Back to points wiring

[LAGBAG]

can I put wires from controller direct to track from auxiliary output and wire points direct to track at each location as when you read the select operations it says you can control several solenoid operated units I have read some of the blurb re wiring on this forum and it conflicts with   my understanding

[Chrissaf]

No you can't wire it up as you suggested.

.

The AUX output of the Select is 15 Volts DC at relatively low current. If you connect this output to the track, then you are likely to damage the DCC side of the Select as the DCC signal must never come into direct contact with a DC or AC AUX output voltage source.

.

You can still use the 15 volts AUX output of the Select to manually operate Solenoid point motors with electrical switches but only if you include a CDU (Capacitor Discharge Unit) between the Select AUX output and the point switching cicuits. The AUX output is very low current and not enough to operate a Solenoid point motor directly in a robust manner.

.

Solenoids have very low impedance and look for all 'intent and purpose' like a 'short circuit'. If you try and use the Select 15 volt DC AUX output to directly operate the solenoid, the current draw will be far too much and the DCC side of the Select will most likely be affected. There are posts in this forum where this has been reported to be the case and that fitting a CDU has solved the issue.

.

The CDU stores a high electrical charge. It is trickle charged from the low current output of the Select AUX output (never connect the CDU to the track output of the DCC controller), but is able to provide a very high current kick of several amps to robustly operate the solenoid point motor. When a point is operated, the CDU recharges again typically in about 2/10ths of a second ready to operate the next point. Hornby do not make CDU's but they are cheaply available from all good model railway product retailers. An example of a CDU.

.

Note: Since this schematic is taken from my image library it shows up to 12 PECO branded Solenoid point motors, but these can be any branded Solenoids and more than 12 motors if needed. Note that the electrical point operating switches shown are not Hornby's R044 point switch. The R040 switches are not 100% compatible for use with a CDU. The SPST (change-over) electrical lever switches shown in the drawing must be 'momentary in action' with a 'sprung to centre off' position. Switches of this spec are readily available from the big online model retailers and also from niche suppliers on ebay.

.

/media/tinymce_upload/49cb4bbdad68e12962555a8d88897c0c.jpg

.

The other way of controlling points using a Select is to use DCC commands via the Select DCC control interface. In this scenario you utilise an Accessory Decoder. The Hornby R8247 Accessory Decoder has four ports typically with one point allocated per port. Multiple R8247 decoders can be connected to the Select up to a realistic maximum of 9 to control up to 36 decoder ports. A 10th R8247 could be added but you could then only use two of the four ports.

.

In this scenario, you do not use the Select 15 volt DC AUX output at all.

.

In which case it would be wired akin to this:

.

/media/tinymce_upload/d187527c6468ece9817777fa034353e2.jpg

.

TIP: As this is your very first post, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button.

.

Particularly as my reply includes images. If you use the blue button, any reply you write, may be held back for image approval. Even though it is already a previously published image.

.

See also – further TIPs on how to get the best user experience from this forum.

https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/

.