Thanks and more questions
I want to thank everyone who has given me feedback on this circuit. And now of course I have a few more questions.
That could be easily solved with a small series resistance I would imagine.
A note on the site where I found the schematic stated
Important: to simplify the circuit and improve
the performance, no protection was added to d4.
You must set r2 & r3 to ground before starting!
If they are adjusted to the d4 side, parts will smoke!
How would I ensure that the above release of the magic smoke could not happen?
My answer would be that if it worked in 1991 it should work just fine now
In all seriousness, where is the fun in doing it with an IC? ICs are fine for large, complex devices with multiple functions and I/Os, where saving space and cost is an important consideration...but for a little DIY project like this, discrete components are a lot more fun to put together.
Well, I am researching this as a possible circuit to offer to motorcycle owners. Big twin cylinder motorcycles have a hard time starting due to many reasons but one of them is that the riders park the bikes with the batteries half depleted. Then when they try and restart it overtaxes the batteries leading to premature battery failure. Many riders eat a battery a year which contributes tremendously to the safe disposal problem of lead acid batteries.
So the goal here is to produce a simple to understand easy to mount indicator that will help the riders extend the life of the batteries.
And that means cost effectiveness is important along with small size.
I think the circuit is not the best way to go.
The setpoints for yellow and green depend on each other too much and therefor the circuit is difficult to adjust.
You'd better off using a window comparator.
Boncuk
Is there a circuit online anywhere that will accomplish the same function as this circuit that uses a more accurate or easier to adjust/maintain topology? One that uses the mentioned window comparator or something equally as accurate?
One of the main appeals to me of this circuit is that is shows multiple states using only 3 LEDs.
Again, thanks for all the feedback and advice.
M./