Large Scale Central

Mounting Reed Switches?

Electronics Power and Sound
#1
I am looking for some new ideas to mount reed switches on the bottom of trucks for the track triggered bell and whistle.
 
I am using 1/4" dia. cylindrical reed switches, such as those usually supplied by Phoenix Sound. I like to mount them parallel to the tracks at a height that just clears the rail tops by about 1/8" or less. In the past, I have fabricated a piece of wood with two slots in it to hold the switches ( I know, a photo would help, but not now ... ). The wood sets the appropriate height, and the slots keep the reed switches in alignment (one on the left and one on the right). Everything is held in place with glue (CA and silicone). It works, but needs occasional repair (glue fails).
 
Any slick ideas out there? 
#2

I drill a hole big enough to get at the truck mounting screw in a small square of styrene and just silicone the square over the truck centre.
I then use square or rectangular styrene tube to lower the reed switch tubes to the appropriate height and styrene the tubes in place.
The convention for triggering is Horn/Whistle on the right travelling forward and the bell on the left.

#3

Tony Walsham said:

… styrene the tubes in place…

Explain please?

I have done something very similar, and I like it if I can get reliable glue joints. I think the silicone is good for joining the odd shapes of the truck to the flat styrene.

#4

Styrene cement the tubes in place. OK, I left cement out.:wink:

I also use super glue effectively and you could use silicone as long as you leave the joints long enough to harden up properly

#5

Thanks Tony. Just wanted to clarify. Thanks for sharing !

Starting with your “Square”, instead of my previous attempts with a rectangular shape got me working on a new design. I would like to use tie wraps to secure the reed switches to the Styrene. So a couple of holes for the tie wraps is all that is needed. I can still use a tab of glue if I need to. And, I can also run a screw through the mounting bracket into the truck.

I’m just trying to improve on what I have done in the past, as this installation will be for a public display and needs to be very reliable and long lasting.

#6

Wow, talk about perfect timing. I was going to ask some similar questions about mounting reed switches, as I will be installing sound in a couple of engines very soon. These will be my first attempts at installing sound units, so any pictures and/or ideas that you guys want to share are very useful. I’m glad that there is a ‘standard’ for the horn side trigger and the bell side trigger- that was going to be one of my first questions. What other useful info you guys got?

-Kevin.

#7

I know I don’t have any pics of whistle and bell triggers, but I thought I had some pics of how I mounted a chuff sensor. For the life of me I cannot find them.

It is OK to have sound trigger reed switches mounted parallel to the track magnet.
if you are using a reed switch and magnet for chuff timing, it is better to have the end of the reed switch pointing at the magnet on the wheel or axle. Otherwise the chuff signal may last too long.

#8

I use the flat reeds which have 2 holes and are easy to attach in many applications.

Available from Digikey.

I need to find the part number and post it here.

#9

Dan Pierce said:

I use the flat reeds which have 2 holes and are easy to attach in many applications.

Available from Digikey

I need to find the part number and post it here.

After coming up with several fairly complicated designs for mounting brackets, I think you have the right idea Dan. I was aware of these, but had dismissed them long ago, due to price and size. However, I found a Cherry MP201802 mini-flange mount that looks promising. A simple mount using a bolt and piece of tubing sized to lower it to the desired height above the rail, and “Bob’s your uncle !” ( My new favorite Aussie saying ? )

#10

Hey Del, the rest of that “Aussie saying” is:

…“and Fannies your Aunt”.

I make my own reed switches from tiny glass reeds and two strands of ribbon cable siliconed inside 1/8" ID styrene rubing.

#11

Correction: I will be trying a Cherry MP201801 Mini Flange Mount Reed Switch, NOT a Cherry MP201802. The 802 is a normally closed switch, and we need the 801 normally open switch.

So Bob wouldn’t have been my uncle, and Fannie wouldn’t have been my aunt. It would have just been me cussing, if I had ordered the wrong one.

My goal is to have a very reliable mounting scheme for a public display I am working on, which will be by way … battery powered !

#12

Just a follow up … I purchased some of the flange mount reed switches and found that in my most common configuration of mounting them to the bottom of a truck, they just didn’t work for me. They are useful in some applications where they can be mounted vertically from the frame or something.

I ended up using Tony’s method; i.e. laminating rectangles of .080" Styrene plates to the proper thickness to achieve the desired mounting height above the rail. Drill a hole in the center to access the bolster screw, and another towards the edge to run a bolt through the reed switch assembly and into the tang of the truck (I wanted more than just glue). Then glue the cylindrical reed switches to the plates, and some more glue here and there for added strength.

In the process, I discovered how wonderful a step drill is for drilling large holes in thin pieces of Styrene or other plastics.