I have two staging yards on my layout with yard ladders plus each has an additional turnout to create a return loop. I am using my own control circuits with diode matrixes and R/S flip flops controlling a relay which reverses polarity for each turnout. The return loop turnout is controlled separately with a similar circuit. These all have Tortoise motors. This has been working fine for several years but recently I have been having some issues with one of the yards. When the turnout for the return loop moved, it sometimes causes some of the turnouts in the ladder to move. This is random and does not happen all the time. I believe I have narrowed it down to the Tortoise motor generating noise as it runs and this noise being picked up on the inputs to my logic. Has anyone else had electrical noise problems with Tortoise motors? If so, what was the most effective method used to suppress it? Capacitors, ferrite rings, etc.
On my friend's layout, we found that there is a pretty large voltage spike when a stalled tortoise has its input reversed. This was causing issues for an Arduino that was mounted nearby. I put high voltage caps across each one in order get rid of this. In the image from my portable scope, you can see the ringing that occurs, which is over 300 volts.
Yikes, those are some big spikes. I don't have anything approaching that level but apparently it is enough to couple over to some of the input wires on the companion circuit. After trying several ideas, I mounted a .01uf ceramic cap from each motor contact to the motor casing. They had to be positioned so that they would not interfere with the movement of the arm. Tested heck out of it this evening and seems to be fine now. My Tortoises are from 8 to 30 years old and I suspect of the commutators are starting to spark and arc more. Until this year, I was using a Digitrax DS64 for control on one of the yards then the inputs died. Now I wonder if this could have been the cause. Thanks for your input, nice image from your scope.
Follow up: I have corrected the problems I was having and put up a post on my layout blog with the details. http://palisadecanyonrr.blogspot.com/2023/12/tortoise-motor-noise-problem.html
Great detective work and also the fix , way above what I'm capable of. I'd considered getting a scope in the past and even recently with all the options there are now but at my age and all the other things I'm working on I can't imagine finding the time to learn how to use it and not sure what I'd use it on but they sure are cool. Thanks for the post and the link. Sumner
Guys! I have 2 Hantek's and don't know how I would get by without them. I am always looking at signals; pulse width or rise/fall times. Volt meter is just not good enough for that. I tried one of their 8 port logic things ( made for automotive ) but found that it was not fast enough for debugging ASM projects. Does ok for slow signals on a MRR for the most part though. Welp, google LHT00SU1 and you will come up with a 8 channel thingie for under 40 bucks. PulseView is available for this open source. Ebay link: https://www.ebay.com/itm/183693418624 for the one I got, Amazon has ( had? ) these also. Later
I used oscilloscopes all through my working career. These were all either Techtronics or Phillips and took up half the work bench. I've been wanting to get one for home use and these new ones are small enough that this fits on a small shelf above the work bench. The screen is the same size and it has all the same features as what I was used to. I've been really happy with the Hantek so far.
