It would help if there was actually some documentation on these repro's. Maybe the LED on it can handle 5 volts?
Agreed, but we can (somewhat) reverse engineer the specs with this simple test.
Best way to tell for sure is to use your multimeter in series to test how many miliAmps are flowing through the circuit below while the LED is forward biased/lit.
- Use one LED and one resistor as shown so there's no fancy serial/parallel circuit math
and it's also a best practice to use a separate resistor for each LED
and in this case it will keep you from exceeding the wattage and burning up a 1/4 W resistor like the ones you're getting.
- With a 2v LED and a 680 ohm resistor, you
should get something close to 15 mA.
- With a 2v LED and a 510 ohm resistor, you
should get something close to 20 mA.
12v ---- current limiting resistor ----
+ LED
- ---- red lead--multimeter--black lead ---- ground
If your readings are much lower (i.e. 2 or 3 mA), there's likely a current limiting resistor hidden inside the volcano button assembly. Post the results of both tests and I'll try to (somewhat) reverse engineer it.
I'm opting for a 1/4 resistor pack on Amazon with 60 levels of resistance. Would this be a good pack, and which ohm level would you use for that 12v?
That would be a fine assortment.
- The 680 ohm should be extremely safe. (15mA)
- The 560 ohm should be very safe.
- The 510 ohm should be safe. (20mA)
There is also a YouTube video of someone putting these into his A1UP by tapping into his 12v with a 220 ohm resistor without issue.
I'll take my 40+ years of experience working and playing to component level with electronics over the word of some YouTube rando that managed to get the LEDs to last long enough to shoot a video.
- I don't want to pick on him, but it's clear that if he
is knowledgable about electronics he isn't clearly conveying that info and isn't following best practices. Caveat emptor.
The measurements from the inline amperage test mentioned above will provide valuable insight into what you're actually dealing with.
Unless there is a current limiting resistor hidden inside the volcano button or the LED specs are
way outside the usual range for red LEDs, the video results do not make sense.
There's probably some unidentified variable in the equation because it's called Ohm's Law, not Ohm's Suggestion.
Scott