I’ve installed a few lionel semaphore signals on my layout. there set at low voltage so the up & down motion is very realistic.T hat’s the good news. the bad news is they make a loud buzzy noise. Any ideas how to do away with that???
Run them on dc?
o.k Bob. But how do you do it??? EASTER
What if you upped the voltage a bit - I have just one - and it slams up and down when activated (in my limited experience watching them on the former C&NW, that’s pretty realistic) but it is silent.
Isn’t there something out there that would changs a/c into dc current??? Easter
A rectifier. For any substantial current, such as your semaphore probably draws, you need a full-wave rectifier, so as not to saturate the transformer. There are two simple kinds:
You can use a center-tapped transformer. The center tap is one output terminal. The ends of the secondary winding are connected to the anodes or cathodes (the same for both) of two rectifier diodes. The other ends of the diodes are connected together and are the other output terminal. You probably don’t want to do this, since there is no practical way to adjust the transformer.
You can use a bridge rectifier. These can be bought as a 4-terminal unit. The ac input goes to two of the terminals, often marked with the ~ symbol, and the other two terminals, often marked + and -, are the output. If you are using a control rail to operate the semaphore, you must use a separate transformer (which may be adjustable) for this dc supply, since the output of the rectifier, not the input, must have a common terminal with the transformer that powers the train.
The raw full-wave dc output may still make some noise at the semaphore, in which case you will need to filter it, by sticking an electrolytic capacitor across it. The capacitance depends on the load and how smooth the voltage has to be to keep the semaphore quiet.
Or you could just buy a small dc supply intended for HO or N trains.
Bob,thanks for sharing your knowledge. I like your last paragraph. I’ll go with an HO power pack. Easter