Low battery indicator circuits

[noveltone]

Great! Thanks for drafting this out.

 

[Avro_Arrow]

The resistors won't add noise, they are not in the signal path.
 
Quote:

Thanks for posting aos's design with additional notes.  I'd like to ask something. I had bought previously the parts required for Tangent/Hadron's circuit, and he's listing resistor values in excess of 100k.  Since I was going to use that circuit I'm resulting in R1 and R4 values of 470k and 511k (if R2 is 100k). Pretty high values and I'm concerned these will introduce needless noise to the Pimeta's power supply.  Aside from more current draw, is there any reason I can't tone those down to values more like those shown in aos'? 
 
Collin

 

[qusp]

Quote:

You pretty much need to design a circuit board for that, though. You also have to order the chip from the supplier. While you could just hack the analog circuit as well as buy parts in your local electronics store. And it is probably cheaper, too. I agree though, if I was designing something I'd probably use the chip like you mentioned. But if you are building somebody else's design it's much easier to add a small perfboard with a simple analog circuit than open Eagle, spend an hour in it and then wait 3 weeks for the boards to arrive (at high cost)...

agreed, not the sort of thing you would have just sitting in your parts bin,well unless you are me and you do need a PCB really, suppose you could get creative. PCBs are not so hard to do yourself these days though, but does require a new level of knowledge and skill. that said the app note circuit is pretty small and simple. I like your cct as well and would probably do something like that if I was as you say; adding it to an existing device.

 

[Avro_Arrow]

Here is a schematic I was messing with a few months ago...
I just thought I would post it for interests sake.
I think it had about 0.2mV of hysteresis.
You could sub the 7805 for any voltage reference.
 
Sorry for the TINA drafting...
 

 

[Reintz]

Avro_Arrow, thanks for the schematic at page 4. I changed the layout a bit and made myself an indicator pcb measuring 14,9x15,6mm (which is something like 0,587x0,614inch). It fits in my CMoy perfectly.
 
My CMoy before

 
and now

The smallest pcb is tle2426.

 

[Avro_Arrow]

Thanks Reintz.
Thanks also to aos for the original schematic.
 
Looks good, I'm putting one in my next amp also.

 

[holland]

Damn, that is a sexy little thing.  I wish I had the equipment to etch...

 

[Avro_Arrow]

Reintz got me thinking to try and make this smaller.
I switched to SMD 0805 resistors and SOT23 devices.
Here is the result. Same schematic as post #56.