Skip to main content

Reply to "Adventures in TMCC & Legacy... Trying to master the 455Khz track signal. I've built the test car, and it is finally working.."

stan2004 posted:
gunrunnerjohn posted:

Correct Dale, my point was simply that it was a DC measurement when you look at it.  Their sample application does have the resistor and cap.

Earlier you said:

I recall them saying when the signal was in the 40's, everything was great.  When the signal dropped down past about 30 and lower, the wheels started to fall off. 

What are the units?

The 455 kHz IC receiver meter output is a current proportional to signal strength with a specified nominal uA per dB slope.  The 51k resistor converts the units to Volts per dB.  The 0.1uF capacitor smooths the voltage.  For average signal strength you want to set the meter to DC Volts.   It's puzzling that the photo shows the meter set to AC Volts?

SS%20Car

 

Hi Guys

Been off from the forum for a week and just picked just up this thread on TMCC/Legacy signal and saw the picture of the earth ground signal test car which I built at the NJ-Hi Railers.  When taking earth ground signal readings you need to be on u amp setting.   When I originally took the picture, I didn't pick up the meter was set for ac volts.   This test car has been a "EXTREMELY USFULL" tool in addressing the TMCC/Legacy signal issues we had on our 30' X 200' layout, as it will indicate where you have week earth ground signal.  Also, when you attempt making changes to improve signal strength, you know right away if what you are doing has helped or not.  I would recommend anyone who is having serious earth signal issues (when you put your hand over the engine, your engine head light goes from nothing/blinking light to a solid on light)  to build one of these earth ground signal test cars which consists of a radio board, resistor & a capacitor.    I posted once before the forum complete plains of making one of these, and if anyone wants I can repost it.  

The other important item, is testing the other part of the TMCC/Legacy signal which comes from the "U" terminal of the command module.  Here we used as mentioned above, an oscilloscope to test signal strength and visually see if the signal was being corrupted by the layout.

Bob D

NJ-Hi Railers

 

Last edited by rad400

OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
800-980-OGRR (6477)
www.ogaugerr.com

×
×
×
×
×