Route indicator unit query

[David Rickard]

I've been doing a lot of digging today, and reading up on stuff. I want to be able to switch my points, indicate the route I've selected, and switch the polarity on the electrofrogs. Unfortunately when I bought my point motors (Seep PM2 - i.e. without the switch built in) I'd not appreciated that it's good practice to wire up the eletrofrogs and switch polarity. I thought I'd be able to build some sort of circuit to do it, but it was getting increasingly complex with what I wanted.

 

Then I found this: http://www.heathcote-electronics.co.uk/PtIndicr.htm#POINT%20INDICATOR-RELAY

 

It's exactly what I wanted! However, I'm mildly curious if anybody has any prior experience of these units, and what they think of them. Does anybody know of any alternatives? They're about ??22 each, and I'm going to need three, plus two of the slighly lower-end model which doesn't do the relay switching for my fiddle yard (it uses insulfrog points), so I'm keen to look at options.

 

Replacing the point motors is of course an option, but I think it'll add a lot of wiring, and having to build a small circuit for each point anyway to indicate the route selection (nothing more than a couple of diodes and some resistors, but still). Could end up as broad as it is long. I just don't like the idea of having left-over point motors for no real reason.

[Edwin_m]

Not used anything like this myself but I'd be a bit cautious about retro-fitting them to unmodified Electrofrogs. This is because the circuit will switch the frog polarity almost instantaneously whereas the motor will take a little time to operate (or occasionally may not operate at all). If that happens and the switch-stock rail junction is conducting then the result will be a short circuit. Potentially an annoying intermittent fault (and the thing about intermittent fauls is that they disappear when you try to trace them!).

 

This may be tolerable in DC, especially if you don't switch the point when there is power on the track section in question, but could be a real pain in DCC. To do the job properly you need to electrically isolate the switch rails from the frog and electrically connect each one to the adjacent stock rail.

[David Rickard]

Not used anything like this myself but I'd be a bit cautious about retro-fitting them to unmodified Electrofrogs. This is because the circuit will switch the frog polarity almost instantaneously whereas the motor will take a little time to operate (or occasionally may not operate at all). If that happens and the switch-stock rail junction is conducting then the result will be a short circuit. Potentially an annoying intermittent fault (and the thing about intermittent fauls is that they disappear when you try to trace them!).

 

This may be tolerable in DC, especially if you don't switch the point when there is power on the track section in question, but could be a real pain in DCC. To do the job properly you need to electrically isolate the switch rails from the frog and electrically connect each one to the adjacent stock rail.

 

Oh I see. That makes sense. Despite the fact the connectivity on the blades is supposedly pretty bad, I can see a situation where the frog switches, but it IS making contact with the rail, and thus shorts.

 

Looking at the points (they're Peco Streamline), I'd need to disconnect the feeder wire underneath which runs from the frog to the blades. and replace it with two wires going to the outer rails. Thing is, there's some rather fine soldering there, and I'll just end up destroying the points.

 

My controller has short-circuit protection - I've shorted out stuff enough times, so it should be OK. I think!

[Edwin_m]

Some types of Streamline points have links underneath that allow these changes to be made quite easily - I think Code 75 does and code 80 or 55 N gauge certainly don't.

[David Rickard]

These are 55 N