Anyone use psc signal parts and custom signals boards for integration?

Hi PRRHorseshoeCurve,

I have not specifically done what you are asking but I have done a lot with signals.  The Custom Signal Systems boards just drive LEDs installed in their own signal heads.  I assume you are planning to use LEDs in your home brew signals as well.  All you need to do is match up the polarity of LEDs on your home brew signals with way the Custom Signal boards output to their LED signal heads (common anode '+' or common cathode '-') and you should be good to go.  You will also need to see if they provide the dropping resistor in their board of if they expect the installer to put a dropping resistor inline with each signal head LED - I'm sure LED polarity and if there will be a need to add an external dropping resistor would be spelled out in the Custom Signal Systems instruction sheet. 

It does not look like Custom Signal Systems supplies an occupancy detector so that piece is up to you to select from a 3rd party.  I personally like Bruce Chubb's current-sensing OD [Optimized Detector] (for analog DC) or the DCCOD [DCC Optimized Detector].  They are highly sensitive (sensitivity is adjustable too to correct false occupancies), robust enough to use for O Scale and can be assembled by yourself, if you wish, to save some $$$.  Both the OD and DCCOD output a logic low signal when active, so Custom Signal Systems can design their signal logic for that input (that is probably their standard occupancy detector input signal anyway).   

Hope this helps...

Scott Kay

Austin, TX

Thanks for the advice. Yes custom signals uses a common cathode LED system.however their inventory is lacking in many position light signals. Now I have some Shiloh signals that I want to integrate too but Shiloh uses a common anode and with a diode. By your response I will have to strip the Shiloh signals down to bare casings and construct new electronics for them to be compatible.

Just a FYI - in years past Mark at Shiloh would build to order and reverse the polarity of his signals - not sure if he still will do this.

Hi PRRHorseshoeCurve:

If you want to salvage the Shiloh signal heads, you can use a circuit just like the one in the link below: 

http://www.ermicro.com/blog/wp...s/2008/12/trsw04.jpg

Basically, a resistor ([RB] - Resistor base) and a 2N3904 NPN transistor (used as a switch) is all you need.  It takes a logic high output from a micro controller port and converts it to a logic low at the transistor "collector" terminal.  Otherwise, known as an "open collector" circuit.  When the micro controller port output goes high, the 2N3904 transistor is energized at the base through the R Base resistor (you need to calculate this Rb - see bottom of description below) to control the saturation current flowing to the transistor.  When the base of the transistor gets saturated, the "collector" terminal is connected to the "emitter" to form Collector-Emitter circuit to ground.  Therefore, the "collector" terminal is basically very close to ground or 0 volts and the current now flows through the LEDs to ground to illuminate the LEDs.   When the micro controller goes logic low, the transistor collector / base circuit is basically open, and no current flows through the LEDs since their circuit is not complete or open and  LEDs do not illuminate. 

Use a resistor on inlet to the LEDs to regulate the current flow to the LEDs so you don't turn them into onetime-use flash bulbs.  LEDs generally use about 20-30 mA of current with about a 2 to 3 volt drop.  Therefore this LED resistor (they have it labeled Rc) can be calculated using Ohm's Law I = E/R.  We want to solve for R, so R = E / I.  E = LED power supply voltage - LED voltage drop.  For an example, let's say you have a 12 volt supply for the signal LEDs and the voltage drop across the LED is 2.5 volts, and the LED uses 20 mA or 0.020 Amps of current.  Therefore, R = (12 - 2.5) / 0.020 or R = 475, we can then use the more commonly available 470  ohm 1/4 watt resistor for Rc.  If the LED burns too bright, then you can use a higher value resistor to dim the LED brightness to taste.  If you don't know what the LED voltage and current ratings are, start and 1K ohms and work downward until they illuminate to taste.    

The total component price for this circuit would be less then a 10 cents each.  You will have to make this resistor/transistor circuit 3 times for each position light signal head (vertical, horizontal, and diagonal).  You can build it on a piece of perfboard prototyping board (you can find these on Ebay pretty cheap).

To do the math to determining the the RB resistor value for the transistor, you can use the link below and scroll down to the "Using 2N3904 Transistor for Driving 5 LEDs" picture.  Just below that picture (which is actually the link to the picture in the first link above) is the math part that you can follow to determine the RB resistor values for your specific application.

http://www.ermicro.com/blog/?p=423

 The unknowns at this point are the Custom Signals output logic high voltage and the power supply voltage you wish to use to drive your signals heads.   Note that the power supply voltage for the signals does not need to match the supply voltage of the Custom Signals boards or their logic output voltage (you can use the same supply for both if you want); however, you must tie all the grounds together if using different supplies, even if they are same voltage.  I would also recommend that you use a filtered and regulated power supply for both the Custom Signals boards and the signal head LEDs.  Again, you can find these 5Volt, 12Volt, etc. or even multiple voltage switching power supplies of various current ratings 3, 5,10 Amp, etc. pretty cheap on Ebay.

Hope this helps....

Scott Kay

Austin, TX