I received a catalogue with my order of micro switches today and when looking at the vast selection of power supplies from MPJA Electronics really became confused with some of the terms. Could someone tell me what:
I. A filtered power supply
2.A regulated power supply
3.A linear power supply
4.A switching power supply
Is and how it would relate to a DC layout using LED`s, Tortoises and rail logic signalling devices. As a side comment these MICRO switches look to be real difficult to attach & solder wires to with the terminals so close together. (double & triple pole types)
Thanks for the help
Bob D As long as you surface as many times as you dive you`ll be alive to read these posts.
A filtered power supply has a capacitor on the output to smooth out(filter) the bumps you get from just rectifying AC current. A simple filtered power supply is a transformer, bridge rectifier, and a capacitor. Output voltage raiting is usually an average with an average load - a 12 volt supply will probably read 15 volts or more with no load, and can sag below 10 volts with the rated maximum load.
A regulated power supply has an additional component called a voltage regulator to limit the output voltage to a fixed level regardless of the load (up to the maximum it is rated for). Thus a 12 volt regulated power supply will put out 12 volts at no load, and 12 volts at near maximum load.
A linear power supply is simply any that use a basic power transformer. A linear power supply can be AC, unfiltered DC(just a rectifier), filtered DC, or regulated DC.
A switching power supply uses a more complex circuit to transform voltage without a heavy iron core transformer. They are generally far more efficient than a linear supply and generate less heat. An 8 amp tranformer is a heavy piece of equipment - the switching power supply in your computer typically puts out 10x that or more, and weighs 1/4 as much. Switching power supplies are usually regulated by design.
A tortoise needs DC, it doesn't have to be filtered or regulated, although using unfiltered DC with them tends to make them hum more. LEDs should be filtered and regulated for best results, LEDs are current operated devices and so always need a resistor to limit current. If the power suppyl varies over too wide a range it's tough to get a resistor value that will operate the LED at a safe current value throughout the range. There is one exception, if you want to use LEDs to indicate Tortoise position, you cna wire the LED in series with the Tortoise motor with no resistor required - the Tortoise draws about 15ma stalled and the laws of electric circuits for devices in series says an equal current will flow through them all - so the LED also gets 15ma, perfectly safe. Signalling circuits, especially ones using integrated circuits, want regulated power supplies, although some commercial products will have the regualtor on the signal controller - use the power supply recommended by the manufacturer of such devices in all cases.
As for soldering subminiature switches - there's PLENTY of room. You need to use the correct tool. A 200 watt soldering gun is NOT the device to use to solder small wires and electronic parts. For somethign small liek that you want a small iron with a small tip 25-30 watt. And practice. You CAN melt the plastic parts of a toggle switch, but they aren't nearly as delicate as an LED or other electronic part.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Thanks Randy for the detailed explanation of the above. I made a copy of the post for reference.