Topics

Remote RRamp-like Indicators

Gregory Latiak
 

When I built the control panel for my layout I included an RRamp meter in-line to monitor power draw on the track. Due to an influx of sound locos I have been forced to add an additional booster and partition the track feeds. I would love to have a meter on both booster supplies -- but have no space to add a second RRamp circuit board. And I have considered but rejected ideas to switch the meter between the boosters as this would cause interruptions in track power that I would prefer to avoid.


Is there anything out there that I could use to provide equivalent power and voltage metrics where the display could be some distance from the circuitry? I would prefer to not scratch-build but would if necessary. (I did ask the RRamp people but they suggested switching it...).


I have also considered unsoldering the display and moving it to the end of a ribbon cable. Not sure I am feeling that bold, but...


Any thoughts or suggestions?


Thanks,


Greg Latiak

Vollrath, Don <dvollrath@...>
 

Greg,

If you want to permanently monitor booster output ampere demand, why not simply add one at each booster? See http://www.wiringfordcc.com/track.htm#a4 . Inexpensive multimeters with a digital DC ammeter readout are available at Harbor Freight and other discount suppliers.  

DonV

 

From: WiringForDCC@... [mailto:WiringForDCC@...]
Sent: Wednesday, March 09, 2016 7:45 AM
To: WiringForDCC@...
Subject: [WiringForDCC] Remote RRamp-like Indicators

 




When I built the control panel for my layout I included an RRamp meter in-line to monitor power draw on the track. Due to an influx of sound locos I have been forced to add an additional booster and partition the track feeds. I would love to have a meter on both booster supplies -- but have no space to add a second RRamp circuit board. And I have considered but rejected ideas to switch the meter between the boosters as this would cause interruptions in track power that I would prefer to avoid.

 

Is there anything out there that I could use to provide equivalent power and voltage metrics where the display could be some distance from the circuitry? I would prefer to not scratch-build but would if necessary. (I did ask the RRamp people but they suggested switching it...).

 

I have also considered unsoldering the display and moving it to the end of a ribbon cable. Not sure I am feeling that bold, but...

 

Any thoughts or suggestions?

 

Thanks,

 

Greg Latiak




Gregory Latiak
 

Well, I would except that the space available is barely larger than a single RRamp circuit board. I guess I don't really understand the issue of correctly measuring booster output -- I would speculate (and please correct me) that current flow should be straight forward, but voltage measurement for the DCC waveform is probably 'interesting'. I have a cased RRamp that I use for spot checking the track, so I probably don't really need running voltage from the booster or the idiot lights. If it ain't DCC coming from the booster than I probably have other issues.

Anyhow, if a regular digital amp meter will provide a reasonable value then I am probably ok with that.

greg

Mark Gurries
 

The complexity of the voltage waveform is the same for the current waveform.  Both are bipolar pulses.  A waveform that the most common DVM meters are not designed to read correctly.  The bridge rectifier removes the bi-polar nature of the rectangular waveforms to a unipolar output.  Given the waveform is a rectangular, the end result is that the rectifier converts the rectangular AC to 99% DC which any meter can measure accurately.

As Don said, there is calibration issue when reading voltage.  You ave to account for the two diode voltage drops.

For current, the bridge rectifier does not introduce an error term but does reduce the final track voltage by two diode voltage drops.   If a locomotive crosses a booster district where the track current is NOT monitored to one that is monitored, you can see the engine speed change.    However, higher end DCC decoder with BEMF motor drive will minimize/compensate for that effect.

Taking a step back, I am always wondering why people think is it important to monitor the booster voltage and current.    If you think it will give you a heads up on booster overload, that is not what actually happens.  Most overload problem are not related to train running issue.  They are recovery from a short circuit while dealing with high inrush current issues.


On Mar 9, 2016, at 9:57 AM, glatiak@... [WiringForDCC] <WiringForDCC@...> wrote:

Well, I would except that the space available is barely larger than a single RRamp circuit board. I guess I don't really understand the issue of correctly measuring booster output -- I would speculate (and please correct me) that current flow should be straight forward, but voltage measurement for the DCC waveform is probably 'interesting'. I have a cased RRamp that I use for spot checking the track, so I probably don't really need running voltage from the booster or the idiot lights. If it ain't DCC coming from the booster than I probably have other issues.

Anyhow, if a regular digital amp meter will provide a reasonable value then I am probably ok with that.

greg

Best Regards,

Mark Gurries
Electrical Engineer
DCC Website & NMRA DCC Clinics: www.markgurries.com



Mark Gurries
 

I should say the bipolar current waveform that although is rectangular is NOT in any time sync with the DCC voltage waveform.  The current pulses come from decoders that are actively driving motors with pulses (PWM) asyncrounsly with the DCC voltage waveform.  it is a random composite of all the decoder motor current pulses that are running.  But the end result through the rectifier is still DC although pulsed DC….the meter will report the AVERAGE value of the collective current pulses.  It will NOT report the peak current which is what the booster monitors.

On Mar 9, 2016, at 11:11 AM, Mark Gurries gurriesm@... [WiringForDCC] <WiringForDCC@...> wrote:

The complexity of the voltage waveform is the same for the current waveform.  Both are bipolar pulses.  A waveform that the most common DVM meters are not designed to read correctly.  The bridge rectifier removes the bi-polar nature of the rectangular waveforms to a unipolar output.  Given the waveform is a rectangular, the end result is that the rectifier converts the rectangular AC to 99% DC which any meter can measure accurately.

As Don said, there is calibration issue when reading voltage.  You ave to account for the two diode voltage drops.

For current, the bridge rectifier does not introduce an error term but does reduce the final track voltage by two diode voltage drops.   If a locomotive crosses a booster district where the track current is NOT monitored to one that is monitored, you can see the engine speed change.    However, higher end DCC decoder with BEMF motor drive will minimize/compensate for that effect.

Taking a step back, I am always wondering why people think is it important to monitor the booster voltage and current.    If you think it will give you a heads up on booster overload, that is not what actually happens.  Most overload problem are not related to train running issue.  They are recovery from a short circuit while dealing with high inrush current issues.


On Mar 9, 2016, at 9:57 AM, glatiak@... [WiringForDCC] <WiringForDCC@...> wrote:

Well, I would except that the space available is barely larger than a single RRamp circuit board. I guess I don't really understand the issue of correctly measuring booster output -- I would speculate (and please correct me) that current flow should be straight forward, but voltage measurement for the DCC waveform is probably 'interesting'. I have a cased RRamp that I use for spot checking the track, so I probably don't really need running voltage from the booster or the idiot lights. If it ain't DCC coming from the booster than I probably have other issues.

Anyhow, if a regular digital amp meter will provide a reasonable value then I am probably ok with that.

greg

Best Regards,

Mark Gurries
Electrical Engineer
DCC Website & NMRA DCC Clinics: www.markgurries.com




Best Regards,

Mark Gurries
Electrical Engineer
DCC Website & NMRA DCC Clinics: www.markgurries.com



Richard Gagnon
 

This has been sufficient for our club using the five amp NCE Power Pro. I used the voltmeter circuit with a LED display so we could easily see the reading anywhere in the room.
At home, I used the current option using a Harbor Freight meter on the 20 ma scale. I have four of these meters and they all agree.
I have a high amperage rheostat that I clipped across the track and lower the resistance until the booster trips. Tripped at about 4.97 amps as I recall.

The meters read 13.6 VAC across the tracks and are sufficient for voltage readings. A Scope showed us hardly any spiking.

DCC Ammeter (2010)

  More options below.

DCC Voltages


 

Rich

Gregory Latiak
 

Thanks for this. Looks like something within my skills to fabricate.

greg