The PL15 is attached to the PL10 so it has to move that as well as the point blades. That's what I was referring to as linkage. I've had several cases of sticky PL10s where removing the PL13 allowed the point then operate freely - hence I've been looking for alternatives. I also had a few cases where I wanted a DPDT switch on a single point to aid some signal interlocking.
I'm not familiar with electronics and have never used a relay before, but I needed to do so to operate some new colour-light signals using DCC control via Lenz LS150s. I was advised to use a latching relay from Maplins but at £3.73 seemed a tad expensive, and instead purchased a Hongfa HFD2 relay for £2.50 off Ebay where the postage was only £1. Subsequent trawling through the internet found JPR Electronics selling these for £1.25 + VAT. With a bit of stripboard, an IC socket, some terminals and diodes total cost was £2.50 for which you get a DPDT switch. Apart from the signals I have used the board to replace pairs of PL13s on crossovers, as that increased reliability of the PL10s and also meant absolutely precise installation is no longer paramount. The relay is simply wired in series with one of the point motors. So far the PL13s I've sold on Ebay have realized about £1.25 each!
Here's a picture of the first board I built. There are 1N4004 diodes between the + and - feeds from the LS150 on the top, and to the common return at the bottom. 1N4001 diodes should be OK though. I've subsequently connected the two bottom terminals together so only one diode was used instead of 2. The ring on the diode indicates the cathode and you need to ensure it's the right way round.
If you are using a non-latching relay and are supplying 12V DC then you don't need the diodes. There are also only two connections - ie you supply constant DC power to switch the relay one way and remove it to reverse that. Here's the datasheet for the Hongfa HFD2 - latching and non-latching versions. The Maplin version is similar - datasheet on their web-site.
http://www.wwb-st.com/002/HF/HFD2.pdf
As regards postage costs then it's £3.95 from JPR Electronics but that is waived if the order is more than £30. For me to go to Maplins is a 20-mile round trip + parking - probably around £3.50. Then I have to pay Maplin's prices as well, so buying from the internet is far cheaper.
