Here is a short list of electronics vendors that sell items of interest for hobbyists. If nothing else, the sites are fun to browse. Note that I am not financially affiliated with any of these vendors.
Thursday, July 23, 2009
Monday, April 20, 2009
Cheap alternative to Silflor
I just love learning about cheap and creative approaches to scenery. I recently heard about craft store pot toppers as a much-cheaper-than-Silflor material for vegetation. Neat!
LED "rosettes" to light structures
I wrote earlier about using yellow LEDs to light structures internally. Having just started construction on a new module, I've decided to apply this technique, and have sorted out some better specifications than the ones I previously posted.
The advantage of LEDs is that they are dim enough that, with proper positioning, they won't make the structure walls "glow" in the dark, even if you don't paint the insides of the structures black (a chore I despise, and one which presents many opportunities for accidentally painting over places that need to be glued). Their dimness also means you pretty much need one LED per window, sometimes two for a big window.
So, because even a simple structure usually requires several LEDs, I've been constructing circuits of 6 LEDs. I bend the leads of 6 LEDs, solder them positive-to-negative in series, then solder a 220-ohm resistor to the positive end (a value that will give the right current to the LEDs using most transformer accessory power), and two wires to the opposite ends, making a kind of circle I call a "rosette." This rosette/array of LEDs can then be arranged inside the structure, so the LEDs are a millimeter or two behind each window, pointing right at it ... of course it's a good idea to diffuse the light by backing the window with vellum, frosted mylar, paper, etc.
Each of these circuits will consume 20-25ma, depending on transformer voltage. I use a single full-wave bridge rectifier to feed the circuits (since the LEDs only conduct in one direction). As you can surmise, you can power a large number of LEDs using only a fraction of the power from one transformer.
The advantage of LEDs is that they are dim enough that, with proper positioning, they won't make the structure walls "glow" in the dark, even if you don't paint the insides of the structures black (a chore I despise, and one which presents many opportunities for accidentally painting over places that need to be glued). Their dimness also means you pretty much need one LED per window, sometimes two for a big window.
So, because even a simple structure usually requires several LEDs, I've been constructing circuits of 6 LEDs. I bend the leads of 6 LEDs, solder them positive-to-negative in series, then solder a 220-ohm resistor to the positive end (a value that will give the right current to the LEDs using most transformer accessory power), and two wires to the opposite ends, making a kind of circle I call a "rosette." This rosette/array of LEDs can then be arranged inside the structure, so the LEDs are a millimeter or two behind each window, pointing right at it ... of course it's a good idea to diffuse the light by backing the window with vellum, frosted mylar, paper, etc.
Each of these circuits will consume 20-25ma, depending on transformer voltage. I use a single full-wave bridge rectifier to feed the circuits (since the LEDs only conduct in one direction). As you can surmise, you can power a large number of LEDs using only a fraction of the power from one transformer.
Tuesday, September 16, 2008
Sharing 16-20V AC accessory power between turnouts and lights
It's often said that incandescent lights on a layout, be they inside your structures or the streetlamp variety, look better and last longer if they are run below their rated voltage, for example running a 12V lamp at 9V. To do that, though, you can't just wire up all the lamps to your accessory power, you generally have to run them off the variable DC output of an extra transformer.
I have a nifty solution for this problem, which also reduces flicker in the lights if you use the same accessory power with remote turnouts. Using diodes, create two circuits off the accessory power with each circuit rectified in a different direction. The half-wave rectified power in one circuit is still plenty powerful for the coils in your turnouts. The other circuit goes to the lights, and since there is a lag when incandescent lights switch on or off, they appear to still be glowing continuously, albeit a bit dimmer.
Note that this doesn't work for any LED lights, the half-wave power will product a very noticeable flicker since LEDs shut on and off instantaneously.
I have a nifty solution for this problem, which also reduces flicker in the lights if you use the same accessory power with remote turnouts. Using diodes, create two circuits off the accessory power with each circuit rectified in a different direction. The half-wave rectified power in one circuit is still plenty powerful for the coils in your turnouts. The other circuit goes to the lights, and since there is a lag when incandescent lights switch on or off, they appear to still be glowing continuously, albeit a bit dimmer.
Note that this doesn't work for any LED lights, the half-wave power will product a very noticeable flicker since LEDs shut on and off instantaneously.
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