How many amps does a twin coil turnout machine take?
Will a 0.5 amp momentary pushbutton switch be O.K.?
I could’t find any specs. on the internet.
Jerry
The current draw is going to depend upon the brand and year of manufacture. An Atlas Snap Switch twin-coil is not going to require as much juice as a Peco or one of the old Kemtron switch motors, which must overcome the resistance of their springs. You’d probably be much better off with a double-throw, center off, momentary toggle switch rated at 1 Amp.
A capacitive discharge circuit is a big upgrade for your twin-coil switch machines. I built one for a few dollars in parts from Radio Shack, based on a circuit I got by Googling. If you’re using Peco machines, you really need one of these.
Entering the phrases “twin coil switch machine” + “current” into Google yields a number of interesting pages with helpful results. This info came from write-ups by Tony’s Train Exchange and Loy’s Toys write-up found with this search:
PECO switch machines .8 Amps to 2 Amps depending on model
NJ Industries 4.6 Amps
So it appears there is some variability depednign on manufacturer and model. Aren’t there instuctions with your switch machine?
Radio Shack mini-buttons have a rather limited life when used with 1960-era twin coil machines. After having to replace several, I went to a very different momentary-contact switch arrangement (shorting rotary switch) that has the advantage of indicating turnout point position on the panel. Much more expensive, unfortunately.
I have also used the hot probe system - screwheads in the track diagram lines connected to the coils, actuated by a stereo plug powered from the turnout power supply. The screwheads and plug got fried rather quickly, but could be cleaned up with fine-grit sandpaper. Coating them with solder might make the arc pits self-healing.
Chuck
The coil uses a short burst of high power. It will only draw as much as it needs, so your supply amperage can’t be too large. If you throw more than one switch at a time and/or have a long run of wire, the requirement increases. I use 3 amp, 20 vdc power supply and a home brew Capacitor Discharge Unit with a minimum of 18 gauge stranded wire.
The CDU should limit current to prevent coil burnout. The rating of the switch is basically how much currnent it can handle, not how much it will pass. If in doubt, buy a good pre-built CDU like the Circuitron Snapper or the Miniatronics PDC-1 (which I use) and some SPDT center-off momentary switches like the ones made buy Miniatronics. These will handle up to 5 amps. This setup may be a little expensive compared with building your own CDU and finding some cheaper switches, but is reliable.
Thanks for the help.I have many new Kemtrom twin coil machines with the contacts without instructions. These are at least 25 years old. Do I need a CDU for each switch?
I have been out of the hobby for 25 - 30 years and am playing catchup.
One CDU will handle all your turnouts.
Oh, and welcome back. Glad to have you around.