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LED Dash Light Upgrade

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Rob Glasgow said:
Bob, I think forward only lights will work fine for the turn indicators.
Click to expand...
I got inspired, looked around a lot and finally found some 'bi-polar'--that's what the ad says--LED E10 lights for the dash indicator lights. They're definitely brighter, but there's a problem: the on/off interval is erratic (the flasher can sounds normal). I think this is because, if you'll recall, early on in the LED days it would take a half-second or so for the LEDs to light up. My house is now almost completely LED, and some fire instantly but some still take a fraction of a second to light up, unlike an incandescent which starts to 'burn' instantly. Because of this, I theorize, the lights fire and go off at differing intervals. It's kind of distracting and annoying but I'm gonna try to learn to live with this, if for no other reason than it's a real PIT back to replace them.
 
I have some LEDā€˜s in the bathroom that have that delay. Not all, just 2 of the 6 can lights in the ceiling. Drives me bonkers. My turn indicator light doesn't seem to have that problem. But then, I have only a sing light for both left and right.
 
My BJ-7s LED gage illumination solution and results. Red halo is reflection from rear parking lights also LED converted. No resistors required from this source.
 

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I was looking at an alternator conversion and saw "LED bulb should not be used for the red generator/alternator light on the dash". Does anyone know if this is true?
 
True. The incandescent bulb has a filament. The lightbulb has a resistance an LED does not.
 
The theory: The ignition light lights when current is being supplied by the battery (low RPM with a generator system, typically). That's why its intensity varies with engine speed. LEDs are, of course, 'digital,' which only indicate 'on' and 'off.' An LED will be 'on'--lit up--when a minimum voltage is applied, usually 5V. LEDs are polarity sensitive so, conceivably, if you put a pos. gnd. LED in a neg. gnd. car the light could be on when the generator is charging, but I haven't confirmed this; anyone tried it?

The practice: I put a pos. gnd. LED in my pos. gnd. BJ8; it functioned as expected (on or off, no varying levels of intensity, but some flicker at low speed). IOW, it worked, but I eventually put an incandescent bulb back in, 'just because.'

If you have an LED; give it a try and report back, at most you might fry the LED but, theoretically not. An LED is a diode, after all, which are used as rectifiers, which allow current to flow one way, but not another. Actually, diodes have high impedance in one direction of current flow, but are basically a short in the other (many/most have a constant voltage drop of 0.7V, and are sometimes used in series to step down voltage). There is a type called 'zener' or 'avalanche,' which will break down and conduct above a certain voltage; they're used in a simple overvoltage protection system called a 'crowbar,' because when they break down and conduct they usually cause a fuse to blow (like if you threw a crowbar across an electric train's third rail). Do a search on 'full wave rectifier' if you're curious. Diodes allow alternators to create (lumpy) DC current without commutators--aka 'brushless'--which is a wear item and speed-limited.
 
Bocaray said:
I was looking at an alternator conversion and saw "LED bulb should not be used for the red generator/alternator light on the dash". Does anyone know if this is true?
Click to expand...
Yes, it's true. The alternator may have a connection to the bulb that tells it to start generating power. Mine does. A friend had his bulb burn out and the alternator wouldn't work.

In stock car, the bulb has a voltage signal from the starter switch a voltage signal and from the control box. If both voltages are the same, no current flows and the light goes out, signalling that the generator is working. If the generator isn't working, it only gets a voltage signal from the starter switch and the light goes on.
 
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