Electricity is Witchcraft

"ADabOfOppo; Gone Plaid (Instructables Can Be Confusable)" (adabofoppo) 04/04/2019 at 11:28 • Filed to: Bulbs, GTI, Magnets

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I legit think it’s magic.

So the center rear brake light bulb on my GTI burned out. I have a Pulse brake light resistor installed that pulses the center rear light 4x when I touch the brake pedal to stop.

I need to replace the bulb and would like to get an LED so it doesn’t burn out so quickly, and if possible find one that is slightly brighter than stock so it catches attention even more.

But looking at LEDs and bulbs online makes zero sense to me since I do not understand electrons.

3point8isgreat > ADabOfOppo; Gone Plaid (Instructables Can Be Confusable) 04/04/2019 at 11:37

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You’re not wrong. - A Mechanical Engineer who also thinks it’s magic.

WilliamsSW > ADabOfOppo; Gone Plaid (Instructables Can Be Confusable) 04/04/2019 at 11:39

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Starred for the ICP reference in the tags.

Not to pile on to the magicks problem but is it possible that the pulse resistor is bad and not the bulb? I would expect the bulb to last a long time - I’ve had 2 of my cars for a combined 32 years and 280k miles and have replaced exactly 1 taillight bulb in that time.

RamblinRover Luxury-Yacht > ADabOfOppo; Gone Plaid (Instructables Can Be Confusable) 04/04/2019 at 11:39

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The center light pulsing “resistor” is probably solid-state with a chip. That being said, it *shouldn’t* care too much about wattage, unlike a thermal flasher, so you should be okay searching for a watt range brightness equivalent to the old bulb in LED or brighter - lumens to lumens, not watts to watts.

Look up your old bulb, look for a lumen rating if you can, get something brighter with the same base size that will fit the housing.

The LED will in likelihood use less power, so it shouldn’t put the flasher at risk.

Highlander-Datsuns are Forever > ADabOfOppo; Gone Plaid (Instructables Can Be Confusable) 04/04/2019 at 11:57

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I’m a civil engineer and I still get electrocuted on a yearly basis because I don’t understand electricity.

Snuze: Needs another Swede > Highlander-Datsuns are Forever 04/04/2019 at 12:08

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Are you a ghost?

jimz > WilliamsSW 04/04/2019 at 12:14

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1) this is for a CHMSL which uses much smaller, shittier bulbs

2) thermal cycling will accelerate fatiguing of the filament

3) these “pulsers” are usually just interrupters, which can’t give any more power to the bulb than it would get just by being on normally. 

LOREM IPSUM > WilliamsSW 04/04/2019 at 12:17

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Could be, or it could have helped to hasten the bulbs demise. Magic is hard to understand sometimes. I’ve had to replace more rear bulbs in my e38 than literally every other vehicle I’ve ever owned all put together. Even with completely different housings, it would just constantly eat rear bulbs. Part of me thinks it just kills them so it has something to gong about, but I actually think the system that monitors bulb health is somehow responsible... only because I have no other possible explanation. It’s not the same bulb or even housing either, but almost always in the rear. Hexerei.

jimz > ADabOfOppo; Gone Plaid (Instructables Can Be Confusable) 04/04/2019 at 12:21

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it’s not too hard. find out what kind of bulb type your CHMSL takes (912 and 922 are common,) and find an LED replacement which fits the socket. Then you want something from a reputable name like Philips or Sylvania which is designed to emit light as omni-directionally as possible so it works with the reflector inside the housing. Those cheap no-name LED bulbs don’t really do this, so you end up with a “spot” of light in the middle of the lens.

finally, if it’s a non-keyed socket like for 912 or 922 bulbs, you’ll probably have to plug it in with the correct polarity. backwards won’t hurt it, but if it doesn’t light up, pull it out and plug it in the other way. 

lone_liberal > jimz 04/04/2019 at 12:37

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LOREM IPSUM > jimz 04/04/2019 at 12:56

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Als o of note, the cheap ebay/aliexpress units often fail prematurity.

I ordered 3 different pair of led fogs in varying color an d design for my FX . One pair had one that arrived  doa. One pair looked and worked great, until one stopped working a few months later. The third work, but aren’t even close to the kelvin rating they claimed to be and their output is weak so I may not even bother installing them.

Also had a pair of ebay led drl’s. They were bright af, matched the headlights perfectly, but again one went out after a couple of months. Replaced those with some much less bright single (or was it dual) diode Sylvania bulbs which haven’t given me any grief aside from the purchase price.

jimz > Snuze: Needs another Swede 04/04/2019 at 13:11

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i c wut u did thar

jimz > 3point8isgreat 04/04/2019 at 13:13

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I did OK with basic circuits DC and AC. where I lose the plot is with stuff like digital logic and ICs.

as far as I’m concerned, ICs are magic devices which take in electricity and put out Fortnite. 

MasterMario - Keeper of the V8s > 3point8isgreat 04/04/2019 at 13:49

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Mechanical Engineer checking in...the basics are pretty straight for ward. But start talking about impedance, reactive, and apparent power and I go cross eyed.

MasterMario - Keeper of the V8s > Highlander-Datsuns are Forever 04/04/2019 at 13:50

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I always go with the “don’t touch” philosophy when dealing with electricity, unless I’ve personally checked or watched someone check the voltage with a meter.

Highlander-Datsuns are Forever > MasterMario - Keeper of the V8s 04/04/2019 at 14:00

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I replaced a broken light switch without shutting off the power, that’s the last time I do that. I do have a tester and use it for all things now.

MasterMario - Keeper of the V8s > Highlander-Datsuns are Forever 04/04/2019 at 14:17

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I still have a tendency to start doing stupid things but usually catch myself. I started replacing a broken switch too with shutting off power, got the switch out of the receptacle before catching myself and being, “this is stupid, it takes 30 seconds to go turn off  the breaker”

Future Heap Owner > jimz 04/04/2019 at 14:20

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Don’t you have to wire in a resistor if coming from a traditional bulb, or the LED replacements all include that these days?

Future Heap Owner > jimz 04/04/2019 at 14:22

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Small   digital logic circuits are  the kind of circuit I’m comfortable with because I can ignore so much of the physics beyond V=IR to match voltage.

jimz > Future Heap Owner 04/04/2019 at 14:59

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well, there’s two things here. if you’re talking about the current limiting (ballast) resistor to protect the LEDs, those are (or should be) built into the bulb assembly. if they’re not then it’s a piece of junk. you should only need to worry about ballast resistors if you’re assembling your own stuff from component LEDs.

if you’re talking about those resistor kits they offer with LED tail light bulbs, that’s just to lower the apparent resistance seen by the BCM to prevent them from “rapid flash.” only important if you’re using them for turn signal bulbs; the apparent resistance of the LED assembly is so high the BCM sees it as an open circuit (burned out bulb.)

jimz > Highlander-Datsuns are Forever 04/04/2019 at 15:02

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n.b. “electrocution” implies death. You get shocked  once a year.