Can any of you electronic people tell me if I could use a 12vdc SWITCHING power supply to power leds and tortoise machines or do I need a filtered power supply. Also do any of you use the 3mm leds in your control boards? I ask about the power supplies because there seems to be a lot more of them on the electronic store sites than the plain filtered ones.
Bob D As long as you surface as many times as you dive you`ll be alive to read these posts.
Circuitron actually sells a flitered transformer for their machines and electronic circuits.
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A switching power supply will work just fine for Tortoises and LEDs. You might want to use only 9 volts with the Tortoise as they're be a bit quieter, but a switching pwoer supply is perfectly safe for electronics - it's the kind of power supply in your computer.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Switching supplies are OK as long as they have some load. A few panel LEDs should be OK. At no load the output may read "0" volts.
I use 250 Watt computer power supplies to run Tortoise switch motors, block signals, grade crossings, building lights, and everything except the trains on both a large HO scale club layout and my HO scale home layout. A larger supply has outputs of 12, 5, and sometimes other voltages.
Bob,
An old comupter power supply will give you at least 5 & 12 volt DC outputs. You are still going to need dropping resistors with those LED's. Usually they will not handle more that 3 volts. I have a couple of old 12VDC 'Wall Warts' that I use to power my Tortoise machines. One has a 850 ma rating - should power over 50 Tortoise machines! There are a lot of old cell phone chargers in the 3.3VDC range as well.
Jim Bernier
Modeling BNSF and Milwaukee Road in SW Wisconsin
Oh yeah - to avoid using ANY of the Tortoise contacts for panel indicators, AND so you don't have to use resistors, consider putting the LEDs in series with the Tortoise motor leads. Connect two back to back, red/green, red/yellow, green/yellow, whatever colors you prefer. Back to back means the anode of one to the cathode of the other, and the cathode of the first to the anode of the second. Usually indcated by one wire being longer than the other - conenct a long to a short,, conenct the two free leads. Now, in oen of the wires runnign to the Tortoise motor terminals (1 and 8), cut it and connect one pair of LED leads to the toggle side, and the other pair to the Tortoise side. Depending on which way the Torotise is set, one or the other LEDs will light. If it's the wrong one - just flip the pair over. While the Tortoise is moving, both LEDs will glow dimly, then the one for whichever direction you lined the switch will light brightly once the Tortoise finishes moving. Since the Tortoise only draws about 10-15ma, the current to the LEDs in series will also be limited to 10-15ma, which is perfectly safe for the LED. You'll get a voltage drop - most red/green/yellow LEDs are about 2.1 volts, so from a 12 volt power suppyl the Tortoise will see about 10 volts - plenty - it will run somewhat slower but also a whole lot quieter on less than the full specified voltage.