Hermaphroditus
Well-Known Member
It involves using a zener diode. Perhaps someone more electronically inclined than me can tell me if the idea is correct, but this should work. It works in simulations.
Also, that picture needs to be revised. There should be a resistor after the zener but before the transistor so you don't *Can'tSayThisOnTV* flax up.
Basically, you select the correct resistance values for your LEDs and voltage in, the transistor is acting as a NOT-Gate, and the LED on the NOT-gate will light up when the zener diode disallows a voltage to go through, otherwise the other LED will light.
Essentially a zener diode allows voltage to go through only when it is past the zener coefficient. So dependent on what voltage your batteries are and what constant the diode has, your LEDs will light up accordingly.
Again, this may need to be somewhat revised as all I'm going off of is a simulation in which parts cannot be blown, but it works virtually. It's also rather compact.
But yeah, this may very well have many flaws.
EDIT: Yeah, there is one flaw that I am seeing so far. Right around the threshold of the Zener you will be getting no LED indication because the voltage is only like 1.2V, so it's showing at this point that it's neither good nor bad because there's enough to bypass the Zener diode to trigger the transistor but not enough to light the LED to indicate it's good. There're two possible fixes I can see, one is to just cut out the second LED and have a dummy-light that tells you when you need to charge by having a red LED light up, the other is to make the circuit a bit more complicated by throwing an amplifier in there to boost the voltage. For cost and practicality reasons I'd say to just take away the green LED.
Also, that picture needs to be revised. There should be a resistor after the zener but before the transistor so you don't *Can'tSayThisOnTV* flax up.
Basically, you select the correct resistance values for your LEDs and voltage in, the transistor is acting as a NOT-Gate, and the LED on the NOT-gate will light up when the zener diode disallows a voltage to go through, otherwise the other LED will light.
Essentially a zener diode allows voltage to go through only when it is past the zener coefficient. So dependent on what voltage your batteries are and what constant the diode has, your LEDs will light up accordingly.
Again, this may need to be somewhat revised as all I'm going off of is a simulation in which parts cannot be blown, but it works virtually. It's also rather compact.
But yeah, this may very well have many flaws.
EDIT: Yeah, there is one flaw that I am seeing so far. Right around the threshold of the Zener you will be getting no LED indication because the voltage is only like 1.2V, so it's showing at this point that it's neither good nor bad because there's enough to bypass the Zener diode to trigger the transistor but not enough to light the LED to indicate it's good. There're two possible fixes I can see, one is to just cut out the second LED and have a dummy-light that tells you when you need to charge by having a red LED light up, the other is to make the circuit a bit more complicated by throwing an amplifier in there to boost the voltage. For cost and practicality reasons I'd say to just take away the green LED.
