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Model Forum / General / Railroads / May 2008Best Decoder for Athearn F3
What decoder will work without blowing the headlights on the Athearn Gensis F3 skeet06 <atlow8@hotmail.com> wrote in news:326a3176-d284-4016-b78b- 55368e53e3ef@b64g2000hsa.googlegroups.com: > What decoder will work without blowing the headlights on the Athearn > Gensis F3 All of them; None of them. The decoder's function output wants to put out around 12V for the headlight, so if your headlight is rated for less voltage than that they'll fail. What voltage and current are your headlights expecting? If it's not 12- 16V, you'll probably need a dropping resistor of some value. Determining the value is easy, use Ohm's Law. V = C*R (Just remember VCR. Standard Ohm's law format uses I in place of C.) Voltage = Current * Resistance Resistance = Voltage / Current The current should be listed on the packaging, if not you'll have to measure it yourself with an ammeter. It's not to hard usually. It'll be the value in "Amps" or "Milliamps" The May 2008 Model Railroader has an article that explains this. One more thing: Does your locomotive have an 8-pin DCC socket? It's probably best to get a decoder to fit that rather than hardwiring it yourself. Puckdropper  SignatureYou can only do so much with caulk, cardboard, and duct tape. To email me directly, send a message to puckdropper (at) fastmail.fm > All of them; None of them. The decoder's function output wants to put > out around 12V for the headlight, so if your headlight is rated for less > voltage than that they'll fail. No, you can dim the output on many decoders. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe >> All of them; None of them. The decoder's function output wants to put >> out around 12V for the headlight, so if your headlight is rated for less [quoted text clipped - 3 lines] > > Klaus Dimming isn't what's needed here. Most decoders have a function output of around 12v and Athearn Genesis has 1.5v bulbs. With this situation you need to use drop resistors using ohms law as was described. There are some decoders that do have a function output of 1.5v -- TCS A6X is one. There may be other manufacturer's decoders with this feature but you would have to check the specs to find them. Personally for the Genesis F units I use a TCS T1 and a 910 or 1000 ohm drop resistor for each bulb -- I also dump the Genesis circuit board, which takes up a lot of room, and make my own small connection board on top of the motor. Jim On 5/11/2008 1:50 PM Jim Bright spake thus: >>> All of them; None of them. The decoder's function output wants to put >>> out around 12V for the headlight, so if your headlight is rated for less [quoted text clipped - 5 lines] > around 12v and Athearn Genesis has 1.5v bulbs. With this situation you need > to use drop resistors using ohms law as was described. In this case, wouldn't it be a better idea to replace the lamps with 12-volt ones? You can "drop" the voltage with a resistor as you describe, but you're going to end up dissipating a lot of power as heat, depending on how much current the bulb draws. Could end up cooking something. SignatureThe best argument against democracy is a five-minute conversation with the average voter. - Attributed to Winston Churchill > On 5/11/2008 1:50 PM Jim Bright spake thus: > [quoted text clipped - 16 lines] > depending on how much current the bulb draws. Could end up cooking > something. 12V bulbs get pretty hot compared to 1.5V bulbs. An alternative would be to replace the 1.5V bulbs with LEDs. Signaturewolf k. On 5/11/2008 2:48 PM Wolf Kirchmeir spake thus: >> On 5/11/2008 1:50 PM Jim Bright spake thus: >> [quoted text clipped - 20 lines] > > An alternative would be to replace the 1.5V bulbs with LEDs. So, on that subject: anyone know if non-blue "white" LEDs are available yet? A lot of people don't like those psuedo-white ones; not very realistic-looking. SignatureThe best argument against democracy is a five-minute conversation with the average voter. - Attributed to Winston Churchill > On 5/11/2008 2:48 PM Wolf Kirchmeir spake thus: > [quoted text clipped - 27 lines] > yet? A lot of people don't like those psuedo-white ones; not very > realistic-looking. Go over them a couple of times with a yellow high-lighter. Definately improves the look. Len For " White " LED go to Train Control Systems they have some very nice LED that burn pure white, start out at 650 ohms and try up or down until you get your desired light out put. I am useing them in steam engine head lights [ brass ] and they are great. Malcolm. > > On 5/11/2008 2:48 PM Wolf Kirchmeir spake thus: > > [quoted text clipped - 40 lines] > > Len > For " White " LED go to Train Control Systems they have some very nice > LED that burn pure white, start out at 650 ohms and try up or down until > you get your desired light out put. I am useing them in steam engine head > lights [ brass ] and they are great. Of course, only when you run your train at night because until almost the end of steam, steam locos ran with the headlights "off", something most modellers these days don't realise. -- Cheers Roger T. Home of the Great Eastern Railway at:- http://www.highspeedplus.com/~rogertra/ Latitude: 48° 25' North Longitude: 123° 21' West > So, on that subject: anyone know if non-blue "white" LEDs are available > yet? A lot of people don't like those psuedo-white ones; not very > realistic-looking. There is Yoldal sunny white or warm white, in Europe many of us buy them at http://www.dotlight.de/shop/ <http://www.dotlight.de/shop/product_info.php/cPath/167_172/products_id/410> Another dane has replaced all lightbulbs and LEDs in his trains with the Yoldal LEDs, it looks great! Look at: <http://modeltogfoto.spaces.live.com/photos/cns!400299DD87F2B091!553/cns!400299DD 87F2B091!565/?ViewType=4> Or this one and forward: <http://modeltogfoto.spaces.live.com/photos/cns!400299DD87F2B091!255/?ViewType=4& searchtype=5&index=15&handle=cns!400299DD87F2B091!270> Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe > 12V bulbs get pretty hot compared to 1.5V bulbs. A 1,5 volt 0,1 watt and a 12 volt 0,1 watt have pretty much the same temperture..... > An alternative would be to replace the 1.5V bulbs with LEDs. And then you have the resistor problem again. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe On May 12, 2:47 pm, "Klaus D. Mikkelsen" <er.du.saa.k...@du.kan.gaette.den> wrote: ... > And then you have the resistor problem again. > > Klaus Why are resistors such a problem? I work in N scale and I have no problem installing resistors in the LED circuits in locomotives. Lately I've been using SMD 1206 or 805 size resistors. They are very tiny. I've also noticed that certain decoders already have empty pads on the circuit board designed to accept resistors in series with a function output. I think I've seen that on some N scale Digitrax decoders. Peteski On 5/12/2008 10:08 PM Peter W. spake thus: > On May 12, 2:47 pm, "Klaus D. Mikkelsen" > <er.du.saa.k...@du.kan.gaette.den> wrote: [quoted text clipped - 8 lines] > function output. I think I've seen that on some N scale Digitrax > decoders. Guess it isn't that big a problem after all; doing a little back-of-the-envelope calculation shows that to divide* 12 volts down to 2 for a LED requires an 1/8 watt resistor, so it looks like even a surface-mount one would be good enough. * To be technical about (and lord knows we like to be technical round heah', don't we?), one doesn't "drop" voltage; one divides it. In this case, with a resistor in series with the LED, the divider puts 10 volts across the resistor and 2 across the LED. SignatureThe best argument against democracy is a five-minute conversation with the average voter. - Attributed to Winston Churchill > On 5/12/2008 10:08 PM Peter W. spake thus: > [quoted text clipped - 20 lines] > case, with a resistor in series with the LED, the divider puts 10 volts > across the resistor and 2 across the LED. As always, you are correct! No need to propagate even the slightest misinformation on a toy choo-choo forum. :-) Peteski > In this case, wouldn't it be a better idea to replace the lamps with > 12-volt ones? You can "drop" the voltage with a resistor as you > describe, but you're going to end up dissipating a lot of power as > heat, depending on how much current the bulb draws. Could end up > cooking something. You might get around the heat issue by using a 780x series voltage regulator. (The 78L0x series is low current and small package size.) There's also the LM317LZ adjustable regulator (that can work as both a voltage or current regulator.) MR had an article in April 2000 about LED headlights that used this. (The same basic circuit is in the LM317LZ's datasheet.) The nice thing about resistors is they're able to be placed inline with the wire, so they don't take up much extra space. If heat dissipation is an issue, one can use series resistors to spread the heat out across several smaller resistors. Puckdropper SignatureYou can only do so much with caulk, cardboard, and duct tape. To email me directly, send a message to puckdropper (at) fastmail.fm On 5/11/2008 9:46 PM Puckdropper spake thus: >> In this case, wouldn't it be a better idea to replace the lamps with >> 12-volt ones? You can "drop" the voltage with a resistor as you [quoted text clipped - 4 lines] > You might get around the heat issue by using a 780x series voltage > regulator. (The 78L0x series is low current and small package size.) You could, but keep in mind that even a voltage regulator will dissipate some heat; it's just a linear device, and that extra voltage (12 - 1.5 v) has to go somewhere. Bigger voltage drop = more heat. SignatureThe best argument against democracy is a five-minute conversation with the average voter. - Attributed to Winston Churchill > In this case, wouldn't it be a better idea to replace the lamps with > 12-volt ones? No 19-volts ones.... Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe > There are some > decoders that do have a function output of 1.5v -- TCS A6X is one. Jim hit the nail on the head when he mentioned the A6X. The A6X actually has an active regulator circuit, not just resistors, so it plays very nicely with even those notorious 1.5v Genesis bulbs. I've put them in all my Genesis locos, and have never had any of the original 1.5v bulbs fail. Stevert > Dimming isn't what's needed here. Yes it is. > Most decoders have a function output of around 12v and Athearn > Genesis has 1.5v bulbs. Yes and then you dim the brightness so the average output is 1,5 volts. But it is better to use voltage drop by a 1kOhm resistor and then dim to get sufficent light level. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe On May 12, 2:45 pm, "Klaus D. Mikkelsen" <er.du.saa.k...@du.kan.gaette.den> wrote: > > Dimming isn't what's needed here. > [quoted text clipped - 4 lines] > > Yes and then you dim the brightness so the average output is 1,5 volts. <snip> > Klaus This idea works fine in theory but I wouldn't trust it. Dimming on standard decoders is done by controlling a width of a pulsating DC which in oths "on" state is close in value to the track voltage (minus 1.4V). That is about 12 volts. This pulse is not guaranteed to always stay pulsing at an average voltage of 1.5V. For example when the decoder is being programmed it'll apply the full voltage to the function outputs during the programming packet acknowledgment. Or when the decoder "blows its brains" (which does happen), it will reset the outputs to full brightness. In either case the 1.5V bulb will be blown instantly. You'll end up changing those 1.5V bulbs way too often. More reliable solutions are to use voltage dropping resistor or changig the lights to either 12V bulbs or LEDs with a current limiting resistors. Peteski > This idea works fine in theory but I wouldn't trust it. And thats why i wrote: "But it is better to use voltage drop by a 1kOhm resistor and then dim to get sufficent light level." > For example when the decoder is being programmed it'll apply the full > voltage to the function outputs during the programming packet > acknowledgment. Not aon alle decoders. > Or when the decoder "blows its brains" (which does happen) I am still to se one - I'm allmost allways using the ESU decoders. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe On May 13, 1:29 am, "Klaus D. Mikkelsen" <er.du.saa.k...@du.kan.gaette.den> wrote: > > This idea works fine in theory but I wouldn't trust it. > [quoted text clipped - 15 lines] > Klaus > -- To each its own... I work with computers so I don't trust any consumer-grade electronics. Especially ones driven by microcontrollers with possibly buggy firmware. And ones greatly affected by voltage spikes and other assorted DCC wiring ailments. You make it sound like ESU makes bulletproof decoders (or that you have a perfectly wired layout). I also prefer just to use LEDs and never worry about having to replace them (in my lifetime). Yeah, the color might not be perfect but so isn't the scale diameter of the handrails and many many other parts of the model. We live with compromises - there is no perfection. :-) Peteski > To each its own... Correct. > I work with computers so I don't trust any consumer-grade electronics. > Especially ones driven by microcontrollers with possibly buggy > firmware. And ones greatly affected by voltage spikes and other > assorted DCC wiring ailments. You make it sound like ESU makes > bulletproof decoders (or that you have a perfectly wired layout). And your experiance with ESU decoders are ? Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe On May 17, 12:55 am, "Klaus D. Mikkelsen" <er.du.saa.k...@du.kan.gaette.den> wrote: > > To each its own... > [quoted text clipped - 9 lines] > > Klaus Absolutely none except for those very positive reviews I see everywhere. :-) I'm glad that you've found a perfect decoder! I do have general knowledge of electronic components - I have to assume that ESU decoders use components similar to other equivalent DCC decoders. So, in my experience they are would not be totally bullet proof. If you're experience shows otherwise so be it. I'm not arguing that point - I still wouldn't trust a DCC decoder to directly power a 1.5V bulb. That's just me. Peteski > On May 17, 12:55 am, "Klaus D. Mikkelsen" > <er.du.saa.k...@du.kan.gaette.den> wrote: [quoted text clipped - 25 lines] > > Peteski Powering a 1.5 volt bulb isn't difficult: - PWM. - series reesistance. (causes generation of heat) - voltage regulator. (causes generation of heat) - parallel diodes to limit voltage. Greg.P. On 5/19/2008 7:41 PM Greg Procter spake thus: >> I do have general knowledge of electronic components - I have to >> assume that ESU decoders use components similar to other equivalent [quoted text clipped - 8 lines] > - voltage regulator. (causes generation of heat) > - parallel diodes to limit voltage. You're missing the point, as usual; he's saying that while it's a piece of cake to power a 1.5V bulb, he wouldn't trust a DCC decoder to do it safely. All you need is one glitch and poof! no more bulb. SignatureThe best argument against democracy is a five-minute conversation with the average voter. - Attributed to Winston Churchill > On 5/19/2008 7:41 PM Greg Procter spake thus: > [quoted text clipped - 16 lines] > > All you need is one glitch and poof! no more bulb. Well now, not quite so fast with that statement. PWM, Yes you are right! series resistance ---- no problem possible, as even a 'glitchy' DCC decoder isn't going to generate MORE voltage that allowed for with the series resistance. voltage regulator ---- no problem possible (see above --series resistance) parallel diodes ---- they don't care what voltage is available (as long as it's more than 2 ~ 3 volts. Chuck D. > voltage regulator ---- no problem possible (see above --series resistance) Exactly, which is why a week ago in this very thread I suggested the TCS A6X. As I mentioned in that post, the A6X has an on-board 1.5v constant voltage regulator. *Not* resistors, but a constant-voltage regulator. It's unaffected by the varying current draw of those notoriously inconsistent Genesis 1.5v bulbs. On the other hand, those varying current draws make resistor selection a crap shoot. Stevert On 5/20/2008 6:05 AM Stevert spake thus: >> voltage regulator ---- no problem possible (see above --series resistance) > [quoted text clipped - 7 lines] > inconsistent Genesis 1.5v bulbs. On the other hand, those varying > current draws make resistor selection a crap shoot. This *sounds* like the best solution. Sorry to seem nitpicky, but I still wonder how reliable this is. Why? Remember that a voltage regulator works by "burning off" the difference in voltage between source and load, which in this case is considerable (12 - 1.5 = 10.5 volts). That excess voltage has got to go somewhere, which it does in the form of heat. I just wonder how big the regulator on the decoder is, and if it's capable of dissipating that much power continuously without failing. Do you know what the 1.5 volt output is rated for? (Tony's Train Exchange says the decoder has six 200 ma function outputs, but I don't know if that includes the 1.5 V output or not.) Other than that, yes, it's the best way to go. SignatureThe best argument against democracy is a five-minute conversation with the average voter. - Attributed to Winston Churchill >(Tony's Train Exchange says the decoder has six 200 ma > function outputs, but I don't know if that includes the 1.5 V output or > not.) The functionoutputs are most likely "sink" outputs, where the output is open circuit when not activated and connects to "ground" when activated. Klaus SignatureModelbane Europas hjemmeside: http://www.modelbaneeuropa.hadsten.dk Modeltog, internet, gratis spambekæmpelse, elektronik og andet: http://home6.inet.tele.dk/moppe > On 5/20/2008 6:05 AM Stevert spake thus: > [quoted text clipped - 24 lines] > > Other than that, yes, it's the best way to go. You'll probably find that the 1.5 volt output is the full 18 volts delivered 1.5/18 of the time by PWM. Regards, Greg.P. > On 5/20/2008 6:05 AM Stevert spake thus: > [quoted text clipped - 25 lines] > > Other than that, yes, it's the best way to go. If you tried to run 200ma loads on all six functions through the regulator at once, yeah, it might get warm. But those stock Genesis bulbs are only what, 20ma each? I haven't found heat or reliability to be a problem, even with 6 of those bulbs (SD70 w2 front, 2 rear, and 2 ditch lights). Stevert > > voltage regulator ---- no problem possible (see above --series resistance) > [quoted text clipped - 9 lines] > > Stevert Place a pair of series diodes in parallel with your bulb(s). The series resistor will then drop the remaining voltage, leaving a constant 1.4v across the bulb. A constant voltage regulator will have to drop the same wattage under DCC supply and will require considerably more additional components. Greg.P. >>> voltage regulator ---- no problem possible (see above --series resistance) >>> [quoted text clipped - 17 lines] > > Greg.P. After reading your post a couple times, it dawned on me that you must have missed the point about the regulator already being *on-board* the A6X. There are, in effect, no "considerably more additional components" that I need to be concerned with. TCS has already taken care of that. And if I add diodes and resistors, especially for multiple bulbs, aren't those "more additional components"? And what about the complexity they bring along: More solder joints, having to insulate all that junk, the physical space issues, etc. I buy the A6X, drop it in, solder the connections (minus any resistors or diodes) and I'm done. No muss, no fuss, and no burned out bulbs. What does your solution buy me over the A6X? Stevert > >>> voltage regulator ---- no problem possible (see above --series resistance) > >>> [quoted text clipped - 33 lines] > > What does your solution buy me over the A6X? Absolutely nothing if you're happy with the A6X 1.5 volt lighting output. If you're not prepared to use the A6X 1.5 volt lighting circuit then you will want an alternative. A resistor and 4 diodes is a lot simpler than a stand alone voltage regulator circuit and will achieve the same result.. Regards, Greg.P. On 5/20/2008 4:11 PM Greg Procter spake thus: >> After reading your post a couple times, it dawned on me that you must >> have missed the point about the regulator already being *on-board* the [quoted text clipped - 18 lines] > A resistor and 4 diodes is a lot simpler than a stand alone voltage > regulator circuit and will achieve the same result.. Now I'm puzzled too; if one had an A6X, why would one *not* want to use the 1.5 V output (assuming you're driving 1.5 V bulbs)? SignatureThe best argument against democracy is a five-minute conversation with the average voter. - Attributed to Winston Churchill > On 5/20/2008 4:11 PM Greg Procter spake thus: > [quoted text clipped - 23 lines] > Now I'm puzzled too; if one had an A6X, why would one *not* want to use > the 1.5 V output (assuming you're driving 1.5 V bulbs)? To provide a puzzle to those who try (unsuccessfully at times) to have the last word! Chuck D. > To provide a puzzle to those who try (unsuccessfully at times) to have > the last word! > > Chuck D. Zymoscope. (At least according to my dictionary.) Puckdropper SignatureIf you're quiet, your teeth never touch your ankles. To email me directly, send a message to puckdropper (at) fastmail.fm > > To provide a puzzle to those who try (unsuccessfully at times) to have > > the last word! [quoted text clipped - 8 lines] > > To email me directly, send a message to puckdropper (at) fastmail.fm Gee, my little "The Little Oxford Dictionary" lists "zymotic". ;-) Regards, Greg.P. > On 5/19/2008 7:41 PM Greg Procter spake thus: > [quoted text clipped - 14 lines] > of cake to power a 1.5V bulb, he wouldn't trust a DCC decoder to do it > safely. All you need is one glitch and poof! no more bulb. Sure, and the light in his fridge might not go out when he shuts the door. |
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