Moving on, do any of you have the ability to test these meters with something that outputs a so-called "chopped" wave? Ex. the Zcontroller, or a CW-80, or ZW-C. I'm curious if they report a reasonably proper RMS reading, or if they get confused by such waveforms.
JGL
I finally got around to trying the voltage car with these 9-12vdc powered, 0-200vac range meters (ebay 390221407367) powered by a Z500 and ZController (see chart below). The voltage car was a few volts lower through the entire range, mid range being the worst and less difference at each end. I used it with 2 different hand held, digital volt meters, because neither of which are top of the line, but both are TRMS. Their readings were within a couple of tenths of each other the entire time so I only recorded the readings from the newest one. 2.3 volts was the lowest I could get the voltage car to read, below that the meter went dark. Probably due to min voltage needed for the AC/DC converter. Looks like the $6 ebay meters are not TRMS.
Voltage Car | | Extech EX205T | | Difference | | Harbor Freight | | Difference |
2.3 | - | 5.3 | - | 3 | - | 2.5 | - | 0.2 |
4 | - | 7.98 | - | 3.98 | - | 4.2 | - | 0.2 |
5 | - | 9.31 | - | 4.31 | - | 5.2 | - | 0.2 |
6 | - | 10.51 | - | 4.51 | - | 6.3 | - | 0.3 |
7 | - | 11.78 | - | 4.78 | - | 7.3 | - | 0.3 |
8 | - | 12.79 | - | 4.79 | - | 8.3 | - | 0.3 |
9 | - | 13.73 | - | 4.73 | - | 9.4 | - | 0.4 |
10 | - | 14.62 | - | 4.62 | - | 10.4 | - | 0.4 |
11 | - | 15.42 | - | 4.42 | - | 11.4 | - | 0.4 |
12.1 | - | 16.41 | - | 4.41 | - | 12.5 | - | 0.4 |
13 | - | 17.12 | - | 4.12 | - | 13.4 | - | 0.4 |
14 | - | 17.75 | - | 3.75 | - | 14.5 | - | 0.5 |
15 | - | 18.25 | - | 3.25 | - | 15.5 | - | 0.5 |
16 | - | 18.98 | - | 2.98 | - | 16.4 | - | 0.4 |
17 | - | 19.29 | - | 2.29 | - | 17.4 | - | 0.4 |
18 | - | 19.87 | - | 1.87 | - | 18.4 | - | 0.4 |
18.6 | - | 19.9 | - | 1.3 | - | - | - | - |
18.5 | - | - | - | - | - | 18.6 | - | 0.1 |
With the voltage car on my layout (command control) with power coming from a PH-180 through the fixed channel of a TIU the voltage car read about 18.2 volts and the meters were at 18.8 volts. As I understand the TIU, the fixed channels are just straight through, what goes in comes out the same, no chopping or other voltage mods other than adding the DCS signal.
Probably not a very scientific test and I couldn't get the Zcontroller to an even 12 volts on the voltage car. Readings were taken going up only, I didn't check them on the way back down. The Zcontroller was kind of a pain to set at the whole numbers with 0 in the decimal place.
The two TRMS meters I have are both from Radio Shack. One I got a few years ago when it was on sale for like half off, it is a Radio Shack #2200075, TRMS and was around $20-$25 on sale, IIRC. The other one I got when RS was closing their stores around here last year. It was like 70%-80% off and I just could not pass it up. I think it was maybe $15 or so. it's an Extech #EX205T. If the price is right on these things I just can't seem to pass them up whether I need them or not. The go in the drawer with all the Harbor Freight meters I have collected for a couple of bucks or free with purchase.
If you want any specific readings or anything, I will leave all the stuff out for a few days and I would be happy to take any other readings you might want to know about.
Edit: Added voltage car meter range and readings from one of the 'free' Harbor Freight meters I have. Also according to the voltage car the Zcontroller would only go to 18.5 volts today, yesterday 18.6 was it's top reading. The Zcontroller would sometimes move 2-3 tenths and the Harbor Freight meter reading did not change. It also seemed to make a tenth or so difference in the HF meter readings if you were going up or down in voltage from the Zcontroller when trying to get it set to a specific voltage. Again nothing at all scientific here, just fiddling.