The article in the November CTT, “Overcoming a common semaphore mistake” (pg 89), got me thinking about a postwar semaphore wiring problem I’ve got. I have several hidden switches, and I want to hook up semaphores to give a visible indication of the position at which the switch is set. Can this be done without using a relay? I thought the following would work: (looking from the back of the semaphore) hook the center terminal to a constant 15v, and the left terminal to ground, and the right terminal to either the left or right terminal of the switch. But when I do this, the semaphore only goes down while I hold the switch lever to one side, and both switch lights on the controller come on. When I release the switch lever, the semaphore goes back into the neutral (up) position. Any ideas on how I can make this work? Bob A. P.S. I’m delighted to have gotten my CTT on the first day that someone else posted that they’d gotten theirs! Usually in So. Calif., I’m many days late!
I think you mean that both controller lights come on after you release the lever. That is what I would expect.
You can do what you want by replacing the controller switch by a simple single-pole-double-throw switch. (This would not work with O27 switches.) One obvious drawback is that the lamps are in the old controller, with the disused momentary switch. You would have to build your own controllers or heavily modify the old ones to get lamps and switch together in the same unit, or mount the new switch and separate lamps on a control panel, if that bothers you. Another problem to worry about is whether you will damage the semaphore by leaving it energized indefinitely. At the least, I would operate it on the very lowest voltage that it will respond to.
Bob - Thanks for your, as always, useful and knowledgeable reply. I think I’ll forego this idea and explore other options. Bob A.
One thing you can do is connect a 153 block signal to 022 switches.
Yes, the block signals will do wonderfully. Thanks for reminding me that signal lights work well off switch terminals. Bob A.
It is possible to wire into the 022 switch at the solenoid but to wire in a semaphore might be a mistake because the relay or electromagnet can over heat and burn out quickly.
Try using a block signal light with two lights as this can be tied in better to an 022 switch, the center wire at the switch housing is the common and the other two wires control the light and direction. Adding an extra light won’t hurt. 027 switches are differant and this will not work with them.
Lee F.
No separate “hot” wire to the block signal. Connect all three of its terminals to the three terminals of the switch.