Hi all
I am working on a project and come up against a weid problem (which I have now engineered around)
My circuit runs off a 12 volt battery and I wanted some means of a battery low indicator (battery low goes to a uhf transmitter)
Ah ha, Easy I thought.
The circuit attached below is the part of my circuit that played up.
When I wired this up on strip board it seemed to go fine. When the pot divider network outputed below the zener reference the comparator outputed false and the 10k pullup resistor caused an output true and vise versa.
The only odd thing I noticed is that close to setpoint of the zener the output fluttered, the closer to setpoint the faster the flutter until at setpoint the output went solid (I had a led on the output)
So I set the pot up so the output was only just off and I disconnected the circuit and connected a 9v battery expecting it to output as a low battery..... but no go.
The pot votage divider network did its job but the zener voltage dropped off ( the 6 volt zener was doing 2.5 volts)
Can anybody suggest what might cause these sorts of weird problems. I have little experience with comparators and every time I use them there seems to be problems.
In the end I engineered aroung the problem by using a regulted 5volt rail in another part of the circuit as a reference and the circuit worked fine.
Thanks
Bruce
I am working on a project and come up against a weid problem (which I have now engineered around)
My circuit runs off a 12 volt battery and I wanted some means of a battery low indicator (battery low goes to a uhf transmitter)
Ah ha, Easy I thought.
The circuit attached below is the part of my circuit that played up.
When I wired this up on strip board it seemed to go fine. When the pot divider network outputed below the zener reference the comparator outputed false and the 10k pullup resistor caused an output true and vise versa.
The only odd thing I noticed is that close to setpoint of the zener the output fluttered, the closer to setpoint the faster the flutter until at setpoint the output went solid (I had a led on the output)
So I set the pot up so the output was only just off and I disconnected the circuit and connected a 9v battery expecting it to output as a low battery..... but no go.
The pot votage divider network did its job but the zener voltage dropped off ( the 6 volt zener was doing 2.5 volts)
Can anybody suggest what might cause these sorts of weird problems. I have little experience with comparators and every time I use them there seems to be problems.
In the end I engineered aroung the problem by using a regulted 5volt rail in another part of the circuit as a reference and the circuit worked fine.
Thanks
Bruce
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