Adding two aspect signals

[Padders]

Having re-organised my points accessory decoders, I am now looking at adding 2 aspect signals. The manual suggests I can wire these to the solenoids (page 80) but I thought the points were driven by a short burst voltage from the controller.

I want to add red and green LED’s for the signal but these would require a constant (switchable) supply voltage.

Does anyone have a circuit diagram of how to consolidate the signals with the points without adding a separate decoder?

[P-Henny]

I suggest that you have misinterpretated the text on Page 80. There is nothing on Page 80 that remotely suggests that you actually wire the signal in parallel with a Solenoid point motor.

The only reference to Solenoid point motor wiring relates to reversing wires if point and signal are out of sync.

The actual example in the image on Page 80 is based upon using a Train-Tech signal that has its own dedicated integrated DCC Decoder built into the product.

The essence of the RM manual Page 80 text is based upon the point & the signal each having their own decoder and using the Railmaster software to synchronise their operation.

If you want to sync a dual aspect signal to a point without using a separate signal decoder port, there are only three basic options.

• Option 1) Use a point decoder that has a built in changeover switch contact. For example Accessory Decoders made by DCC Concepts or other suitable non-Hornby brands. Not possible to do with Hornby's R8247 Decoder.
• Option 2) Piggy back a mechanical changeover metallic contact switch to the Solenoid point motor. For example a PL-13 switch made by PECO. Only suitable for Hornby R8014 & PECO PL-10 underboard point motors. The switch has to be glued onto the point motor and needs very careful alignment. Speaking from personal experience as this is my installed solution. If I was doing this again I would be going Option 1) on a new build or Option 3) if Hornby Accessory Decoders were already purchased.
• Option 3) Wire a Guagemaster GM500D latching relay product in parallel to the point motor. The pulse operates the relay, but it latches to give a permanent switch contact connection.

The wiring diagram for The GM500D is published on this following webpage:

https://www.gaugemasterretail.com/media/downloads/GM500D.pdf

In all three options above, the dual aspect signal is wired (via its own dedicated separate power supply) to the metallic changeover contacts.

[96RAF]

Grabbed from the R8247 manual. Try the fourth one.

[P-Henny]

Noting that 96RAFs 'Fourth Image' is the same solution as my Option 3) GM500D option.

[Padders]

Thanks All

Sounds like the GM500D is the best and most cost effective option.

As I'm running miniature LED's and have several crossover points, is there a current(mA) limit on the number of signals I can change using a single GM500D?

i.e. Put a program together where several points are changed for a particular route using a single GM500D for signalling, I could then plan serveral routes employing a specific GM500D for each route rather than one for each set of points and keep the cost down.

(couldn't find any current (mA) data in the pdf Paul linked or by trawling the web for tech specs)

[96RAF]

The 500D is essentially a latching change-over relay with the signal and frog current going thru’ the main contacts, so no real current limit beyond what your signals require. As Paul says each pull in coil is operated by a pulse from your accessory decoder and again current limits can be ignored due to the brevity of pulse duration.

[P-Henny]

The contacts on the GM500D are rated at least 1 Amp and probably more. There are also two separate changeover contacts on the GM500D thus the number of concurrent LEDs can be split 50/50 across the two changeovers (assuming you don't need to use the second changeover contact to power electrofrog point frogs).

A typical LED will be 20mA and with an appropriate resistor as low as 5mA. But at 20mA consumption, this equates to 50 x LEDs per 1 Amp of switched current.

So a GM500D could potentially switch 100 x LEDs if the contacts were 1 Amp rated (50 per changeover contact) or 200 x LEDs if contacts rated at 2 Amps. And even more if the LED current is less than 20mA.

This is a long winded way of saying that in principle you shouldn't need to be too concerned about how many concurrent signals the GM500D can switch as the switching current is handled by metallic relay contacts and not switched by semi-conductor circuits.

EDIT: The lack of brevity in my reply accounts for why 96RAFs reply beat me to being published.

[Padders]

Brilliant

Thanks Paul and RAF great advice and response once again.

Regards

Martin

[P-Henny]

Update to my previous reply.

The GM500D latching relay for Digital uses the exact same relay as the GM500 latching relay for Analogue. The GM500 instruction manual states that the contacts are rated at 2 Amps.

https://www.gaugemasterretail.com/media/downloads/GM500instructions.pdf