Best Decoder for Athearn F3

As always, you are correct! No need to propagate even the slightest misinformation on a toy choo-choo forum. :-)

Peteski

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

"Peter W." skriver:

Correct.

And your experiance with ESU decoders are ?

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

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:

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.

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.

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:

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.

David Nebenzahl skriver:

The functionoutputs are most likely "sink" outputs, where the output is open circuit when not activated and connects to "ground" when activated.

Klaus

Sure, and the light in his fridge might not go out when he shuts the door.

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.

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.

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

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

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:

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.

Charles Davis wrote in news: snipped-for-privacy@enews2.newsguy.com:

Zymoscope. (At least according to my dictionary.)

Puckdropper