The Lowly LED, A Primer

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The lowly LED (light emitting diode)adds an indicator to your DIY mod that shows that it is functioning properly. In it's simplest configuration, the LED goes directly across the atomizer connector.


Make sure you use a resistor on one leg of the LED (contrary to popular belief, the resistor can go on EITHER leg). LEDs will shine brightly for a bit then burn out if a resistor is not used in series with the LED. The resistor's function is to control the amount of current flowing thru the LED. For general use, a 420 ohm resistor should suffice though some people prefer slightly lower resistance (like maybe 220 ohms), which will give you brighter light output but will also reduce the life of the LED.


Your LED will normally have 2 leads coming from it. The longer lead indicates the positive side, the shorter is negative. Does it hurt to put the LED in backward in a circuit? Normally No, but it won't work, as an LED is a diode, meaning it will only allow current to flow one direction.


Bi-color LEDs will normally have 3 leads, the center being B+, the longer of the outer leads one color (the dominant color) and the shorter will be the other (non-dominant). Both outside leads will be B- (negative). With a bi-color LED, only one resistor is required, as only one of the 2 diodes inside the LED will be on at any time. If both outer leads are activated, the dominant takes precedence. My LEDs, for example, are red/green 3mm LEDs. I use Green to indicate my master switch is on, the red when the atty gets power (when you vape). I use this configuration to remind you that the master switch of the PV is turned on (green) and that you should start inhaling when red.


LEDs are probably the least expensive addition you can make to a homebrew mod, and one of the most important. I use that Ebay place for all my LEDs and most other electronic parts, I get it all from the Orient. Takes a while, but who's in a big hurry anyway?


In fact, except for the atomizer connector, everything you need to build a boxmod (including the box) can be bought way cheaper on Ebay from places like Vietnam, China and Hongkong. If it weren't for the 510 or 801 connector, my mods would be completely made from Ebay parts (including batteries and charger).


So ends the lesson for today.


More questions about LEDs? Post your questions in this thread.

 

Alan,
Does an led's brightness vary only by the resistor used or also by voltage? Let's say my mod was variable voltage, should the led be brighter when used at 7.4volts vs 3.7 or would it be the same? On my Precious, the led brightness remains the same no matter what voltage I set it at but I have noticed that the unit with the led does not hit nearly as hard as the unit without the led even when using the same battery. This leads me to believe that the led consumes considerably more power than I thought.

Aloha, Keith

 

By resistors Keith, I have noticed on mods of mine that i made that didnt have resistors the LED's would be really bright. After the resistor added to it they are what ever. But ya i built a single battery mod just for the LED that took a 10440 battery and it works really well with a 5mm LED.

 

Keith that would entirely depend on how they wired the LED into the circuit.

LEDs do consume power, IMO on a 14500 mod the led if installed like Alan does his can take as much as 20% off the life of the battery if you forget to switch it off. Constant trickle draw can shorten your vape time from 5 hours to 4 just by leaving the main switch on.

As far as it taking away from the power going to the coil once again that would entirely depend on the LED and the installation method.

If it is a color changing LED then it would require a little voltage and current downstream of the switch and essentially take some away from the atty. Should this be noticeable? NO but, it can be depending on a lot of different factors.

I myself do not care for the added "bling" of an LED on my mads. I just want to push the button and vape.

 

The way I understand it, yes, the brightness will depend on both the current and voltage, cause current rises with voltage rise, assuming a fixed resistance. My suggestion would be to use a resistor that would limit current to the LED's spec at your highest voltage. Then, as voltage drops, the LED would become dimmer. That would be a good indicator of voltage, once you get used to the unit.

The resistor on the LED is way higher than is the atty resistance, almost 100% of the current should go thru the atty itself. I can't imagine that the LED, if wired correctly, should make any noticable difference in vapor production, but I could be wrong ???

Regarding your Precious, perhaps the LED is wired to show battery, rather than VV output, voltage. In that case, the LED should always be the same brightness.

Hope that helps a bit ??????

 

but it's so pretty LOL

 

Thanks for the replies guys!!!

Alan, would you be up to try and repair a broken Precious that I have? I would pay you of course but would want it back. Since I cannot tell you how it is wired because the damn thing is sealed with some kind of epoxy or resin, you would have to find something to dissolve the epoxy without damaging the rest of the internals. Let me know if you would like to try and I will send it to you.

Ps, the LED is not damaged in this one but I do have another one that I wanted to change, I think it is the variable voltage component that is the culprit. If you could, I wanted to delete the variable voltage component and just make it like the original non variable one.

Aloha, Keith