rtr12 posted:...
I also like the idea for the power shut down function. This might also be appealing to some folks here. Might be in for trying that one myself. Regardless of project interest, I do enjoy all this, always learn something along the way, get a new circuit design and have something new to fiddle with after samples are assembled.
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I found the OGR thread about the power shutdown.
To summarize, the requirement was to kill power to all 4 track blocks if the breaker trips on any of the 4 AC bricks. So the 4-channel opto-isolator IC chip is configured as shown with the outputs "stacked" in series. A single capacitor smooths out any 120 Hz pulsed DC ripple.
In this case that pesky 3K resistor in each channel of the eBay module is not needed though I'm guessing it would still work. Again, it would probably be expedient to simply add a 10-cent bridge rectifier on each AC input rather than extracting/replacing the DC opto-isolator chips with AC chips.
