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Hi All,

I have built some nifty occupancy detectors with IR sensors that basically fit under a piece of fastrack - it’s a relatively simple pcb, has two IR sensors, and sensitivity pot, and a esp8266 chip that sends occupancy data over wifi via MQTT.  (I have a software dev/industrial IoT background). Currently this is all powered by a separate 3v dc buss.  My question is since I have 18v ac right at the fastrack - is there a good safe and *compact* way I could just take power from the track and have everything inside a piece of fastrack?  I know there are thing like the Lionel crossing gates that have lower voltage components - but they are not constantly on.  I worry most about heat and of course building a board that is small enough to fit under the track.   It’s not a huge deal to have a separate power source, but it would be good to have all this capability I built available in adhoc setups too and not having to run separate power.  Compact and dealing with any heat seem to be my challenges.

thoughts?  

thanks


-chris

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It should be pretty easy to power from the 18V Fastrack, it obviously depends on the current required.  Given that the esp8266 is pretty low power, I'd assume a simple linear regulator setup would do the job here.  What voltage and what current are you looking for?

What overall footprint are you allowing for?

Last edited by gunrunnerjohn

What about conventional operation?  You imply that the esp8266 will work at 3 volts for its Vcc.  Can the rest of the circuit operate at 3V?  Are you sending MQTT over TCP/IP (as is typical)?  Wired or wireless? 

With a low dropout regulator you might be able to get all of this to work at 5 VAC on the track.

Mike

Last edited by Mellow Hudson Mike

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