Atlas SW9 Speaker

Hi Bob.

Yes, that's the connector I was looking for.  I wasn't sure whether you used a NEM652 connector (such as offered by NCE for instance, to get the 0.100" plug spacing) and split it into two or cut up a strip as you have stated.  I was under the impression (perhaps falsely)  that gold plated connectors were the "gold" standard and therefore was trying to find one like the one you had used.

Thank you again for your attention and quick response.

Sincerely,

Stephen

Good call.

I tried using an HO decoder myself on a Weaver GP 38-2, Bob.

I changed it out because I was getting moaning noises from the motor.  The L series didn't make any difference.

I could have stayed with the V4 Select. 

Max -

The older Weaver G 38s with a horizontal Pittman motor and chain drive used a standard 8xxx-series 12 volt winding that stalls around 8A. On the A&O with heavy coal trains, steep grades, and extra lead weight in the locomotive, we would kill an HO decoder in a hurry. I've never tried a later Weaver with twin motors a/k/a "China drive."

By the way, the moaning sound happens when a back-EMF decoder momentarily turns off power to the motor so that it can estimate rotation speed by measuring the motor's back-EMF (or generator) voltage. Changing the Back-EMF Sampling period [CV10] in LokProgrammer changes the sound from a low moan to a much higher singing note.

All the best.

You're right, Bob.

The moaning sound was only reduced when I changed to a P&D drive with one of those adjustable towers. 

The whole sad story is here . . .

https://ogrforum.com/t...first-attempt?page=1

Cheers

So much great info in this thread - thanks everyone!  

FWIW I have HO Tsunami V1s in 2 Atlas China Drive GPs with no issues for a couple of years. Also a Dash 8-40B with HO Loksound Select for the last year. And as mentioned above, HO Selects in Atlas MP15DCs. As well I have an SW9 with HO TCS WOW Diesel v3, and a C&LS RS-11 with TCS WOW HO. I might change that one to Loksound now, better for consisting I find. All have LED lighting throughout and the Tang Band 1925. Basically everything I learned from shamelessly copying Bob's work.     

No issues with any of these locos pulling up to 20 x 1 lb cars on level track with about 14.8V track voltage. Note I don't have the grades or train lengths of the A&O so my loads are way less. My locos are weighted to about 4-5lbs but I make sure they all get to wheel-slip before stalling. The Atlas China drives I have don't draw more than about 1A with both motors stalled. A 3-unit consist (6 motors) draws about 2.5A altogether at wheelslip. These numbers are according to my in-line RRAmpmeter. I know that's not the same as measuring the current from the decoder to the motor but I think it's quite close. 

Please comment on this Bob as I am no electrician!         

Hi, Pete. I am a geek, a retired electrical engineer. So to answer your question...

The RRampMeter displays the current and voltage going into the decoder, not the current going out to the motor. At times they are anything but close. Say what?

OK, what. As it turns out, a DCC decoder in conjunction with the inductance of the motor armature coils behave somewhat like a switching power supply. The decoder modulates power to the motor by rapidly switching the voltage on and off, usually above 20 kiloHertz so we can't hear it singing. A high voltage at low current goes in, and a lower average voltage at higher average current comes out.

Under a certain condition, let's pick half-throttle (and ignore lots of details for the sake of simplicity) we might have 14 volts going into the decoder. Out of the decoder's power supply and switching motor drivers we might get a maximum of 12 V due to inevitable circuit losses (again ignoring lots of details.)

Now suppose the RRampMeter shows 1A going into the decoder. The "switching power supply effect" transforms 12V at 1A to an average of 6V at 2A (ignoring losses.) In our simplified example the same amount of power comes out of the decoder (Volts times Amps) as goes in. The average motor voltage is half  but its average current double of what goes in to the decoder. It is the current fed to the motor that matters to a decoder.

As for HO vs O scale decoders, I know of many modelers who have enjoyed success with the smaller decoders in their locomotives, as you have. Most of the time operating conditions are probably not sending the decoders into deep overload. Putting a little momentum in every locomotive can help, so that there isn't a massive current spike when someone fumble-fingers a throttle and tries to send a running train into instantaneous reverse (this isn't good for train handling either...) Not running at "ludicrous speed" (Spaceballs the movie reference) can also help.

On the former A&O, there was once a 40 car coal train, each car weighing 2.2 pounds with live loads, going up about a 3.5% compensated grade. Those operating conditions were different. During testing on the new A&O I watched a weighted P&D F unit draw about 1.5A on our analog version of an RRampMeter, at wheel slip and about half throttle, trying to shove a long cut of cars up a steep grade. During that test the Pittman motor quickly got uncomfortably hot, even with the shell removed.

Through a mutual friend I asked Matt Herman of ESU USA whether a Loksound HO decoder would survive in an Atlas SW9. He indicated that it had been tried but the decoder failed. I did not receive any details of the operating conditions. 

"Your mileage may vary."

Thanks, Bob.  I am enjoying your explanations.

I also put a Loksound L into my Atlas SDP 35.  The China drives are a real pain to get to run slowly.  I've wired them in series, which seems to have helped - but the slow performance is nothing like the single motor tank drive on the Weaver.

The headlight/rear lights come and go, so there must be some overload protection which is playing up.  I mean, how much load can a couple of LEDs put on it? 

Anyway, thanks again for your writings.

Cheers

riogrande491 posted:

Hi, Pete. I am a geek, a retired electrical engineer. So to answer your question...

The RRampMeter displays the current and voltage going into the decoder, not the current going out to the motor. At times they are anything but close. Say what?

 

Thanks for the detailed response Bob! I see now how particular scenarios could cause massive current flow. Fortunately for me I do have CV3 set very high on all my locos, and all are set to top speed of about 30 scale MPH. So at least that helps me to (unwittingly) avoid a couple of the scenarios you describe.    

One thing I forgot to mention is that all my HO decoders, Tsunami 1, Loksound and TCS WOW have the TCSKA2 added. I get about 4-5 seconds of running with sound and LEDs on from each decoder type. Would that have any benefit regarding the scenarios you describe? 

Max: That's odd about your LEDs coming and going. Did you end up fitting a Keep Alive? I can't remember, sorry. I do have powered frogs and feeders to switch rails as well as closure rails. Post KA2s, the yard job on my layout goes up and down the 6 turnout yard ladder for a 3 hour ops session with nary a flicker.  Before the KAs, it was more like random strobe headlights even with "DCC friendly" turnouts.   

Hi Pete

It's a recent phenomena.  Sometimes I'll turn the layout on and I've got front and rear lights and one or the other will die - or both.  At the moment neither of them are working.

Sometimes I start up and the lights will be off and then they come on again.

I don't have keep alive capacitors.  I keep the wheels and rails clean and don't have a problem.

I understand that the LS L has a basic stay alive capacitor on the board.  That does the job for me.

I suspect that I might have a faulty decoder.  I have a spare one, so I'm going to swap them over when I find some time.

Cheers

Of course, the L has KA built in, I forgot that too.  

I hope it's an easy fix and not some hidden wiring issue. I had a pre-wired LED in one of my MP15DCs with a tiny nick in the insulation that would just tickle the diecast frame once in a while and cause a flicker or a short. Took me a while to find that one.. 

Thanks, Pete.

Question for Bob......do you recall the thickness of styrene you used to form the platform to hold the speaker and decoder?

Thanks,

Stephen

Probably 0.040". The area under the speaker was built-up so that the speaker would not hit the head of the M3 screw.

I need to bring this thread up for info. I want to install ps3 into one of mine for a test. I am looking at many available speakers now. Seems like there's so many more.

I forgot to order the tang band to try.

Here's a quick update after 5 years have transpired. Fellow A&O modeler Rick Bacon upgraded his Atlas SW1200 using scratch built parts and many etchings from Kaiser Valley Models. Inside he installed a Loksound 5L and a TB 1925 speaker module. He thought perhaps he could fit a 1931 but opted for the easier 1925 install. He added acoustically-transparent simulated radiator cores. It looks, sounds and runs great. When I eventually rework my SW9, I plan to upgrade to a 5L and TB 1925.

Link to Rick's 1200:

https://ogrforum.com/...r-sw8-9-1200-windows

After I shot the photos of my SW1200, I cut off the speaker mounting tab and installed a small ESU PowerPack between the speaker and decoder. That helped a lot with dirty track or wheels when the unit is used for switching cars in yards.

Speaker quality became better, IMO.  One problem with TMCC, (Atlas) was the speaker came-on at full volume, which may have cause several speakers, to fail.  Another problem was, the speaker, (a relatively large magnet), would pick, metal debris from the road bed.  Edit/add: The metal debris, on the speaker face, distorted the sound/added a crackle-ing.   One of those, who would'a thunk???? IMO, Mike CT.