I was thinking it would be nice to add voltage indicator to a headlamp I’m building but I lack the skills to make one my self. I was wondering are there voltage indicator circuits (like drivers) for sale?
I know there are small 3 digit voltmeters on ebay, dx… but they are too big. Ideally I’d like a circuit for a multicolor led - green when full, red when half depleted, blinking red when almost empty (single li-on cell)
You may be able to get something similar to this on ebay:
One reviewer said it works like this:
“Above 3.7V, solid blue Below 3.7V, blue blinking Below 3.2V red light and beep Below 3v solid red and long beep”
Spacing of the color settings is not ideal though, would be better when the blinking started at 3.9 to 4.0 V , which is closer to 50 % discharge.
You might want to get rid of the little speaker, unless you want to have acoustic feedback too ;).
I like your headlamp, especially the ‘industrial’, no nonsense look of it.
That looks promising! Thank you!
Beeper will definitely have to go off.
Any Idea how big is the board?
How about this
I assume the two pin plug is standard size for RC LiPo packs, so I measured the board from screen and i estimate 13mm x 23 mm, give or take (without the black beeper thing).
I have to apologize, when I posted this I did not realize this item is currently sold out at hobby king.
But that unit charlestt posted is awesome! Thanks for the link, I’m totally getting one of these!
I’m glad it was of some use, i spent ages trying to find one to put in a Mag but thats as far as i got 
Keep us posted on how u get on with it.
I ordered two from Hobby King and today I got a shipped notice.
Well I got it some time ago, but now that I got back to making a headlamp I took some pictures with speaker chipped off. That’s a mm paper grid as a background.
One question thou, do you think I can cut the board at the red line or should I just cut it at the yellow line?
I see no harm in cutting at the RED line if you’re not planning on using the outputs