I have four of these track switches that I'm going to use at both ends of two separate shuttles. I bought them for using as a regular Reed switch. Here's my problem. When I check continuity on the terminal block common to normally open, normally closed to common, etc. I get no reading on my multimeter but when I check on the actual glass Reed switch it works fine with the magnet. Does anyone know why I can't get continuity on the terminal block with a magnet? Thank you in advance
17100 LGB track switch
- Thread starter geoffreym
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You do realise these are used with AC?
Copied from Shourt Line..
Obviously, we in the UK would use a transformer with a 240V primary..
Your meter uses a battery (which is a DC power source. The diodes only allow current to flow in one direction. This means you get a reading between 'common' and one of the other contacts when the switch is activated AND you have your meter probes the correct way round.
PhilP.
Copied from Shourt Line..
Obviously, we in the UK would use a transformer with a 240V primary..
Your meter uses a battery (which is a DC power source. The diodes only allow current to flow in one direction. This means you get a reading between 'common' and one of the other contacts when the switch is activated AND you have your meter probes the correct way round.
PhilP.
First of all, thank you for your help. It's appreciated. I might be a bit over my head here but I did try reversing my leads and still can't get any kind of continuity. Is there something else I should be doing? The reason I'm checking continuity on this terminal block is because I want it to switch when my street car goes over it with the magnet basically a simple read switch that switches to ground. These LGB switches were expensive and I'm hoping I can use them somehow
No problem..
These switches are normally used with an AC supply. AC has both positive and negative half-cycles. This is normally fed into the centre (common) contact of the switch.
When activated by the magnet, the switch is closed and the AC is fed to the diodes. The 'top' diode let's the positive half-cycles through, and the bottom diode let's the negative half-cycles through.
A diode will only let current flow in one direction.
You will use the common contact, and one other only.
You will not see any continuity on your meter, unless the switch is activated by a magnet.
If you leave your meter connected to the common connection, then activate the reed with a magnet, you should get continuity to one of the other pins.
If you swap the meter lead to the common terminal, activate the switch, you should see continuity to the other pin.
PhilP.
These switches are normally used with an AC supply. AC has both positive and negative half-cycles. This is normally fed into the centre (common) contact of the switch.
When activated by the magnet, the switch is closed and the AC is fed to the diodes. The 'top' diode let's the positive half-cycles through, and the bottom diode let's the negative half-cycles through.
A diode will only let current flow in one direction.
You will use the common contact, and one other only.
You will not see any continuity on your meter, unless the switch is activated by a magnet.
If you leave your meter connected to the common connection, then activate the reed with a magnet, you should get continuity to one of the other pins.
If you swap the meter lead to the common terminal, activate the switch, you should see continuity to the other pin.
PhilP.
korm kormsen
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to understand how these work, it would be good to read the LGB manual. (starting at page 113)
it is no rocket sience. once understood, it is simple.
main rule: DON'T USE WITH DC! - they are made to work on AC. (explained in the manual)
(i use an 16V AC transformer)
about these reed switches being expensive...
once understood the way, they work, everybody could fabricate his own from cheap parts. (everybody, even me)
lately i tried out an even easier way. using reed switches from alarm systems plus diodes. (it seems to work, but i still have to learn, for how long they last)
it is no rocket sience. once understood, it is simple.
main rule: DON'T USE WITH DC! - they are made to work on AC. (explained in the manual)
(i use an 16V AC transformer)
about these reed switches being expensive...
once understood the way, they work, everybody could fabricate his own from cheap parts. (everybody, even me)
lately i tried out an even easier way. using reed switches from alarm systems plus diodes. (it seems to work, but i still have to learn, for how long they last)
Is there a way I could modify this switch to work with my mCP 23017
korm kormsen
Registered
OH!
i don't even know, what a "mCP 23017" is.
i'm no electronics engineer, but only a third world hillbilly trying to keep his trains running.
untill now i used the reeds only in connection with the LGB - epl switchmotors and its addition.
but i'm sure, that there will be somebody else here, who can answer that.
It sounds like you have a lot of knowledge and history about trains. I am just getting into it so I think you're far ahead of where I am. It's just I'm using some new types of controllers
korm kormsen
Registered
a lot of knowledge - that's a clear NO. i just remember most of what did not work on my layouts.
history - x-mas 69 or 70 i got my first LGB set. since then it grew with pauses and on shoestrings. now i am (slowly) preparing the hobby room for my 5th and last "permanent" layout.
all these years i stayed stuck on automated layouts on analogue DC.
if you think, that i'm ahead, i'll castigate you with some unsolicited council: do, what you like. the only person, that really has to be pleased by your model railroading is you yourself.
if others don't like it, they can build their own.
Software Tools
Registered
If you just want to detect a simple ~5V DC contact closure (due to the proximity of a magnet) the it would be best to bypass (wire across) the diodes in the 17010.