Direct Fit LED Bulbs

@Victor Bertolina posted:

This is the "inside" of a T &C bulb. (LED432R) This one did not last too long in the 022 controller. I am using 18v ac. If I decoded the resister correctly, it is 1100 ohms.

Victor,

There's clearly no reverse blocking diode visible in this design.  It's a major omission that permits this LED to survive for its rated lifetime only in DC applications.

It's no wonder that AC killed it.

Mike

I'm guessing the second band is black and it's a 1K resistor.  However, no diode, so it wouldn't have a long life.

Tremendous strides have been made with hobbyist LED's. For example, Evans Designs produces them with built in resisters which means you cannot install them incorrectly. You can also get bayonet and screw-type LED's that directly replace the equivalent incandescent bulbs. They are voltage forgiving in that they will operate in a voltage range from 12-18 (my estimate, not exact spec) with no bad effects. For instance I have replaced all my 0-22 switch bulbs and all my block signals with LED's. They generate zero heat and are brighter than the incandescent bulbs. You can also get them in all the colors of the rainbow. Readily available via Amazon and/or On-Line.

Dennis, I think you're missing the point that many of these bulbs are not designed correctly and lack the basic protection for the LED.

I do not follow. What basic protection?

Purest electrical thought:

LEDs will work in either low amp AC or DC applications.

However, for them to light for a long while you need to add a resistor and a diode.

Even though the LED is its own a diode another one should be in the circuit.

That thought is what I learned on this forum.

@Dennis Rosenthal posted:

I do not follow. What basic protection?

The diode Dennis, see many posts about the issue in this thread!

The typical LED has a reverse voltage specification of around 5V.  The peak reverse voltage seen by an LED without a protection diode with 18 VAC applied is over 25 volts!  Even with the series resistor, it doesn't take that long for the way over spec reverse voltage hits to kill the LED.

Gunrunnerjohn, I see your point. To the best of my knowledge the LED's from Evans Designs are built with that protection. I cannot say the same for those purchased on line from many of the Chinese companies. However there is an offset. LED's cause less damage to plastic because they are cold. They are brighter which can be a +/- depending on what you want to achieve. They come in rainbow colors, which is an advantage. And if they burn out, no biggie, just swap in a new one. Just my opinion guys. I have not experienced any burn out issues yet.

@Dennis Rosenthal posted:

... the LED's from Evans Designs are built with that protection.

AFAIK, Evans Designs does not have any/many "Direct Fit LED Bulbs" per this thread title.  By direct fit I'm interpreting that to mean bayonet, screw, wedge, etc.  In this OGR thread, a wedge-style LED was dissected showing the protection diode.  It is a 1-cent component about the same size as the 1K resistor shown above.  Here's a photo hijacked from that thread so there are some extraneous labeling:

The point is it should be possible for the manufacturer to fit the diode into the base of most if not all "direct fit" bulbs used in O-gauge switches, lockons, passenger cars, etc.  Obviously that 1K resistor was installed manually so the extra labor to solder on the diode to the other terminal of the LED should not break the bank.

@stan2004 posted:

The point is it should be possible for the manufacturer to fit the diode into the base of most if not all "direct fit" bulbs used in O-gauge switches, lockons, etc.  Obviously that 1K resistor was installed manually so the extra labor to solder on the diode to the other terminal of the LED should not break the bank.

Stan,

Agreed.  Leaving the diode out is about the most ridiculously fundamental design error one could make.  Unfortunately there are millions of LED applications done this way (without the diode), and we see them failing everywhere around us because of it.

As these millions fail they give LEDs a bad name (Aren't they supposed to last for 20 years, or more?), that they definitely don't deserve.

As a consumer choose what you buy carefully.

From the source's perspective an informed consumer is a better customer, and brings guaranteed return business.

Mike

If your looking for "flangeless" LED bulbs....I think I can help.

I'm in the process of building an Amazon order list when I came across these LEDs....

As you can see, there is no flange at the bottom of the LED itself. These are replacements for LED Christmas lights.

Amazon's ASIN number is B08KZRZ54C; I believe you can search on that directly. I found these my searching on "flat top concave wide angle christmas led".

Hope this helps!

I have used these products for years, with no issues. Note they run on AC or DC. But you have to pick the voltage range and the light color and the color temperature

Bayonet LEDs

John, my experience is identical. Have not had any issues with the bayonet or the screw type (E10 in most cases) bulbs available on line.