Here is a board I made to check led intensity, just touch one end of led the resistor and the other to the copper wire in the middle, at top diagramed to led sides and of course to the dcc blue wire.
Is also great for to find quickley those loose resistors laying around the bottom of the tray, just hold it to the board and find a match to see its value.
Any how to me its a time saver, quick and easy to use.
Nice. I assume you use a 12 vdc power supply?
In conjucntion with a multimeter on 20 ma DC scale you can get an idea of current with different value resistors.
I did that a few years ago and recorded the current readings.
Super bright LED's require a lot more resistance I eventually found out.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
I can attach two quick test leads to this board in various ways., go to the track, directly to the DCC board function (using the voltage from the board) or to any voltage battery to test led intensity or any setting with a dc transformer. Checking the led buy just touching the verious resistors on the board from one to another untill I find the brightness I want..
Yes, forgot about directly to the DCC track. Good idea. My NCE power cab puts 13.6 VAC to the track. The 3mm red LED in the Cab panel has a 1k resistor between it and the DCC power. Has not burned out yet.
FOr figureing out any resistor, if you don;t have the color code memorized, there are these:
http://www.amazon.com/Elenco-cc100-1-Color-Code-Calculator/dp/B0002SUQ8G/ref=sr_1_1?ie=UTF8&qid=1456346816&sr=8-1&keywords=resistor+color+wheel
I have a Radio Shack one that ir probably 30+ years old now.
I also have the electronic version as an app in my phone and iPad, just scroll the wheels to match the colors on the resistor in question and the value is displayed. DOn't use it much as I happen to have the color code memorized - the tolerance colors are the ones that I need to occasional look up.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
richg1998 Yes, forgot about directly to the DCC track. Good idea. My NCE power cab puts 13.6 VAC to the track. The 3mm red LED in the Cab panel has a 1k resistor between it and the DCC power. Has not burned out yet. Rich
ANd it shouldn't, 1K results in less than 10ma in the LED which cna handle at least 20ma, and probably closer to 30ma (red LEDs are more robust than white ones). Using track voltage to feed the substitution box should be worst case - the actual voltage available to the LED in a decoder running on that same track is about 2 diode drops less as it goes through the bridge rectifier on the decoder.
For a fancy version, it could all be in a small project box with clip terminals and a rotary switch selecting the resistor values. Better than a general purpose substitution box, which can usually select from 1 ohm to 10 Mohm - the low end being guaranteed to fry an LED if using 12-14 volts, the upper end too high to allow the LED to light. A special one designed for model railroad use would have the highest and lowest values still within workable values so the lowest wouldn;t harm the LED and the highest would still work.
Thanks Randy, as with anything theres numorous way to do things LOL I just like tinkering with stuff and figuring out things.
Always enjoy reading your reply's on post on this site. Havent been on this site for years, as there was too much drama at the time I left.
John
It's just my AR side getting in the way - I don;t think I could live with a bare board with resistors in it as my test jig, I'd have to rig it up with the rotary switch and put it in a nice box. I made a decoder tester once, and also a beep box that doubled as a track voltage detector (toggle switch - buzzer, bicolor LED and a 1K resistor with some alligator leads coming out the side. Flip one way, alligator clips connected to battery and buzzer for continuity check - or to clip on the main track bus so it would beep if you crossed a pair of feeders, flip toggle the other way, teh leads wnt throught eh 1K resistor to the LED. Bicolor so I could see if address 00 was on and non-zero speed (doesn;t apply unless you have Digitrax or Lenz) and also you could put it across rail gaps and see if the boosters were out of phase). I could have just soldered some clip leads to a buzzer and been done, but I just had to get a small project box and mount the components inside, and put labels on the toggle switch. Even my etst track, when I added the Locoprogrammer and a toggle to switch between it and my PR3 - all you have to do it point the toggle at the device you want to use (the gotcha is the connections on the bottom are the opposite way!), but I put labels on it. I have one light in the house that has control from 3 places - the other night I walked the extra distance to the one that had the handle in the up position to turn off the light (so all 3 swtches are down for off). My GF thought this was pretty funny. But darn it, if a toggle handle moves vertically, up is on and down is off. Or like when I was makign resistor wheelsets. After the first 3 or 4 I got tired of testign them by trying to hold the test probes to the wheels to test them, so I took a piece of track, soldered some wires to it, and attached banana plugs to the other end to plug into my meter's test terminals. Overkill, but it's neat. I did stop myself from building a test rig circuit with a green LED for good and red for no good. But that may happen soon. For my new bench I figure I will have 3 or 4 thigns to potentially connect to the test track - a DC power pack, a PR3, the Lokprogrammer, and maybe my original Zephyr. Now, I could just plug and unplug things, or maybe put it through a rotary switch to select one of 4 inputs. Bt nope, I have a circuit designed and a program already working for an Arduino controlled switch, with an LCD menu and 3 pushbuttons to navigate the menu and select an option. And LEDs to indicate which input is selected as well.