Flashing 3mm LED's

Martin Derouin posted:

 

...Any one have any ideas,  I brought them at Brighthouse in Washington state,  I tried several pairs and get the same results...

My idea is for you to post a link showing exactly what you have!

Tried searching "Brighthouse flashing 3mm LED" but can't seem to find what you have.

Are you simply connecting to AC track voltage?

Here is the link to what I got: 

https://www.amazon.com/gp/prod...00?ie=UTF8&psc=1 

I have the leds connected to a full wave bridge rectifier...for the DC> needed

MARTY

On the bench where they worked, you used the same AC transformer and the same bridge-rectifier?  Trying to find out what's different between the bench and track.

Some thoughts.

1. The link says 12V DC.  I did not see a range of operation like 9V-18V DC.

2. Flashing LEDs incorporate solid-state circuitry which amounts to a timing circuit.  Timing circuits like to be fed with a stable/constant DC supply.  If all you use is a bridge-rectifier (no capacitor) to supply the DC from AC track voltage, you effectively have pulsed DC which drops to 0 Volts 120 times per second.  This may confound the timing circuit. 

3. If I understand your comment, it's when the caboose is "running behind a train" that there is no flashing.  Does this mean it flashes when the train is stopped?  This ties in with above comment where dirty wheels/rollers/track might be supplying intermittent or choppy track voltage making the DC voltage (after the rectifier) that much less stable.

FWIW, I've never successfully run flashing LED's on just rectified power, I've always needed filtered DC for proper operation.

What would be used to filter the DC John...

Marty

Yup, like gunrunnerjohn said, the DC must be filtered for most flashing LEDs.  I use large (47uF) and small (~10nF) caps on the DC.

Once you have rectified the AC with either with a diode or a bridge, then I use an electrolytic cap for filtering.  For a single flashing LED, the 47uf would probably do it, for more than one, increase the size of the capacitor. 

Would a cap that is used on a TMCC engine motor work, have plenty of these...

Marty

Nope, those are typically 1uf 50V non-polarized caps.  Not enough capacitance.  I'd be looking for at least 47uf, and preferably more like 100uf.

I ordered some in the link above./..

Marty

Still waiting for parts I ordered so I ordered some flashing LED's from Evans Designs,  they came on Saturday and I installed them today, they work like a charm, Time to get it working, about 15 minutes.  Man do they ever "pop"...

Marty

@gunrunnerjohn,

I've searched the OGR posts (and google as well), and this discussion is the closest to my issue, very close actually.

I bought prewired LEDs from EDGELEC (I've used them a lot for just regular LEDs and resistors) that are supposed to be red blinking, 9v-12v.  I hook them up to a test connection on my 1033 transformer, and they light but do not blink.  I'll be using them in strictly AC mode.  Would you please enumerate what other things I need to add in order for them to blink?  Remembering that I'm not all that swooft at this stuff, a picture would help a lot!

Thanks in advance.

Flashing LED's have to be DC powered, they have a tiny flashing circuit on the chip that must be DC powered.  So, in order to get them to flash, you'll have to add a diode and a small electrolytic cap, probably around 47uf, 35V will do.  That's in addition to the current limiting resistor.

Perfect. Thank you. This is my second batch of flashing leds. I thought they shipped the wrong ones in the first batch. When the second batch was the same, I said ‘Hmmm, me thinks I don’t know what I’m doing’.

Thanks again.

Every day is a new experience.

@Martin Derouin posted:

Still waiting for parts I ordered so I ordered some flashing LED's from Evans Designs,  they came on Saturday and I installed them today, they work like a charm, Time to get it working, about 15 minutes.  Man do they ever "pop"...

Marty

From Evans Designs website:  "With a super compact full wave Bridge Rectifier for "always on" forward and reverse operation, a capacitor, and a dropping resistor . . ."  They work because they already have the rectifier and capacitor as GRJ mentioned.  They will run on 5-19V AC or DC.

Your first purchase of prewired 12V flashing LEDs only have a dropping resistor.  They will only operate on filtered DC.

Here is the circuit GRJ was suggesting:

Make sure the polarity of the capacitor matches the rectifier outputs.

Bob

I got my flashing red LEDs to flash, thanks to @gunrunnerjohn and @RRDOC.  I actually bought the components for both methods.  The blinking 3mm edgelec leds were bought from the big online store for $0.32 each, and came prewired.  I bought GRJ's diodes and caps from the same place, cost was $1.50 per unit for both (free shipping).  I bought the rectifiers for LEDs from Evans design.  I only bought 4, and the cost for each including postage was about $3.  The one on the right is with the rectifier, and the one on the left is with the capacitor and diode.  Even though the rectifier is twice the price, I will probably use that since it has a smaller footprint.

Thanks to all for your help.

So, the attached video shows what I was after.  I got a nice 41 switcher, but Lionel didn't put in any lights.  I put in a warm white LED for the headlight a month ago, but I wanted a flashing red LED for the light in the rear.  It may not be prototypical, but that's what I wanted.  After figuring out how to get the LEDs to flash, the installation was a cinch.

My next flashing red LED will be to add one to a 60 trolley I just got.  I've posted about lights on the 60 trolley on this thread.   The ones I've already done are static, but I'm not going to change them since it's actually not that easy to put directional lights in them.

@texgeekboy posted:

The ones I've already done are static, but I'm not going to change them since it's actually not that easy to put directional lights in them.

It would be fairly easy to add directional flashing lights.  As long as the trolley is moving, you can tap the polarity of the drive motor to power the flashing light.

Thanks @gunrunnerjohn, but I didn't properly phrase my post.  I do have directional ability with the headlight/taillight on both ends in the first one I did.  What I meant was there are 6 wires (2 ground, 2 white, 2 red), and it's a little snug in there even with kynar (sp?) wire.  While it's serviceable, I don't want to open it up to do that.  The red lights on each side of that one will remain static so I can keep my sanity.  I'll be putting directional lights (white/flashing red) in my next #60.

I really want to thank you for all your suggestions.

OK, that makes sense.