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Reply to "The RR Track Signal Control Board Project"

stan2004 posted:

Perhaps you've got it all figured out or found a similar diagram, but if using the 3PDT contacts strictly for driving the LED signal heads:

3pdt block signaling

For N signal heads on consecutive/adjoining blocks, you need N+1 relays.  The leftmost relay can be a DPDT type.  The rightmost relay can be a SPDT type.  All relays in between are the 3PDT type.  Or, use all 3PDT types and no need to make some connections on the leftmost and rightmost relays.  Example above has 3 signal heads requiring 4 relays.  I drew the wiring to each signal head separately to illustrate how the wiring "pattern" to each signal head simply repeats.  If drawn all together it would look like a mess! 

If you're messing around on the bench, you might look into placing a 25 cent resistor-capacitor filter on the DC relay coil contacts to demote chatter.  That is, when a consist enters/exits a block, the lightweight wheel axles (e.g., pilot truck on a steam engine or trailing truck on a caboose) may make intermittent insulated-rail contact causing the LED signals to flicker.  I'm pretty sure Dale covers this ... or I can elaborate if this is of interest.

Stan2004:   So I am well into building a central relay panel with 24 of these 3PDT relays.   It took a long time to finish and connect the 240 foot main line.... that happened this past November 2019.   

I decided to use this signal control scheme for the entire main, so I have created 11 independent blocks, and have installed 24 relays,  12 for eastbound,and 12 for westbound signal control.   As of tonight,  the 12 relays are wired for "eastbound travel",  I will start bench testing this tomorrow 1/22

My question Stan:  I am not sure whether I need 11 relays and 11 signals or 12 relays for the 11 blocks/11 signals.  My blocks are alpha labeled A through K... when the train leaves K it enters A ( continuous loop)....

I know it's been 15 months since you helped me out but if you bump into this thread, maybe you could provide some insight.  

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