws and half the tools I own later the PCB was out, the wires were soldered, and the out of warranty unit was reassembled.
Since the on/off switch needs to be cycled I set the timer to go on at 12:00AM then off at 12:01 then on again at 06:00 AM and off at 06:01. So, the relay is energized twice a day for one minute each time. Understand that the switch is momentary switch, press on-press off so every press alternates the run/stop. The external timer doesn't know, or does it care a whit , if the dehumidifier is running or not, it just makes and breaks it's relay contacts twice a day.
So, unless someone operates the power switch on the dehumidifier all should be well. If they do, then the timer won't know it, the on/off times will be reversed, and the cats will probably have a really bad day!
To keep peace it was decided to let the humidifier run all day, since cats tend to sleep most of the day time, and around midnight shut the dehumidifier off for several hours to give them, and us, a much needed break.
So since nobody remembers things like turning stuff on and off, a timer was to be the answer. The dehumidifier does have a timer but it only offers a delay start or timed run time but does not cycle.
An external timer was connected to the power and here comes the technology part... It didn't work. Oh the dehumidifier came on, it's internal computer initialized and then it went to sleep, waiting for a finger push on the on/off button. Holding the button down while powering it up did nothing different.
The solution was to box up a line voltage relay to be operated by the timer and then connect it's contacts to the keyboard switch in the dehumidifier. A pound of screws and half the tools I own later the PCB was out, the wires were soldered, and the out of warranty unit was reassembled.
Since the on/off switch needs to be cycled I set the timer to go on at 12:00AM then off at 12:01 then on again at 06:00 AM and off at 06:01. So, the relay is energized twice a day for one minute each time. Understand that the switch is momentary switch, press on-press off so every press alternates the run/stop. The external timer doesn't know, or does it care a whit , if the dehumidifier is running or not, it just makes and breaks it's relay contacts twice a day.
So, unless someone operates the power switch on the dehumidifier all should be well. If they do, then the timer won't know it, the on/off times will be reversed, and the cats will probably have a really bad day!