Greg, or anybody with sufficient electrical experience, could you translate into English what these folks are trying to tell me?
http://ogrforum.ogaugerr.com/topic/older-vs-newer-transformers
Thanks.
You first need to define what a “transformer” is. Are you talking about the actual power pupply that puts out a fixed voltage and is then “adjusted” using a separate hand unit (e.g., AristoCraft Ultima or Meanwell), or a “power pack” all-in-one unit like an MRC 6200, or both/either?
But I would say that there are certainly some units, by design, that can damage delicate electronics even without overpowering them due to excessive “non-loaded” voltage.
The MRC 6200 is such a beast. When I design circuitry, I’ve seen it operate perfectly with batteries, fine on the track power (Meanwells/TEs on linear), and fry the 555 chip using the MRC on the bench.
Yes, many older power supplies (transformers), aren’t regulated. So they say the output is (just to pick a number) 20 volts DC, but with no load on the output, a meter may read 35 volts DC. If you send the no load voltage into your electronics they can fry. Sierra even warns about that in their instruction handbook. So what those guys are doing is putting the TVS across the output of their power supplies, to ground out that high voltage so they don’t fry anything.
Also, with pulse width modulation, the power supply doesn’t reduce power by reducing the voltage output, it reduces the power by making the on pulses narrower, or the off pulses wider, or both. So the electronics “sees” full power, no power, full power, no power…some electronics can be fried that way too. I fried a Sierra board that way, even though it was not supposed to be fryable that way.
Pretty hilarious reading Steve.
First from the links you provide, these are all AC transformers, although some of the old Lionel stuff were autotransformers.
Then they spend a lot of time talking about TVS, transient voltage suppressors, which can be MOVs or other devices, the whole idea is to limit unwanted voltage spikes.
I’m figuring that the voltage spikes can kill some of the newer Lionel electronics, whereas the old stuff was just big motors and light bulbs.
None of the transformers mentioned were regulated, they were true transformers. I see that Todd and David did want to address the common habit of referring to ANYTHING that provides power as a transformer in the hobby.
But that’s not what the link you provided is about, from my reading of it and several other linked threads.
The only difference I could find between “old” and “new” was the transient suppression, they are apparently all true transformers, i.e. 2 coils of wire that are called primary and secondary, an iron core of some type, and use for AC, stepping home line voltage to the voltage desired by the AC powered trains.
Does that help Steve?
Greg
Greg, yes the often misused term of “transformer” was a can of worms I didn’t feel like opening. But by distinguishing if we are talking about a transformer, power pack, or controller, would certainly help shed some light on the subject, and help us to more accurately answer the question.
I guess I should have been specific, but I thought that the header of O Gauge Railroading would have been a tip off, like it was for Greg.
Yes, there is a difference between the older, post war transformers, and the newer ones that came out with TMCC and DCS. The newer ones have built in fast blow circuit breakers that protect the electronics in the locomotives, where the older ones only have slow blow circuit breakers that protect the transformer.
As to the transient suppression mentioned by Greg, I don’t have the foggiest idea, I’m not trusted with a light switch.
My goal is to run the modern locomotives with reconditioned prewar transformers, with a quick blow 5 amp (maybe 3 amp) circuit breaker in both the positive and common lines. I suppose that’s over kill, but circuit breakers are cheap, and those damn boards in the locomotives are spendy. This will be indoors, in the basement, of course. I have a line on some KW’s and ZW’s, reconditioned, for reasonable.
OK, I’ve read the OGRR thread again, and if I understand it correctly, the transient voltage suppressor is needed to suppress the occasional spike in voltage. I understand why the TVS wouldn’t be necessary in the Post War stuff. The TVS protects the modern 0 Gauge locomotive with the TMCC or DCS or Legacy by adsorbing any voltage spike created by a short circuit, such as one created by a derailment.
Question: With the newer transformers, why is this necessary, since the PC boards in the locomotives would be sensitive to such a spike? Yet the thread insists that they are necessary, even for the newest ZW and Z-4000. Is this a marketing ploy on the part of Lionel and MTH to increase sales? Perhaps I shouldn’t be so cynical.
Question: If even a fast blow circuit breaker only protects the transformer, does it also protect the locomotive by its speed? Should there be a resetting circuit breaker installed in the locomotive, like Aristo did? IS there?
Steve, a circuit breaker will blow when too much current is demanded from the power supply, it doesn’t care how much voltage is there. The TVS will clamp down the voltage so that the electronics in the locomotive don’t fry. They are 2 different animals exhibiting 2 different behaviors. The TVS on the thread you linked don’t appear to be all that expensive, and for cheap insurance why not put them in?
I plan to, David. The more I ponder this stuff, the less muddy it seems.
Steve, that can be said about a lot of things.