As promised, Rob, here’s a round-up of how I would do it; I’ve tried to be as brief as possible.
As you’ll find, I’ve punctuated my waffle with pictures which hopefully will explain it all better than I can.
Before I start, I’d submit that simply wiring the point motors straight to your choice of activation (studs and probe, as kindly suggested by Nigel, or switches of some sort, my own choice) does not, in theory, require the addition of a CDU (capacitor discharge unit) as there should be sufficient ‘clout’ provided by the controller to successfully switch them (usually, you’ll find that with say five or more point motors, there isn’t sufficient force to move them all, and instead of a successful switch from one side to the other, you get a mere twitch of the blades and a rather sorry sounding click).
However, despite the Twistlock being the latest offering from Peco, it’s still a plain ol’ solenoid motor, accompanied by the age old risk of burnout - a pain generally, but Twistlocks don’t come cheap as you’ll have discovered, Rob - so for the sake of less than a single Twistlock motor, it makes sense to safeguard your investment with the presence of a simple CDU. Lecture over.
I suspect that the mention of CDU probably fills you with fear and prevents you from reading this diatribe any further, but if you bear with me, I’ll demonstrate (with pictures) just how easy they are to install. In practise, you just wire the choice of operation - e.g.studs, probe etc. - straight to the switches, as mentioned earlier, but install the CDU between the two, which provides sufficient force to do the job whilst preventing any harm coming to your expensive motors.
They’re not essential in your case, Rob, as mentioned, but just in case I’ve persuaded you, I’ve previously used cheaper options available from the likes of eBay:
BLOCKsignalling is a professional manufacturer of model railway electronics accessories based in. This sale is for a high power CDU designed for all manufacturers' points motors. Limits subsequent points current to prevent coil burn out.
www.ebay.co.uk
As mentioned, I prefer to use switches to do the job as I like the look of them on my control panel. You can use the passing contact switches from say Hornby, but they’re not cheap and cannot be accommodated on a panel as easily as smaller switches that I use. An alternative, is to use a push-to-make switch(they work as their title suggests) which can also be accommodated on a control panel and are cheap to buy. Any risk of burnout by depressing the button longer than required is negated by the presence of a CDU as discussed.
However, I prefer to use a momentary toggle switch or ‘centre-off’ switch:
Quite simply, they’re an on-off-on switch containing a spring which returns it to the centre off position after switching them up or down (on-on) which switches the points. As I’ve harped on, it doesn’t matter how long you hold the switch in the on position as the CDU (if present) prevents it from burning out the point motor.
The base of the switch has three prongs or contacts as seen above, to which three wires will be attached, more of this soon.
To business.
Take two wires from the AC output on your controller (usually on the rear of the casing). There are designated AC controllers about, but for simplicity, let’s pretend we’re using a basic method of powering the layout:
Let’s label one wire ‘positive’ (I’ve used brown for this as I was using up old wire which I didn’t want to waste) and the other ‘negative’ (blue in my case).
Here’s a picture of the brown (positive) and blue (negative) wires from the controller on the underside of the baseboard coming in (horizontally) from the right as we look:
The brown and blue are then connected (via choc-bloc connectors, their use recommended to reduce strain on the connections to respective appliances in the event of mishandling, important on an exhibition layout, perhaps not as vital on a home layout) to the CDU:
(don’t worry about the sequence of wires in and out of the CDU as each comes with its own easy to read diagram of where these go).
So, I think the conundrum at this point is: how do two wires ‘in’ from the controller (via CDU) become the three ‘out’ from the point motor?
It’s best to think about this by discounting the two ‘feeds’ from the controller/CDU for now, and comparing them to the three contacts protruding from the base of the centre off switch I use and shown above. We’ll come back to the three-become-two issue a little later.
So, looking at a single Twistlock, there are three coloured wires protruding: two green, one red, one black. Connect the three coloured wires individually to a choc-block connector (the two greens just go into one), so that there are three choc-bloc terminals as shown (lower right of picture):
In the above photo, I’ve used blue coming from the black wire, and brown emanating from the red wire. You can ignore the yellowy green wire for now.
Do this for each of your three Twistlocks.
The next step is to connect the black wire of the Twistlock to one of the outside terminals or contacts of the centre off switch using corresponding coloured wires which help, and which I didn’t! Connect the black wire to one of the outside terminals on one side, and the red wire of the Twistlock to the outside terminal on the other (it doesn’t matter which of the outside terminals are chosen for red or black for now- the switch will throw the point blades one way or t’other, and if they don’t correspond to how you want them to work with your switch or vice versa, just change them round later).
Here’s a switch or two (the switches with black bases) wired with the outside terminals in corresponding blue and brown wires:
Please ignore the centre yellowy green wire (I should have used an entirely different coloured wire altogether, as it is easy to confuse this with the yellowy green wire emanating from the green wire(s) of the Twistlock shown in the earlier photo…).
Now, we’re left just left with the green wire(s) choc bloc connector from the Twistlock, and which you might reasonably guess from what I’ve just written, would go to the remaining ‘centre’ terminal of the centre off switch.
Only, it doesn’t!
So, hoping you’re still with me at this point, we now address the next part of the conundrum: how to add power to the Twistlock point motor(s) from the controller/CDU (the two-become-three bit), and this is where the green wire(s) from the Twistlock comes in.
To start, here’s a picture of my own (I’m referring to the the yellowy green wires from the two Twistlocks shown):
but I think the congestion of wires below board here, together with the non-corresponding use of different coloured wires, doesn’t help, so just in case, here’s a broken down diagram found during a search which should help (?) to illustrate what I am about to describe, more clearly:
Essentially, one of the feeds from your controller/CDU (again, doesn’t matter which, positive or negative) goes to the green wire(s) choc-bloc connector of your first Twistlock (I’d use the same green coloured wire to make it easier to identify).Then, take a same coloured, let’s call it ‘green feed wire’, and connect it from the green wire(s) choc-bloc connector of your first Twistlock, to the green wire(s) choc-bloc connector of your second Twistlock. Similarly, take a green feed wire, and connect it from the second Twistlock to the green wire(s) choc-bloc connector of the third Twistlock.
All three are now fed with one of the two feeds from the controller/CDU.
So, how do we complete the circuit by connecting the second of the two feed wires from the controller/CDU?
Well, this is where the third (middle) and final terminal or contact of the centre off switch comes in.
So that all three Twistlocks are powered, simply run a wire in series (as it’s known), in other words, just take the wire from the middle terminal of the first centre off switch (as just mentioned and shown in the above diagram) and link it to the middle terminal of the second centre off switch and then the third in turn (as we did with the green wire(s) of each Twistlock), and then finally connect it to the second feed of the controller/CDU.
Not sure whether it helps, again for reasons of congestion below board, but in the above picture (I’ll show it again for ease), you might just be able to make out that I’ve used the positive (brown) wire from the CDU to connect to the middle terminals of the centre off switches as described, but as I was running short at the time, I’d switched the brown for yellowy green wire by the time it reached the switches, hence the yellowy green wire shown connected to the middle terminal wire of the switches in the earlier shot of the rear of the control panel:
Incidentally, the ‘other’ yellowy green coloured wire connected to the blue (negative) wire of the feed from the CDU, is the one that runs to the green wire(s) of each Twistlock.
And that’s it, Rob.
I hope it helps but let me know if I can clarify any of the above.
Good luck which ever method you choose.
Jon