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Micro switch wiring. Sorted......many thanks.


Mallard60022

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All sorted now; thanks to all.

 

Just checking.

My original set of micro switches, for doing my Electrofrog polarity change via the tie bar movement, have some lettering next to the 'prongs'. I understand  I now know (see below) the frog wire goes to the C 'prong'. However the other two have NC and NO adjacent.

Does this signify anything or can I just solder the stock rails to either one of these 'prongs'?

My next set are Maplins mini micro switches with no letters. Presumably the common is for the frog and the next two for the Stocks?

Thanks; I've not wired this type of switch ever.

Phil 

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On some of my microswitches the common 'prong', that goes to the frog, is at the end. It's always best to check with a meter, or a battery and lamp, before soldering the wires on. You also need to check which of the other 'prongs' is live when the point is switched in each direction, and wire them to the right stock rail, or it won't work.

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Your frog wire should be connected to the C (common) connection.

and NC to the stock rail away from the switch, NO to the stock rail nearest the switch.  Assuming you are using the tie-bar to operate the switch.,

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Usually NC=normally closed, NO=normally open, C=common. Normally meaning with the switch not pressed.

 

Sounds fair enough to me.

 

However, if you're in any doubt, or if you get switches without clear labelling, there's nothing to stop you clipping the leads from a digital multimeter across pairs of terminals - then pressing and releasing the switch lever (or button, in some cases).

 

Most DMMs - even cheap ones - have resistance or continuity ranges - and a short circuit (which a closed switch effectively is) gives you either a very low resistance reading (zero, or very close to it) or beep / buzzing noise. I'd suggest using the lowest resistance range available.

 

 

By the way, I'm not having a go at anyone by saying this stuff. I'm an electrical engineer - and have been for decades - but even I routinely use a DMM to check switches and other components before I wire them up.

 

(It would also be possible to get a few different coloured paint markers - and put a spot of paint next to each terminal, according to some home-brew colour scheme. I don't generally do this myself with switches - but there'd be nothing to stop you doing something like this if it might make life easier for you.)

 

 

Regards,

 

Huw.

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Classic responses and very helpful from you all. I know they were but simple questions but I am very wary of creating trickery mayhem, as you may well know.

My larger, lettered switches are C on one end (by the lever 'hinge') and the unmarked ones are most likely the same with C (common) at the hinge end.

Thanks very much indeed

Phil

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On some of my microswitches the common 'prong', that goes to the frog, is at the end. It's always best to check with a meter, or a battery and lamp, before soldering the wires on. You also need to check which of the other 'prongs' is live when the point is switched in each direction, and wire them to the right stock rail, or it won't work.

BG I think that these switches are all the same by the look of it with common as you say. I had probably not remembered correctly something I had read some time ago and or I've been wiring too many other 'ordinary' switches recently with a green wire to the middle prong :stinker:

Thanks.

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Classic responses and very helpful from you all. I know they were but simple questions but I am very wary of creating trickery mayhem, as you may well know.

My larger, lettered switches are C on one end (by the lever 'hinge') and the unmarked ones are most likely the same with C (common) at the hinge end.

Thanks very much indeed

Phil

A quick check with a bulb will confirm, the unmarked ones are likely to be the NO. I would strongly recommend this or we might get reports of the magic blue smoke escaping. One side of your supply to C one side of the bulb to the other supply then try NO, NC with other bulb wire. Well you did say you were not keen on the 'trickery.
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Picture of subminiature microswitch fitted to points on o gauge layout.

 

post-13054-0-76459700-1459349970_thumb.jpg

 

Orange lead - Common ©

Blue lead - Normally Open (NO)

Brown lead - Normally Closed (NC)

 

Normally as previously posted by djhgreen is with switch arm not depressed.

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Picture of subminiature microswitch fitted to points on o gauge layout.

 

attachicon.gifDSCN0811.JPG

 

Orange lead - Common ©

Blue lead - Normally Open (NO)

Brown lead - Normally Closed (NC)

 

Normally as previously posted by djhgreen is with switch arm not depressed.

Excellent. I'm going to copy that to my layout thread if I may. That's so I remember where it is..........oh dear!

Phil

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When I added microswitches to a collection of points, I made a little device (well, a chocolate block 3-terminal strip) with 3 clips on leads on one side and 3 bulbs on the other, wired to the three different ways. the leads were connected to the frog and the two stock rails.

when I got the switch in position, I hooked the common terminal to the frog and used alligator clips to hook the other to what I hoped were the right rails. I added enough power to light the lamps and checked which position of the switch worked which lamps. If the lamps were wrong, I switched the temporary connections.

When it worked to my satisfaction, I put in permanent wiring.

 

post-6938-0-69354100-1459390519.jpg

 

(well, maybe no terminal strip)

 

post-6938-0-35194100-1459390563.jpg

 

When all worked, I glued a small square of scribed wood to the top of the switch and put it in the hole. The wood was used to hold the microswitch in position and allow adjustment. It could be pinned in position and adjusted again over time.

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Usually NC=normally closed, NO=normally open, C=common. Normally meaning with the switch not pressed.

ALWAYS with the switch not operated, in other words its most likely position, otherwise the terms NC & NO are meaningless.

 

A good rule of thumb for the OP, try to arrange the switches so when the point route is STRAIGHT (or less curved, in the case of curved points!), you wire it so that the common is connected via the NC terminal to the straight stock rail.

 

Another way of ensuring you wire it the correct way around. Set up a multimeter with a continuity tester or a buzzer & connect it across the rails. It it sounds, it will mean that the last wire you just connected, has caused a problem and not a mistake you made an hour ago, yesterday or last time you worked on the wiring!

 

 

A late friend of mine, made the mistake of assuming he knew the layout of some relays & replaced some old handmade switches and without checking as he went. He got it wrong & managed to put a complete dead short across both the Up & Down lines & sidings. The layout never really recovered.

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so when the point route is STRAIGHT (or less curved, in the case of curved points!), you wire it so that the common is connected via the NC terminal to the straight stock rail.

 

Sorry, I'm a bit confused now.......do you mean C terminal via the NC terminal? I thought the C went to the frog? See #4.

Phil 

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so when the point route is STRAIGHT (or less curved, in the case of curved points!), you wire it so that the common is connected via the NC terminal to the straight stock rail.

 

Sorry, I'm a bit confused now.......do you mean C terminal via the NC terminal? I thought the C went to the frog? See #4.

Phil

 

You are now in danger of receiving too much help. Did your crocodile clip method work, if so keep to it.
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Just a thought I standardise as follows

 

Common - Green (frogs in cartoons tend to be green)

Black - Left throw

Red - Right throw

 

All point motors have a number

 

Helps if you have a future wiring fault

 

Terry

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The colours are a personal choice but you need  consistency once you've chosen which are which.   I use Blue for common and any other switched feeds, eg in relays.   Rather than rely on which direction is more curved I tend to work with the railway convention of normal and reversed.  Eg in a signal box if the lever is 'parked' away from the signalman it is set for the normal route, usually the main line and when it is pulled it is reversed, usually for the branch or loop track.   Then NC is always the normal direction.  However as the posters above have said, the terminology is personal choice, as is the colour scheme.  The key point is  a consistent approach and stick to it.   My tortoises are all wired to a 5 way chocolate block with the outer two for the 12v operating current and the inner three for the microswitch, always in the same order so that if I do get a failure it's easy to put n a spare motor.

 

Jamie

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Just to add to the above.  The advantage of the 5 way Chocolate block is that when it's been installed you can test the point with a meter to see whether the frog is connected to the correct stock rail.  Then it's just a matter of swapping one feed wire to the chocolate block.

 

Jamie

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so when the point route is STRAIGHT (or less curved, in the case of curved points!), you wire it so that the common is connected via the NC terminal to the straight stock rail.

 

Sorry, I'm a bit confused now.......do you mean C terminal via the NC terminal? I thought the C went to the frog? See #4.

Phil 

No, that isn't what I meant. The C is always Common & goes to the Frog. The NC is connected to the straight rail.

 

As has been suggested, it actually easier to understand, once you actually start the wiring.

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Thanks everyone. I have begun installation and they are all working so far. I am testing each one as I go, with a loco, using DC!

As I only need three wires at the moment (the points are hand operated just for now) I am using extensions from the feeds from the stocks (red or orange & black or grey) and the green for the frog. There are a few I could link to surface mounted, converted Fulgarex sometime in the future but only if the Fiddle Yard, where these switches are being fitted, works as I want it.

Phil

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