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Re: Diode Lighting circuit
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Incidentally, if anyone want to read some info in depth about measuring DCC voltage, I have this document I wrote at my Droipbox site.? I wrote this mainly for the Digitrax groups but it has been passed around a lot. It has everything from test lights (which is usually all you need) to meters that will work and why some won't, oscilloscopes, and so on.? There are many appendices for those who want a deeper dive (there is a lot there).? One appendix shows how a "sensitive ohmmeter" can be used to help find shorts.? At a large HO railroad I work on at a museum, this has been invaluable. The one sort of test light that I do NOT show is an LED with a resistor.? It is advantageous to have more of a load on the DCC voltage than an LED provides.? Some who use an LED light tester also clip a lower resistance across the rails to cause more current to flow.? The reason for this is that there can be a questionable connection somewhere that might be read fine with the low current draw of the LED test light, but not with more current such as when you try to run an engine, and it still doesn't work.? All of the test lights in the document draw significant current to simulate a load. Charles E. "Chuck" Kinzer
On Thursday, December 19, 2024 at 04:14:48 PM PST, Charles Kinzer <ckinzer@...> wrote:
The original post showed a network that is clearly one of the diode networks used for "constant lighting" when using incandescent bulbs.? Furthermore, it affords reversible constant lighting - of incandescent bulbs.? All of my comments are in that context. If you want answers about LED's, ask a question about LED's But the diode circuit shown WILL destruct if put directly across the rail power unless not much current is available from the power source.? It is a question of how much power each diode has to dissipate as heat. In the diode circuit shown, the addition of the motor in series does act as ballast.? Just like a resistor in series does the same for an LED. Charles E. "Chuck" Kinzer
On Thursday, December 19, 2024 at 04:01:44 PM PST, Mike Swederska via groups.io <mikesscale@...> wrote:
Wow! If you guys read my email and you¡¯re telling me that they¡¯re gonna blow up if you go across the rails.I can¡¯t believe it. With a 1000-3000 ohm resistor on the lead of the LED directly to the rail is no different than going across DCC rails at 14 V. And as far as constant lighting is concerned, the LED will come on in less than one volt on the rails when you turn on the throttle giving you constant lighting before the locomotive even begins to move on DC. The resistor is what regulates how much DC electric getsto the LED once the throttle is turned up past one volt. The LED itself is what creates the directional lighting. He is not using light bulbs and the circuit that you guys are showing as old school for lightbulbs. He¡¯s using LEDs. Why do you need the motor to be a ballast? I don¡¯t understand. If I¡¯m correct, am Ithinking, even with the DCC decoder, the function wires white, and the blue do not have anything to do with the motor. Whatever voltage is on the rails going to the decoder goes right through the decoder and to the LED. That is why you use resistors whether you use a lightbulb or LED in DCC. Mike Swederska? On Dec 19, 2024, at 4:55?PM, JGG KahnSr via groups.io <jacekahn@...> wrote:
I figured it was a constant lighting circuit, perhaps directional, too, and that the bulbs mounted in the shell are probably low-voltage which would blow if they got any significant part of 12v.
Jace Kahn
From: [email protected] <[email protected]> on behalf of Ed Loizeaux <Loizeaux@...>
Sent: Thursday, December 19, 2024 4:46 PM To: [email protected] <[email protected]> Subject: Re: [S-Scale] Diode Lighting circuit ?
On Thu, Dec 19, 2024 at 11:43 AM, Mike Swederska wrote:
don¡¯t hook it to your motor in my opinion that¡¯s incorrect because it does affect the Motors RPM ?output. I am taking an uneducated guess here, but it looks to me like the circuit enables the lights to illuminate
BEFORE the motor starts to rotate.? Thus, the lights could be on while the train is waiting at the station.? Or something like that.? Just a guesstimate, but what the heck..........it might be correct.? Ed L.
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Ed Loizeaux
Los Altos, CA -- Mike Swederska Meramec Valley Lines Modeling Mopac equipment in 3/16 Don't let perfection get in the way of good enough! Keep model railroading fun! |
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