Dean’s been in touch again with another electronics ‘how to’. If you missed his last one, it’s here.
“In a previous post, I described by system for lighting buildings and hinted about my capacitive power supply, for snap switch control. I’m using Atlas switches with their push-button controllers.
Looking back, I wish I had started out with the Tortoise switch machines, since they are more robust and electrical controls are simpler. But at this point, I don’t want to deal with the hassle and work of converting all my switches.
A wiring diagram of my capacitive switch power supply is shown below.
The power block on the left supplies 22 vDC from the house line. It’s from an old laptop I don’t use anymore.
The current flow in limited by four 270 ohm, 1-Watt, resistors wired in parallel to give the equivalent of a 68 ohm, 4-Watt, resistor.
These provide current into the two capacitors store the power to throw the switches. (Note that these are electrolytic capacitors that must be wired correctly as of polarity. If you reverse the connections, they might blow up, and would be totally destroyed.)
All these components can be obtained from suppliers (I got mine from Radio Shack which is pretty much gone).
The LED provides a power indicator. In operation the capacitors build up voltage to 22 v over a short couple of seconds. When you push a button, the stored power quickly goes to the switch mechanism and the LED goes out.
When you release the button, the voltage again builds up and the LED lights. Switch controls are connected to the red and green bus leads, one for each switch. The red, black, and green leads go to a switch, wired as shown in the Atlas package the switches come in.
Everything inside the red box in the diagram above is shown below. The electronic parts are soldered onto a printed circuit board with many unconnected holes (from EBAY). Wires are routed and soldered between the components as needed.
The circuit board is held to the front plate with screws and spacers. Everything else is held together on a wooden board with hot glue which is then hot glued to the plate.
The front and back of the circuit board is shown below. Wiring is not critical, just make sure everything is connected correctly. The resistor for the LED is inside the blue shrink tubing.
Below are the two control panels for the yard at Cassiusville (panel on the right) and the Inverashur passing siding (panel on the left, Inverashur siding behind the town).
Another switch on the right of the Cassiusville passing siding is out of the picture. Readers of my last blog will recognize the station and mine.
The back of the yard panel is shown below. They don’t make 3-gang cover plates, so I have to cut a 1-gang and a 2-gang and glue then together with epoxy.
I hope I have made everything clear. Write in your questions.
A huge thanks to Dean – please do post you comments and questions below.
And don’t forget today is the last day to save $18 with the launch price of the latest print out scenery. Here’s what it looks like:
That’s all this time folks.
Please do keep ’em coming.
And if you want to jump in and start your layout the Beginner’s Guide is here.