Small doodad; charge CR2032?

[mister_rf]

Here is a video of the tested circuit: :-D

 

[D.A.(Tony)Stewart]

nice video , I like the cap mount on the coin cell.

 

[mister_rf]

That’s a 22pF battery clip… ;-)

 

[Eudoxus]

The transistors are actually BC847s.


I decided to make a Mk.II that would detect out of spec voltage, not just no voltage; Mk.I doesn't trigger until <=0.5V on the +12V.

So Mk.II uses a comparator:

I could also substitute the LM321s for a single LM393, depending on what I get my hands on first.

If +12V is at ~11.4V-12.6V then green LED is on, no sound. If +12V goes over 12.6V or under 11.4V then green LED is on, red LED is on, and speaker beeps. If +12V goes below ~3.5V the comparator ceases functioning; output is the same. If +12V goes below ~2V the green LED turns off.

What do you think?

 

[mister_rf]

Well… To make it simple you have to complicate it first. :smile:
The circuit I have proposed start triggering alarm for a low voltage up to 10.6-10.8V (the 9V1 zener diode included ) and may keep the battery life for years. Now by changing to any active circuit you need to supply a constant current, and let’s suppose you can make supplementary adjustments in order to power up the circuit from the monitoring +5V/+12V power supply saving battery life, still remain to debate one question, does it worth it? :roll:
How many times the power supply will increase over the 12.6V? How many times this will fall and remain steady below the 11.4V value? Did you need all those indications?
If the answers is yes, then go for it…