Handy timer module

[Bluejets]

Thought they might be of interest to some @ 5 for $1.00

https://www.ebay.com.au/itm/5Pcs-Mu...876744?hash=item2cad1c5748:g:SiwAAOSwMHdXSJlS

 

[BobK]

Now, if only we could interpret this means:

Available resistance adjusting timing, there are 8 * N (N = 0.1.2.3) times the timing selection,
time can be adjusted from 2s-1000h.

The chart they have for resistance vs, delay (which is dependent on supply voltage!) shows it going only from about 5 seconds to about 7000 seconds, which is a far cry from 1000h. Perhaps chaining them for the longer delays?

It looks to be an RC oscillator + counter, but the charts do not make sense that way. The frequency times the delay should come out to a constant, but they do not.

Bob

 

[AnalogKid]

In a standard 2-tranistor multivibrator, the frequency *is* dependent on the operating voltage. As the timing capacitor charges up from below GND, the transition level is not GND. it is one Vbe above GND. As the operating voltage decreases, the constant Vbe becomes a larger and larger percentage of the voltage swing across the timing capacitor, directly affecting the operating frequency. This is what the genius of the 555 avoided.

ak