If I were going to use a HF meter in a permanent installation, I'd take it out of the case, for one thing. Probbaly remove the range switch and hard wire it to what I needed. Remove the probe sockets as well. And power it from a power supply, not use a battery.
Considering a new battery often costs more than the meter (at least the models that use the coin cell batteries), they truly are disposable. I have yet to have any of the half dozen or so I have laying around experience any physical fault though. Note that these things are not protected in any way and should only be used with low voltage (20 volts or so). The 10 amp range is not even fused, unless you count melting the meter and/or the probe wires as a 'fuse'.
What they are though, is surprisingly accurate compared against reference standards.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Forgot to mention, I have four of these meters and made my own longer probes with soldered connections. I keep one in the car. Twelve volt system.
Easy to misplace one in my mess and cheap to replace if damaged which has not happened yet.
Few years ago I bought the replacement fuses from Radio Shack for the meter.
They compare very well to an expensive meter.
I have used multi-meters since 1954 and have no trouble using these meters. I understand the possible limitations.
When I first tried a meter, I realized DCC might be a different reading so I probed right at the booster output. I used that value as a benchmark. Probing down the track and a lower voltage would tell me a feeder, track connection issue. Since the DC power to the booster was about 14vdc, I knew I was ok with the AC readings. Measuring about 12vdc for the decoder output for lighting in my decoder tester told me every thing was ok. Yes, I know, not everyone wants to do that.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Re: the Harbor Freight meters, it would be my opinion that a better meter should be purchased for any semi-permanent installation.
I had one that stopped working because the connection socket for one of the leads failed.
I had two where one of the lead wires slid out from the probe. There was no evidence of any solder or any other method of how the lead was actually connected to the probe. This condition appears to be non-repairable other than splicing an alligator clip to the end of the lead. And it is most frustrating to have this happen after one has dragged a work light, soldering iron, and other tools under one of the remote locations of the club layout.
Since HF periodically "gives" these away free with any purchase, I have a hard time believing that much quality is built in during manufacturing.
The HF meters are probably MORE accurate reading DCC voltage than some slightly fancier ones - because it DOESN'T do RMS. A plain RMS meter is calibrated for sine wave AC, and will give the incorrect result with square wave signals like DCC. A meter claiming True RMS typically can handle multiple ave forms like sine, square, and triangle and give an accurate result - up to some specified frequency. Not all do audio range and beyond, and most tend to get less accurate the closer you get to the maximum frequency (although depending on the meter, "less accurate" can still be in the millivolts).
Other than the cool factor of having a bank of meters showing voltage and current, it's probbaly more important to monitor current than it is voltage. Voltage can be tested with a handheld meter to make sure all districts have the same voltage, any drop enough to worry about will be noticeable as slowdowns and/or increases in current. Since I have no intention (nor is it really a good idea - at least when talking about a larger layout that actually needs multiple boosters) of clustering all my boosters in one spot, I'd end up with meters all over, not in one nice power control panel. Running long bus wires all over the place just to centralize the boosters defeats half the purpose of having multiple boosters to distribute the load and keep bus runs short for less voltage drop.
Good stuff, Randy and Rich.
Alton Junction
My Harbor Freight digital meters read 13.6 vac with my NCE Power Cab.
The club layout uses a five amp Power Pro and we measure about 13.6 vac.
Both readings could be plus or minus 0.1 volts. Readings can depend on resistance at track joints, where the buss wires connect to the booster, junction points under the layout.
A load is needed such as a loco for proper trouble shooting or you generaly will not see a high resistance junction.
I built two DCC amp meters using the link Randy posted. Cheap enough for a DCC amp meter. I bought a two inch high digital meter and connected it so we can see the current reading anywhere in the club. It monitors where the booster connects to the layout. I used his first circuit maybe eight years ago which is the voltmeter version, not the version using a HF meter on amps. scale.
I have a heavy duty rheostat, called a high amperage potentiometer by some, I clip across the rails as subsitute for a loco and lower the resistance. The power pro trips at about 4.95 amps.
I have a Scope to compare readings also. On big layouts, spiking can occur which the HF meters will not show.
Most of those mini panel meters for cheap are DC volts and/or DC amps, so they aren't too useful for DCC.
Rob Paisley has a circuit that does pretty much the same as the RRAmpmeter: http://home.cogeco.ca/~rpaisley4/DCCammeter10.html COmbine that with those cheap panel meters for the readout and you have the same sort of thing for a whopping $15 - $20 (If you get the fully assembled board from Rob with terminals, they are $12 each.). Most of the voltmeters are adjustable, so you could claibrate it to match the RRAMpmeter which would give you a close enough reading.
Hello Gentlemen,
I have been following cs.trains for quite awhile now because it seems to be the best forum for great, knowledgable people. This is my first post and if I am in the wrong spot, I ask the Moderator to direct me to the correct thread.
I have been into Digitrax DCC for over 15 years now and dont think Im any smarter yet....lol. I have 5 power districts on the layout with 4- DB150s and 1- DCS100 Booster/Command. Having been a Supervisor of heavy equipment for 30 years, I love my gauges to tell me what is going on with whatever is running. I have a RRampmeter that is a bonus to any layout but they are fairly pricey for what I want to do. I am running over 20 BLI AC 6000s with sound and all are MU's and on occasion, some will cross into the same district where I think a booster is getting overloaded with too many locos in that district. I also have some steep grades in the layout too.
My question is, I would like to monitor all my districts (boosters) for track voltage and especially amp draw individually, so Id like to make a panel to house 5 digital meters. To do this with RRampmeters will be pretty costly compared to some of the combo digital meters I see online.
Does anyone have any experience or advice on good quality, affordable digital meters that would do the trick? A lot of what I am finding online so far are either DC or if they are AC, they start at a lot higher volt/amp range than what the DCC system operates on.
Thanks for reading my post and I am looking forward to learning more from all the MRR's on this site.
Jim