... or perhaps an electrical miracle. Or more likely I'm losing my marbles. ::)
I'm wiring point motors using Gaugemaster passing switches. The feed is from the controller to copper tape and then into five separate banks of switches with a single copper wire linking all the centre contacts on each bank.
I'm getting a meter reading at all relevant points on four of the banks but on the fifth one I'm getting a reading at the first switch and at the last switch and nothing on either switches or wire in between.
Since my limited knowledge of electrical circuitry tells me this is not possible ..........
You are connecting one of the outputs from the CDU (or supply) tothe centre terminal of each point motor (so all of those centre pins are ganged), and the other output from the supply to the centre terminal of the switch ganged to the next centre switch's pin? Then from the switch to the correct coil on the motor... Apart from resistance, in theory you could go on infinitum.
Strange....
Sounds like dry joints on the contacts
Thanks for the replies.
Bealman; that's my reading of it. Provided my connections are good I could in theory have connected the whole lot end-to-end and halfway down the street!
Malc; If there was a contact problem I would have expected a complete dead "branch line" after the first contact. There are five contacts all connected with the same wire. The first is live; the last is live; the three in-between aren't. I don't understand how this is possible.
If I've discovered the secret of "radio-electricity" I'll patent it and make a killing. However I suspect there is another explanation.
As I understood it, you have 5 contacts in parallel. I assume you are using insulated wire to connect them together. If the first is live and the last is live, it must be the connections on the middle 3. ie dry joints where they are soldered. If this isn't how it is wired, maybe a little sketch would help.
It's bare wire which is why I couldn't fathom what was happening. I should have made that clear in the original post.
I've now stripped out that section and replaced it with steel wire which has solved the problem but I'm still puzzled.
Was the wire you replaced multistrand or single core? If it was the latter, there could have been a break somewhere, or it might still have been a dry joint at the ends. Definitely puzzling, but if it works now, as they say, don't fix it! :thumbsup:
George
Multistrand, which was another reason for the mystification. I wasn't even getting a reading off the wire itself in-between the first and last switch. Weird!
"Back to Square One" was always going to be the solution so onward and upward from here. Thanks for the replies.
It's buggin' me though. If you find the cause, please pm me... I would be interested! :thumbsup:
The acid test would have been to cut the wire in the middle and see if the last switch still had power. However, having fixed it......
The problem seems to be something to do with the copper wire though not all of it.
On another branch (track feed) I get a good contact up to the point where I've soldered the (steel) wire from the controller to the (copper) wire at the contact on the first switch. In this case I'm using SPDT centre off switches with the track feed from the centre contact and the outside contacts feeding from the controller(s). One works fine; the other doesn't.
And yes, I do have a good join between the two wires at the switch.
I'm also having trouble getting the copper wire to take solder at all, even using flux. Could this be relevant?
Quote from: Frenchie on July 02, 2014, 03:35:39 PM
I'm also having trouble getting the copper wire to take solder at all, even using flux.
Sounds like you need the soldering iron hotter.
Is your copper wire the normal sort, covered in a plastic outer sheath, or is it all nice and shiny on a reel? If it is the latter, it is covered in a very thin layer of lacquer that needs to be removed before soldering. I usually burn it off with a cigarette lighter before soldering.
:claphappy: :thankyousign:
CRACKED IT! Thanks, Malc
Probably also explains why I was getting random contacts on the switches and no contacts on the wire. I seem to remember (now you mention it) something about lacquer on copper wire but since I've never used it before it never crossed my mind.
Obviously a lack o' knowledge on my part.
I'll get my coat. :-X
The lacquer is used as an insulator, just like the plastic coating. Glad you've sorted it out. Stops all those sleepless nights.
Good on ya, Malc! You're the stuff of legends, mate. :thumbsup:
George
It's an easy mistake to make George. We used rolls of this stuff to make coils for specialist short wave radio receivers when I worked for the a World Service, otherwise you don't often come across it. When I moved into TV, we made equalisers using tinned copper wire for links. It was a good trick to swap a reel for one of steel wire and watch someone burn their fingers trying to heat it up enough to solder.
Thanks, Malc. That is so interesting to bloke that as a teenager used to delve under valve radio chassis! Often to his misfortune... amazing I'm still here! :thumbsup:
Steel wire.. that'll do it! >:D
George