Multimeter Readings - DCC Track Voltage?

[Right Away]

Just a little poser for thought.

 

The Set Up:

• 10 year old Lenz DCC which works perfectly. 
• Track supply configured on system at 14v.
• I replaced my old Victor 86D multimeter as a crack had appeared in the display screen, although most characters are still legible. 
• The new meter is a DiLog DL9206.

 

A random check of the track voltage produced the following disparity of readings between the two meters.

Victor 86D: reading fluctuating between 14.18v and 14.40v

DiLog DL9206: reading fluctuating between 20.82v and 21.19v

It is appreciated the output from any DCC controller is not of a pure sinusoidal AC waveform.

 

Never given this much thought before as the DCC works fine, but it would appear the Victor meter could be showing an RMS value (of sorts]? There is nothing to suggest it does. However, dropping these figures into an online RMS calculator would seem to show that this is indeed the case as the results are very close.

 

Some may find this worth bearing in mind if having just invested in their first meter when checking DCC track voltage.

 

[RAF96]

DCC signal from memory is around 10MHz. The accuracy of any meter reading on the AC Volts scale will depend upon the meter sampling frequency.

I have three meters (ancient to modern) with vastly different rates and they return vastly different readings.

For true DCC voltage readings you need a relatively expensive (£50) RRAMP meter.

Edited August 27, 2021 by RAF96
Typo

[spamcan61]

We've had similar discussions before on this topic, see followng thread for example:-

 

 

[Crosland]

5 hours ago, RAF96 said:

DCC signal from memory is around 10MHz.

 

Your memory is failing you  It's just under 9kHz.

[AndyID]

9 hours ago, RAF96 said:

DCC signal from memory is around 10MHz. 

 

The FCC and Ofcom wouldn't be too happy if it was