Power Switches For RC Locos

[BG John]

I'm trying to find the best way to turn the power on and off on RC locos in 4mm and 7mm scales. Most easily available slide and toggle switches seem rather big, especially for 4mm, and difficult to hide. I've order some very small slide switches from China that may be OK, but it's not really what I want.

 

I've read about using latching reed switches, that can be operated by waving a magnet close to them. This seems ideal, as it means the switch can be totally hidden, and the loco doesn't need handling. But where can you buy them? I've been scouring the web, and they seem very elusive. I read on a forum somewhere that they're not available in the UK.

 

They must exist though, as someone from CLAG has used them, and there's even a photo to prove it. Scroll down to the bottom of this page.

 

Are there other options. I know some systems can turn themselves on and off, but my DIY one can't turn itself on, and would need extra hardware to turn itself off.

[Bill_J]

Hi BG John

 

Best price I can find easily is on Amazon. I wouldn't call them sub-miniature, and they aren't latching. I had some, many years ago, that came from the key switches off an old IBM mainframe keyboard. Maybe you can find some from a surplus source.

 

Good luck with you hunt, regards

 

 billj

[fallen]

Some of the DelTang receivers use microswitches but they are not latching. The receivers can be turned off by command from the transmitter, and the microswitch is used to turn them on again using a magnet.

 

I use small switches like these

 

http://cpc.farnell.com/eao/09-03290-01/slide-switch-spdt-vert/dp/SW03106

 

They work fine and can be hidden under the loco, usually behind the cab steps is a good place.

 

Frank

[BG John]

Some of the DelTang receivers use microswitches but they are not latching. The receivers can be turned off by command from the transmitter, and the microswitch is used to turn them on again using a magnet.

 

I use small switches like these

 

http://cpc.farnell.com/eao/09-03290-01/slide-switch-spdt-vert/dp/SW03106

 

They work fine and can be hidden under the loco, usually behind the cab steps is a good place.

 

Frank

Do you know how Deltang make that work? Could it be done with an Arduino?

 

Too late for the CPC switch. I ordered some stuff from them the other day! I only need one for now, until my Chinese order arrives .

[otherplanet]

For basic on off, I have been using these tiny switches.

or a similar version with the knob projecting out the face.

Bought from China, via a well known online auction site.

I have found them very useful, due to their lovely small size. But can't remember exactly which supplier I used.

Probably the same or similar to what you have ordered.

 

Personal experience with reed switches was how precisely you need to position them over the magnet to get them to work well,

particularly if you want to cope with lots of different combinations of loco on one piece of track (or vice versa), so some standardisation of where you put the reed relative to the cab or similar point of reference might be useful.

[BG John]

This is what I'm making at the moment. A Dapol van with batteries and all the electronics, so to get started I can attach two wires and a connector to each loco, and plug it in. The electronics will all fit, but I'm not sure about a switch, without having it sticking out of the van body. When I get round to converting locos, I want to try to standardise as much as possible. It's a bit frustrating that there seems to be evidence that these mythical latching reed switches actually exist, but no one seems to know anything about them!

 

 

[fallen]

I'd guess the DelTang power switching circuit uses something like this

http://docs-europe.electrocomponents.com/webdocs/1539/0900766b81539987.pdf

 

The reed switch would switch it on then it would be held on by the microprocessor until told to turn off.

 

Standby current is very low to conserve the battery.

 

This one is only for 5v supplies as it is intended for USB applications. It would be OK for 1S installations but there must be other ones with higher voltages.

 

Frank

[Robin2]

I gave up on switches long ago. When I converted my N-Gauge Farish large prairie to BPR/C there was no room for any switch that I could find. What I did was install two pieces of fine brass tube (think of a piece of tube with a gap in it) and make the circuit by sliding a piece of brass rod into the tubes.

 

For my current card model of an OO Gauge LMS 1F tank I just slide a piece of 5 thou brass shim into the tender to bridge the gap between one of the battery terminals and the terminal on the loco. The switch really does not take up any noticeable space.

 

The other great advantage of these DIY switches is that they don't need any force to operate them. Even the very small slide switches need enough force that they would bend any card bodywork they are attached to.

 

...R

[BG John]

Having failed to find any from UK suppliers the first time I looked on eBay, I tried again and found some tiny ones. I've got a couple to try. I'm beginning to wish I hadn't decided to start my RC adventure in 4mm scale. I hope everything is less fiddly in 7mm!

[davetheroad]

As I charge all my batteries out of the locos and only need them to last for one operating session I just don't bother with switches!

 

Actually my latest Lima diesel conversions have enough power to run for about 4 hours so they have large switches, easy when you have lots of space available. They use 4 x AAA NiMh batteries or I can use a pair of small Lipos for one session, in which case the switch is not needed.

 

I like Robins idea of homemade switches.