Garage door button light.

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Old 03-15-17, 01:26 PM
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Garage door button light.

Lighted garage door opener button - light quit working.

I've had this lighted button for years. Light quit working a couple months ago. Today I removed the button switch, and yup burned out bulb. BUT, the bulb wires are attached to the same contacts as the opener.
Why doesn't the bulb itself cause the opener to work? The bulb is closing the contacts.
I imagine it is the same setup for a common lighted doorbell button. Isn't the bulb itself closing the circuit for the bell relay?
Trivial, but makes no sense to me.
SteveS
 
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Old 03-15-17, 01:38 PM
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It does defy common logic.

To ring a door bell or activate a garage door opener..... when the button is pushed the resistance goes to 0 ohms. Basically a dead short and the device activates.

The resistance of those bulbs is very high. High enough that they don't cause a short.

The generic name for that bulb is a PBL2. If you search you'll find them widely available.

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Old 03-15-17, 08:01 PM
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Since this was asked, I was curious and thought I might replace my button with a lit one. Took it apart and it has a soldered in LED looking thing, doesn't look like these PBL2 or others in a search. Looks just like an LED I salvaged out of an old PC a few days ago. There is also a diode on the little circuit board (maybe a zener as a regulator?) can't tell much didn't get my jewelers eyes out. Could it be a LED? Would the wiring polarity affect it. LED's seem to last forever, surprised to find it in there actually.

Might have to diagram it out and get some thoughts.

Sorry for the hijack, but we both learned about PBL2 bulbs at least. Seem to be very common in doorbell buttons also. 2 for $7 on Amazon.
 
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Old 03-15-17, 08:09 PM
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An LED would work as a light too. It can be connected to an AC voltage and operate.

There would be no polarity to the connection but the LED only needs a few volts to light up so that very well could be a zener diode.

A small diode and a resistor of 1.5k-5k would probably be all you need.
 

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Old 03-16-17, 11:26 AM
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OP here again.
I miss having that light. Altho disappointed in the price of those bulbs. Costs less for the entire switch.
I have LED's & diodes. Kinda dim tho. I also have a few neon bulbs w/resistor. Might try one of those. IF I can squeeze it in there.
 
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Old 03-16-17, 11:31 AM
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Neon requires a minimum voltage of 65vac to fire so that won't work.
 
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