EZ-Command track voltage too high?

[Maletrain]

When messing around with some old Bachmann passenger cars apparently designed for 12 VDC operation, which had excessively bright lights on my DCC layout, I found that my Bachmann EZ-Command DCC unit (Item No. 44901) is putting 19.4  volts AC (rms) on my tracks.  That seems strange, because the transformer that powers it is putting out 16.4 volts AC (rms), very close to its specification of 16.0 volts.  House voltage at the time was 120.7 volts AC (rms).

This concerns me somewhat, since I have read that some LED lighting kits are only good for 18.0 volts AC (peak), which is close to 16 volts AC (rms).  Worse, apparently Kato engines are only warranted for track voltages below 18 volts peak.  So far, I am only running Bachmann engines, which I PRESUME are OK with a Bachmann DCC unit.

So, I am thinking that I should settle on a control system before I go any further into engines and car lighting. 

Any other Bachmann DCC units that hit their track voltage specifications better?  Or, is there a relatively inexpensive DCC unit from another vendor that I should upgrade to?

[skipgear]

The Bachmann system voltage is a lot higher than I like to see. The accepted norm for N scale is to keep max voltage at around 12V. It's easier on motors.

[Maletrain]

I bought a RRampmeter and properly measured the DCC voltage from my Bachmann EZ-Command on my track near the feed point.  It is 17.9 volts. 

I understand that I should install some diodes in series to provide a voltage drop that is independend to current.  Any suggestions on specific diodes from Radio shack or elsewhere to get the voltage down to something closer to 12 volts?

[richg]

Make a test set-up on the bench with a motor and a couple 12 volt light bulbs.
A 1k resistor and LED will work. Measure the DC voltage right at the decoder connections.
What do you see for DC voltage for the lights.
What do you see for DC voltage to the motor at speed step one? The motor will get pulse power but the meter will see it as a DC voltage. A Scope will show the max voltage of the pulse.

I have done this with my Power Cab that has a DC power pack with 13.9 VDC. I see about 12.2volts DC for lights.

Rich

[Joe Satnik]

Dear MT,

Here is an old "Shorted Diode Bridge" (for dropping voltages in both directions) thread:

http://www.bachmanntrains.com/home-usa/board/index.php/topic,16727.0.html

Read down to at least the bottom of the first page.  

The Radio Shack diode bridge shown is 8A, probably overkill, but I think that

the Radio Shack bridge of only 1.5A might not survive a direct short across the rails.

Not sure they have anything at the store in between.  

Hope this helps.  

Sincerely,

Joe Satnik  

Edit:  Added "across the rails".