Wiring up reed switches

Lovely images Korm,

I love the robust simplicity of the early LGB type. Your home made ones look great too.

As I frequently say, I am really no fan of the modern LGB 17100. In my view the PIKO ones are streets ahead, but slightly fiddly to connect in comparison.

They do exactly the same job and are slightly cheaper too. Bonus!

Search for PIKO 35272

James
 
Last edited:
Thank you all for your replies.

So, in summary, connect one end of the reed switch to the power outlet in the module and the other end of the reed switch to the appropriate connection (deceleration or stop) in the module.

No need for any diodes as the switch turns on to give a pulse of power as the magnet goes over it and off to cut the pulse as the magnet clears it.
 
playmofire said:
Thank you all for your replies.

So, in summary, connect one end of the reed switch to the power outlet in the module and the other end of the reed switch to the appropriate connection (deceleration or stop) in the module.

No need for any diodes as the switch turns on to give a pulse of power as the magnet goes over it and off to cut the pulse as the magnet clears it.
Click to expand...

Gordon,

Yes!
 
Most reed switches are not rated for high current, and the contacts can burn easily. Be careful not to exceed ratings (meaning get the ratings), they are not general purpose switches. Often having a reed switch control a relay for high current applications.

Also, the contacts can be burned by switching inductive loads, so a protection diode is often required.

Greg
 
Greg Elmassian said:
Most reed switches are not rated for high current, and the contacts can burn easily. Be careful not to exceed ratings (meaning get the ratings), they are not general purpose switches. Often having a reed switch control a relay for high current applications.

Also, the contacts can be burned by switching inductive loads, so a protection diode is often required.

Greg
Click to expand...

I'm using Gaugemaster's reed switches designed for use with G scale and the locos operate off a maximum of 14 volts and will be pulling no more than four items of stock and usually only three, so all should be well.
 
James Day said:
I guess it is all down to the current:
I recall talking to the guys at AMR Electronics when I first stated using their reeds to operate the Tri-ang Relays to control my Minic Motorways.

They told me I was overloading the reeds and they would quickly burn out.

They didn't, (ok they did once or twice), but I guess most applications don't carry the full switching power through the reed, as I did, or as they do with LGB, so they last longer.

On modules like Gordon's, my guess is they the voltage and current going through the reed is low, so it won't matter if it is DC or AC.

James
Click to expand...

Thanks for your answers James and Dave. I think I'll stick to pressing the odd button or two! I had thought of reed operated sounds but I can see there might have to be relays and timers involved!
 
Greg Elmassian said:
It's not voltage, it is current. It might be nice to get the ratings as I suggested. I have seen a lot of reed switch failures. There are "heavy duty" reed switches too, Train Line puts them to switch frog current in their switches/turnouts/points.

Greg
Click to expand...

I use pull only about .5amps to .75amps, and the reed switch is not operating points or signals. It is simply telling a piece of electronic equipment that the train has reached a certain point in the track and should now be either slowed down or stopped, according to the point in the track it has reached.
 
playmofire said:
I use pull only about .5amps to .75amps, and the reed switch is not operating points or signals. It is simply telling a piece of electronic equipment that the train has reached a certain point in the track and should now be either slowed down or stopped, according to the point in the track it has reached.
Click to expand...

Your application is switching a 'control' signal to a piece of electronic equipment.. The current through your switch will be tiny..

What Greg is alluding to, is using a reed switch to switch the actual 'volts' to do something. - Be it a point-motor, or other device..
If you look at the picture of the LGB reed that Korm posted, you will see the inside of the glass envelope has blackened. My guess, would be this has been switching a inductive load (a coil on a point-motor perhaps?). When this is switched 'off' you get a large pulse, similar to how a spark is generated in an old-style car ignition system. Hence Greg suggesting a 'quenching diode' to safely conduct this spike away.
 
PhilP said:
Your application is switching a 'control' signal to a piece of electronic equipment.. The current through your switch will be tiny..

What Greg is alluding to, is using a reed switch to switch the actual 'volts' to do something. - Be it a point-motor, or other device..
If you look at the picture of the LGB reed that Korm posted, you will see the inside of the glass envelope has blackened. My guess, would be this has been switching a inductive load (a coil on a point-motor perhaps?). When this is switched 'off' you get a large pulse, similar to how a spark is generated in an old-style car ignition system. Hence Greg suggesting a 'quenching diode' to safely conduct this spike away.
Click to expand...

Exactly, so just straight wiring without diodes will be fine for my application
 
playmofire said:
So, in summary, connect one end of the reed switch to the power outlet in the module and the other end of the reed switch to the appropriate connection (deceleration or stop) in the module.

No need for any diodes as the switch turns on to give a pulse of power as the magnet goes over it and off to cut the pulse as the magnet clears it.
Click to expand...

that depends.
if you got an old fashioned LGB switchmotor, or any other that has three connections, you can asume, that it works on DC.
then you have two cables from two reeds at different positions, that give DC pulse to the switch. (only soft spot with this is a train/magnet, that stops just above the reed. frying your reed and switch.)

the modern AC fed "half DC" switches need diodes. (and they got the advantage, to be harder to fry. because the current is not continuous.)

only if the user has only on/off function, diodes are superfluous. like doorbells or lights. (but then, you still can fry the reed, if your current is high enough)
 
korm kormsen said:
that depends.
if you got an old fashioned LGB switchmotor, or any other that has three connections, you can asume, that it works on DC.
then you have two cables from two reeds at different positions, that give DC pulse to the switch. (only soft spot with this is a train/magnet, that stops just above the reed. frying your reed and switch.)

the modern AC fed "half DC" switches need diodes. (and they got the advantage, to be harder to fry. because the current is not continuous.)

only if the user has only on/off function, diodes are superfluous. like doorbells or lights. (but then, you still can fry the reed, if your current is high enough)
Click to expand...

But I'm not using any switches/points.
 
Korm,

I can't fault you on your knowledge of solenoids or triggering EPL drives, but if he is just fitting reeds to control some off the shelf shuttle module then not only is the traction current irrelevant, but so is the current that the unit draws.

The reeds are likely to carry only a token voltage/amperage, just to allow the internal switching to take place.

If he were powering a solenoid, or an EPL drive it would of course be different.

James
 
Used reeds exclusively and latching relay modules along with rare earth magnets that are incredibly strong. Here are some eBay links you may find useful, only soldering you have to do is for the reeds themselves. I encapsulate mine because the wires are ferrous and soon rust away so I made up a little mold, solder on copper wires to the reed and then encapsulate it in resin. The reeds are quite sensitive and will trip in a fast moving magnetic field.

https://www.ebay.com.au/itm/10pcs-S...783752?hash=item2a394a18c8:g:O3EAAOSwjM5aJNeY

https://www.ebay.com.au/itm/12V-1-C...983399&hash=item41d4ac3896:g:p04AAOSwVqlaEqX-

https://www.ebay.com.au/itm/10pcs-R...173086&hash=item2a6b33c71a:g:TcgAAOSw241YlWwV
 

Attachments

  • Bits 012.jpg
    Bits 012.jpg
    334.8 KB · Views: 0
You must log in or register to reply here.
Back
Top