How to use a Multimeter with DCC.

[Baby Deltic]

 

 

 

[SHMD]

I think a "moving Iron" analogue meter will read the DCC track voltage correctly.

Or was it a moving coil... no... wait...no. No...... I'll look it up.

 

I'm pretty sure I have the same meter somewhere but mine is yellow.

I'll try to find it and compare it with my Fluke 87 workhorse - which replaced the 'cheap' meter decades ago!

 

My fluke reads 13.73v AC across my DCC tracks which are being fed with 15.00v, (via an L298 H-Bridge), so about right.

(My scope shows 14.0v Pk-Pk - flat but there is some flyback and I haven't taken into account any the rise and fall time.)

 

I'll check as I'm interested myself.

 

 

The important thing is to use the meter now - when there are no problems - so that when you do have a problem then a/ you know how to use the meter, and b/ you know what the 'normal' readings should be and so don't have to try to second guess everything.

 

 

Kev.

[SHMD]

I couldn't find the meter that was similar to the OP's.

(I looked everywhere - except where it actually is!)

 

These are 3 meters that were connected to the DCC tracks.

The Fluke 87 is good and very trustworthy. The HIOKI is cheap small and 'slow'. The HT-320 is ancient - well 1980s.

 

The DCC is being generated by my 2012 Innovation entry - SDB1.

This was basically an PWM DC controller with expansion possibilities. One of these possibilities was to drive DCC. This is what I am doing now.

The SDB1 is supplied by a bench power supply. This is why I can manipulate/control all aspects of what happens on my test plank.

 

Adjusting the PSU volts, to the DCC controller, I was able to obtain the following results:-

 

 

Conclusion :- just measure the DCC voltage with whatever meter you have BUT get used to it what it looks like first!

 

 

Kev.

PS. Never NEVER leave your meter in the current measuring mode!