Tach sensor

A tach sensor provides it's own light, one of those two little windows is the emitter, the other is the reflected light pickup.  No outside light needed.

Outside light messes them up!  lol

Actually most reflective sensors like the one shown use infrared light. They are fairly insensitive to indoor visible light. What you use to reflect the light will have the most effect. Also the sensor should come with some data that gives the optimum distance from object.

Pete

Pete,

If you run your train past a window on a sunny day with the shell off, it will act pretty crazy.  The first time I tested an engine like this in the shop, I didn't know what was going on.  I had to laugh a bit when it settled in.

Dave

I'm guessing for that sensor, around 1mm will turn out to be the correct spacing.  The MTH one, as well as the one I use for my Chuff-Generator both work at 1mm.  Dave is right, sunlight will drive them crazy.

David Minarik posted:

Pete,

If you run your train past a window on a sunny day with the shell off, it will act pretty crazy.  The first time I tested an engine like this in the shop, I didn't know what was going on.  I had to laugh a bit when it settled in.

Dave

 

Dave, Sunlight does have infrared. Indoor light, not so much unless you are using heat lamps. The better photo diodes/transistors respond to a fairly narrow bandwidth in the spectrum.

Pete

Thanks Pete!

Well, I guess it wouldn't hurt to fire it up and find out. 1mm is about .040, so I might have to move closer by about .040, if it doesn't work. Thanks for everyone's input, I will let you know. Bob.

I fired it up and everything works like it should. Boy the NWSL truck sure operates well at a ratio of 25:1, slow  start speed.  I did have one problem, one of the headlights went out, guess it went bad, checked the wires and they are correct. Where is the best place to buy the proper led? Bob. 

I forgot to thank everyone for your help, I appreciate it. Bob.

machiningfool posted:

 Where is the best place to buy the proper led?

It would be useful to know something about the LED that's in there now.

This white led came out of an O gauge MTH PS3 SD-70 diesel.  Is that a 20 ma. led? There are two of these led's on the same circuit, same plug and the one went out. Bob.

They should be standard 3mm white LED's.  I'd replace the pair as different makers have slightly different colors and operating voltages.  I buy LED's in bulk on eBay for a couple cents each.

Thank you I will order some. Bob.

I believe it is in the upgrade kit manual that gap should be 0.8-1.2mm, or close to that range.  1mm is what I always shot for.

My Chuff-Generator requires 1mm, and your range works fine for it.  I believe many of the reflective sensors like that are similar in specifications.  The sensor actually indicates it peaks earlier, but I have the best results sticking very close to 1mm, and that's never failed me.

I am learning a lot from the O gauge forum.  I have never seen a graph like that. It's great. Never can have too much info.  After asking the previous question about letting light into the housing I remembered how infra red works, correct me if I am wrong, it supplies it's own light source, doesn't it. So it can be in complete darkness.  By that graph, the collector current in my setup is .4.  At that distance, the control was smooth from idle to max speed, in my case to scale 70 mph. Soon we shall see how it does under load.  In my E-8, I didn't have room for batteries, so I put them in the B unit and the TIU in a baggage car, but in this P42 there is enough room for my three batteries. I will put the TIU in a passenger car, box car,  or baggage, haven't decided yet.  I wish they would make the TIU smaller. Thanks for all of your help guys, I appreciate it.  Tomorrow I will mount the trucks and arrange the wires, boy lots of wires. Bob.

I probably should have told you guys that I mainly post on the G scale forum under rbrown7713 and posted about this Genesis loco I am making, kitbashed it from an LGB Genesis, scaled it down to 1:32 and a bunch of other stuff. Here is a better picture of the Genesis. Bob

Hack!

Just teasing. This forum is a great place to get help and learn more about trains. Just when you think you know something, new stuff comes out and the learning starts again. I remember learning from some very smart people in my past, that you can always learn something new. I believe, it keeps us young.

BTW I think keeping the grease and grime off of the tach reader and flywheel, can be tougher in some G scale conversions.

Number one, running outside is much tougher. Summer heat has beat me a few times now.

You are better off erring on the side of larger gap.  While the .8 may be peak, you fall off the cliff at a lower gap as we found out with John's super chuffer. G

Yep, George just found out that having it just slightly too close is bad.   I again recommend 1mm as that's where I test my Chuff-Generator, and all the installations with that spacing have worked really well.  On that graph, as George says, the close spacing has a steep slope, much more gentle on the wider spacing side.