Why set throttles to max?

Don In the command environment you're not obligated to apply full transformer power. Some dial it back to 15-16v to preserve light bulbs. Electocouplers may fail to fire if you drop too low. Not sure these few volts will help if a loco were to take off but the chance of that is pretty rare.

Interesting question.  I am new to this stuff and am using a MRC 270 watt transformer with walk around controls for power.  The variable voltage terminals did not agree at all with TMCC.  I don't know why.  To correct the issue I used the 14V fixed outputs and have had no issues at all.  Since the layout was already set up for block control one side is wired to the fixed 14 V and one to the variable throttle.  That way I can run either conventional or TMCC.  Seems to work for me.  One unintended benefit so far was the day I selected the fixed voltage but had a conventional loco on the track. The loco took off but slow enough to prevent a disaster.

I have an MRC PurePower 270, and it works fine for TMCC and DCS.  It's pretty much very similar to any pure transformer, a big toroid with variable voltage taps on the secondary, just like any PW Lionel transformer.  I can't imagine why it wouldn't work for TMCC.

A higher setting will result in lower voltage drops/losses between track feeds and a lower overall current drain.

 

If TMCC and DCS were based on a 220 volt track power supply, we could power entire large layouts with 24 gauge  and smaller bell wire.

 

Likewise, if our cars were 120 volts instead of 12, the battery leads would be about the size of lamp cord.

Touching the track would be a bit unpleasant though.

 

I would not run the system lower than the recommended voltage. The reason is some of the solid state devices driving the motor in cruise for example may have amperage ratings. Say a trains is set on cruise and pulls a heavy load and requires 100 watts to pull it and maintain speed.  That would be around 5.5 amps at 18 volts. Dropping from say 18 volts to 13 volts would require over 8 amps to get the same 100 watts of power. That may be more amperage than the Traic or whatever is rated for. It may shut down or burn out.

 

Dale H

Good point Dale, and another issue is on many of my locomotives the electrocouplers will not fire on 15-16 volts anyway.

OK, I do want electrocouplers so for the track with TMCC loco (when i get one)will get full throttle.

  Thanks; Don

I have set my TMCC TPC to 16.2 volts because I have a Ross double crossover with relays wired a certain way for best operation through the switch, and if I run over the crossover the wrong way I have fried a few relays running at 18 volts.  If I cheese out now, I don't fry a relay.  I've never had a coupler not fire.  If you are running a triple lashup MU consist on one loop and start a double or triple on the second loop, there is a drop in power to the first MU lashup consist.  But that is the only negative, and it's neglible and easily corrected, and the benefit of having a lower voltage to save replacing a z stuff relay with it's seven skinny annoying wires outweighs the negative.  I'm still all TMCC, with a few Odyssey equipped engines.  I'm going to stay at 16.2 for now.

You can put a diode dropper to the coils described here or a resistor in series to the relay coil.

 

www.jcstudiosinc.com/BlogShowT...=413&categoryId=

 

Dale H

Hi Dale - you talkin' to me? (looking over my shoulder and around the room)

If the sketch and the pic of the wiring rat's nest were intended to invoke an interest in using a diode to further my enjoyment of this great hobby, I dare say it may have had the opposite effect.  But, maybe not.  Just the fact that I've gotten this far in the thought process may have created a spark to further my interest.  Thanks for that.  Cheers 

I would run the system at full voltage and then set the speed limit for each command locomotive independently.

Ron

set the  speed llimit for all locos and then no worry of too fast.  my full throttle starts with a number 7 momentum are great  and most engines are set to about 92 to 110 speed steps max,.

Hi William

 

Here is a neatly made diode dropper,for what you are doing you could use 1 amp diodes

 

www.jcstudiosinc.com/BlogShowT...=488&categoryId=

 

The previous post pic looks messy because I made it have adjustable taps. The camera picked up all the red wires but it is not that disorganized. It is a complete throttle for a loop of trains made with 25 amp bridge rectifiers that is powered directly off a Lionel brick.

 

Here is a view of the dropper from a distance,a little more organized along with timers,relays and a whistle/bell sequence circuit. Starts with 6 pairs of diodes then the bridges are used.

 

 

 

 

Dale H

Yes, it's all so much clearer on a Friday evening after an hour or two at the pub.  I will digest this with another beer and report back in the morning.  Time to run some trains. Cya 

Please note the "full ON" is not the same for all sources.

 

Postwar transformers and Lionel bricks connected directly to the track provide a full sinewave without any gaps or glitches.

 

On the other hand, a modern ZW, CW-80, Powermaster or TPC will always have some form of notch in the waveform, even at maximum ON.  This deliberate gap is used to make the dc offset to blow a horn/whistle or ring a bell.