Need circuit to use a Digitrax BDL168 for Lionel AC Block detection

Did Digitrax say WHY it would not work?

I'm not familiar with that product but 2-rail systems generally use current sensing to detect occupancy.  Perhaps their current sensors are configured to only detect high-frequency DCC as opposed to low-frequency O-gauge 60 Hz AC?

IF such is the case I'm imagining using a high-frequency signal from a $2 eBay 555 timer module.  This isolated signal could be piggy-backed onto the AC track power and a 5 cent resistor in each block would draw high-frequency AC current when the axle(s) straddle the outer rails.  Note that the actual hi-frequency current can be quite small since the 2-rail method can have simple resistors within a rolling-stock axle as a detectable load current.

Alternatively in the same way a 3-rail isolated section can activate a relay for signals, it could activate whatever type of electrical load the Digitrax current sensor requires.  This would probably require a relay or some kind of switch (e.g., transistor) for each block.

Stan2004,

They did not say why.  I believe it does current sensing and I believe it its rated for 3 AMPs.  Would the high frequency signal work with Legacy or would I be better of with just having it trigger a transistor? 

Thank for your suggestions.

Well, if the WHY is because exceeding 3 Amps (as you would in O Gauge) overloads their electronics, renders it helpless, releases magic smoke, whatever then that's a different issue.

I am merely speculating (out of ignorance) about a hi-frequency requirement in their current sensing mechanism.  The Legacy/TMCC signal frequency is over 10 times higher than the DCC frequency so I do not think this would be an issue if you had to add such a signal to trigger the Digitrax sensors.

In any event, if the hi-frequency is required, my idea of a low-cost eBay oscillator module is simply to remove the need to dedicate an expensive DCC power booster if its sole purpose in life is to generate a hi-frequency signal!

Hopefully someone who knows the Digitrax sensor characteristics/requirements will chime in.  Otherwise, I guess there are some experiments you could perform but seems like that would be re-inventing the wheel.