O22 switch and 151 semaphore

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  • Member since
    March 2013
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Posted by BigAl 956 on Thursday, April 20, 2023 9:22 AM

You would do better using a block signal. The 151 will burn out after a few hours. I tried this with the MTH reproduction signals and burned out their coils in an hour.

  • Member since
    November 2007
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Posted by stuartmit on Tuesday, April 11, 2023 3:28 PM

never Understood the workings of the 151 across the center band outside binding posts of 022, and I would like to.  


Below is info from Bob Nelson in December 2016. But First off, I confused hook up of 151 to 022. It does not connect acroos all 3 terminals of the 022. 

one terminal does connect to an outer terminal on 022, and others to track power and outer rail.


from Bob Nelson:

The 022 turnout does not ground the control terminals (that is, connect them to the common outside rails).  These terminals are connected to the center rail (or the optional fixed voltage) through the solenoids that operate the turnout.  The controller grounds one of the terminals and, as the turnout is thrown, a switch in the turnout open-circuits the switch motor solenoid.

The usual way of operating a signal from an 022 exploits the fact that a small lamp (in the signal) connected to a control terminal and returned to ground, does not draw enough current to throw the turnout.  This same method is used in the controller to operate its indicator lights.  I suspect that a semaphore solenoid (returned to ground rather than the center rail or fixed voltage) would draw so much current that this scheme would not be practical.  But it wouldn't hurt to try it.


My comment to add to Bob's last is that i can tell you that a relay hooked with its two coil terminals hooked between center and one exterior post of 022 will energize in one position of the switch or the other, and the wire to the outer post can be connected to energize the relay when switch is in one or the other position or the other. In this way its contacts can turn power on and off to either branch of the switch or turn on or off some other function. But of course you can wire the 151 directly to the switch, or or the gateman or block signal, as well, and so don't need the relay. Further, as was pointed out, neither the relays or Lionel's solenoid operated accessories will tolerate extend periods of being energized; they will overheat.


  • Member since
    November 2007
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Posted by stuartmit on Tuesday, April 11, 2023 3:10 PM

Suppose you have a 151 solenoid controlled semaphore hooked up across the center post and an outside post of an O 22 switch. The semaphore will be activated in one position of the switch, but not in the other. If you wanted to solenoid to pull the semaphore blade down when the switch is set in a position where that would not normally happen, can you connect the side of the 151 which does not go to the center post through a momentary push button and then do your accessory line so that by pushing the push button the solenoid is activated and the blade is pulled down? 

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  • From: Hopewell, NY
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Posted by ADCX Rob on Sunday, April 9, 2023 8:33 AM

The 151 was not designed for continuous duty and the meltdown period would depend on the operating voltage.

A properly spec'd relay would be chosen for a continuous duty cycle and could remain energized indefinitley.


  • Member since
    November 2007
  • 447 posts
O22 switch and 151 semaphore
Posted by stuartmit on Sunday, April 9, 2023 7:17 AM

If you connect the semaphore across the terminals of 022 switch the semaphore can be activated to indicate the "engineer" should stop the train with switch set in one or other position.  For how long can the solenoid tolerate being energized at 14-16 volts? 

same question would apply to a relay hooked up In similar fashion to control current flow to a block of track.

but how long before things start smoking? 

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