DCC Decoder and Momentary Contact for about 5 amps

Model Railroader Electronics and DCC
1

I am thinking a project through.

First, I need a small enough solenoid to fit in an HO caboose or passenger car for animation of something in the car. (I will not say what the actual animation is for right now.) All the solenoid needs to do is snap a plunger back and forth. I find the Peco one for turnouts plausible for a reasonable price and it will fit in the cars. (I plan on adding a spring so the rod will stay in position just like the turnouts. And, like most Peco products, it appears to be bullet proof.) So far so good, I think.

My preliminary research discovered some high tech industrial solenoids small enough, but the price is either too high or the supplier will only sell them in quantities for commercial applications. Yes, there are other model railroad solenoids available used to actuate turnouts, but they are too large to fit inside HO rolling stock from what I can tell. For the most part, I am dealing on average with only about 1 inch in height and width inside the car but more length. With some gimmicks and cutting a filing, I can either stand the Peco solenoid straight up or at an angle to make it fit and work. And with a caboose I could cheat and use the cupola for more space. (I did some perelimary research on the Flea too and it is only sold with the turnouts and I don’t want to deal with tearing one down, the price etc.)

The Peco one, however, needs lots of amps to activate it. However, that shouldn’t be a problem with the 5 amps and 16 volts AC available through the tracks in a DCC set-up. (A good booster is a plus here I gather.) The solenoid does, however, need momentary contact to activate it or it will burn up. This does, however, have its advantage in that it will only hog power for a second.

I plan on adding wipers under the cars to provide power from the rails via the axles. Sound plausable so far?

A decoder is, of course, needed to operate the solenoid from my hand held cab. However, my knowledge and experience with DC

2

Check out RC model airplane servos.

3

Don’t know the size of this:

http://digitrax.com/prd_statdec_ds52.php

But a stationary decoder designed to throw a Peco switch seems like it might be just the thing!

4

Ken,

Try:

http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDrillDownView?langId=-1&storeId=10001&catalogId=10001&freeText=solenoid&search_type=jamecoall

As to decoders, I haven’t seen any with anything greater than .5 amps on the function outputs. However you could use a O/S decoder with a 2 amp motor output and hook it up to the decoder outputs…OR…

Hook a standard stationary decoder function output to a 5A mechanical relay which is connected to a a capcitors which is then connected to resistor and a full bridge rectifier which is connected to your wipers. But then at 5 Amps you’ll likely blow your booster with a short.

Mechanical relays are better suited to handling this kind of current.

If you need a schematic, let me know Ken.

5

It might help to let us know what you are trying to do. There “might” be a better solution that requires less current.

Rich

6

Thanks all for the replies so far. I have sent emails to two suppliers of stationary decoders (one with a servo motor) to see what the dimensions are.

I am also looking at the small, low current solenoids Jameco link. If I can use one of those, I won’t have to worry about the 5 amp thingy with the Peco one. Just to show you how many amps a Peco solenoid needs, I will tell you that I hooked one up to an off brand model train transformer with an AC terminal and that was not enough to throw the solenoid. (It is lised as 5VA.)

I have to admit that I like the Peco one because it is so simple and makes a buzz and clunk sound when it activates. This would be handy for my application as I can hear it activate even though my caboose might be out of site… Sorry, still can’t tell you what the solenoid will be activating.

7

Let me guess, it’s gonna be a crew member that pops out of the caboose?

Or it’s gonna be a Jaws scene, where a shark pops out of the water? (like at Universal stuidios) LOL now that would be cool.[:O]

8

I was thinking crewman in the caboose cupola who rotates 180 degrees and looks the other direction. I remember an article before the days of the Internet and DCC where someone had made a HO diesel loco with the engineer who would turn am look in the opposite direction when the loco direction was changed.

Rich

9

No, this a legitimate function that will be used in train operation. The idea with the crewman that changes the direction of his head depending on the direction of the train was done in O scale, and I think John Armstrong did it. I believe that article may have been republished in one of the Kalmbach electronics books.

I am holding off being more specific because if I can get it to work, I would like to see if I can get the idea published in Model Railroader. Of course, I would provide credit to anyone that can help me out. Once you get photos and a “how to” published on the net, it can be the kiss of death for publishing hard copy.

10

I would be very leary of any coil device that sucks up as much current as a DCC system can put out. I would suspect a slow down at the least when this thin is activated. And the massive BEMF to teh rails may mess up the DCC signals to the trains.

Tam Valley Depot has some nice DCC servos that I would feel would be much better for your application.

http://www.tamvalleydepot.com/home.html

Jim

11

The mini-servos and controlling DCC decoder offered by Tam Valley Depot may be just what you need. Check out their web site at http://www.tamvalleydepot.com

12

[quote user=“jrbernier”]

Tam Valley Depot has some nice DCC servos that I would feel would be much better for your application.

Jim:

I already have an email out the Duncan at Tam Valley for dimentions. It would be nice if it would fit as it would have about everything I need.

13

Tam Valley Depot’s Singlet Decoder measures 1.25 inches square and .75 inches high. Their Micro Servo 9 G measures1.25 x 1.25 x .5 inches. Interconnecting wires and the servo’s actuating horn and linkage add to these dimensions.

14

Thanks for getting me the info quicker that Duncan at Tam Valley. It looks like that will not fit in the Wabash caboose resin kit I am building right now but I just purchased a DT&I wide vision RTR car on ebay. Maybe that will have more room to experiment with.