Using a Voltmeter (86)

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Күн бұрын

Voltmeters, or more accurately volt, ohm, amp meters are also known as multimeters because of their multiple functions. By any name they can be very useful for work on model railroads be they DC or DCC powered. When it comes to measuring track voltage, circuit continuity, or locomotive stall currents they can't be beat. So come on along while I show you how to make these measurements.

Пікірлер: 28

@SammoKarm 4 жыл бұрын

Well explained, Its amazing how many people assume that they haven't got any voltage, when they are trying to get a reading from the same polarity and not realising they are doing that. I hope a few people will pick up on that point before they look to find, what they think is a problem elsewhere.

@gregorytate7666 4 жыл бұрын

Excellent tutorial on use of a voltmeter for model railroading electrical systems and components.

@ricter591 4 жыл бұрын

Thanks Larry, That was very helpful.

@BALD8BIL 4 жыл бұрын

Thanks for sharing this video and videos like this one

@sparky107107 4 жыл бұрын

thanks for showing how to use that tool.

@TheDCCGuy 4 жыл бұрын

More coming on Monday!

@SammoKarm 4 жыл бұрын

Not criticizing, but it might have been a good idea to explain to those who don't know, how to connect the meter in series with the positive rather than merely mention it. I knew what you meant but some out there are not technically minded or have experience with electricity, some are even frightened of it. Measuring Stall current is a good idea, but if one does'nt have a meter or information as to the expected current, then probably advisable to go for a decoder which can handle the higher currents drawn by older type motors.

@TheDCCGuy 4 жыл бұрын

That’s the value of having access to a collection of old Model Railroader magazines for the NA market, the stall current is usually given in the product reviews. I still like to check and verify since occasionally you get a run with bad motors. One time LifeLike released a batch of Alco PA1 models with incorrectly wound motors that drew 1.5 amps instead of the usual0.5 amp versions. I replaced mine with Mashima can motors. Also the tech support folks will usually ask right off whether you measured the stall current if you call in with a blown decoder. Good point on the wiring issue, I’ll mention that on Monday.

@jhoodfysh 2 жыл бұрын

Thanks Larry for another great video. I have a really, really old (+25 yrs) analog voltmeter and I thought upgrading would be a good idea. I can not find a DM110 from Extech anywhere, nor do the other ones I see have the auto-range feature. Do you have any suggestions or recommendations?

@TheDCCGuy 2 жыл бұрын

The DM110 has been replaced by the DM220 which is cheaper than what I paid for mine. Here is a link to the cheapest price I could find but I have no idea what shipping will be so Amazon may actually be less. www.testequipmentdepot.com/extech/multimeters/pocket-digital-multimeters/mini-pocket-autoranging-digital-multimeter-600vac-dc-200aac-dc-ncv-detector-dm220.htm?ref=gbase&gclid=Cj0KCQiAgP6PBhDmARIsAPWMq6mhXW-Tt5jRmKsqiq703k0TWnDIxbVGPdQ05uKGDrwnyFeM5sRoxjIaAm9OEALw_wcB

@PB-fw2mx 4 жыл бұрын

Hi Larry, thank you for the informative video. I have a few older non-dcc locos that I would like to install a decoder. How can I use a voltmeter to check if the motor is isolated from the frame. A continuity check, I assume?

@TheDCCGuy 4 жыл бұрын

A continuity check is what you need to do. Some brass locos use a metal screw holding the motor in place to the chassis as one leg of the electrical pathway. Same goes for Atlas S2 switchers.

@PB-fw2mx 4 жыл бұрын

The DCC Guy. I know Athearn blue box locos are not isolated. But specifically, how do I check in any type of loco. Do I put one prong on the frame and where would the other one go? Where on the motor?

@TheDCCGuy 4 жыл бұрын

Yes, one on the frame and the other on the motor case or any exposed metal parts that could be in contact with the frame. Also look for any wires going from the frame to one motor contact. Most Athearn ready to roll locos, some Atlas switchers, old LifeLike and early Walthers models tied a motor contact to the frame. I will be doing an install this week and show an Athearn loco with a frame contact. Most of the time you can easily see a motor to frame contact without even having to use a meter.

@SammoKarm 4 жыл бұрын

I assume you'll be talking Oscilloscope's, I'm interested to see which one you recommend. Not sure if you will be talking single or dual channel though, My old Oscilloscope gave up the ghost about 15 years ago and I haven't bothered to renew it yet, but will be interested to see if you can give me a reason for replacing it. Thanks.

@TheDCCGuy 4 жыл бұрын

Nothing that sophisticated, plus I just got a notice fro DCC Concepts about a new product they just released that I’ll mention.

@HumancityJunction 4 жыл бұрын

I have an older Fluke 83 that works really well for MRR but my mid level Extech does not work.

@TheDCCGuy 4 жыл бұрын

As a rule Fluke makes excellent meters. I have been using Extech equipment for years too with excellent results for scientific research. They apparently produce a range of meters from the consumer product level to much more advanced. The one I have is a mid-level meter that can do volts, resistance, and low range amperage measurements but as I mentioned it cannot measure amps above 400 milliamps, which turned out to be a limitation for me. Most folks will probably never use a multimeter for anything more than standard voltage and resistance measurements and if you need a stall current Model Railroader regularly provides those in their product reviews. My warning though is to steer clear of the cheap meters you find on Amazon, eBay, and other vendors just like I warn against the cheap soldering irons.

@HumancityJunction 4 жыл бұрын

@@TheDCCGuy Am I correct that you like the Hakko FX88D FX-888 over the Weller 1010NA? I need to get a good soldering iron and I cannot decide between these two.

@TheDCCGuy 4 жыл бұрын

I did not look at the Weller 1010NA when I bought the Hakko a year or so ago. I will admit I was a bit turned off on Weller as a result of the grounding problem with the Weller WLC100 station and the Hakko came up with good reviews on that issue. It is a bit clunky as far as changing the tip temperature setting but you get used to it after a while. Here is a head to head comparison of these two meters so see what you think. I have not had time to watch the video yet myself. kzfaq.info/get/bejne/qtJ7mpmjuLO0dac.html

@SammoKarm 4 жыл бұрын

Not related to this but I'm interested to know. Do you still use loco's with the straight wound rotor, motor, or do you change the motor for skew wound. I no longer use loco's that don't have a skew wound motor cos I occasionally got a loco which wouldn't start because non of the poles were energized, so I had to crawl under the layout to get to the offending loco or send another loco out to give it a nudge.

@TheDCCGuy 4 жыл бұрын

I do prefer the skew wound motors as they perform so much better. The loco I showed is a spare for parts that I had laying around. I also have a couple of brass models that I have replaced the old open frame motors.

@SammoKarm 4 жыл бұрын

In the UK we run at 50 hz. Not relevant I know but just thought I would mention it.

@TheDCCGuy 4 жыл бұрын

Most of these meters are designed for 50-60 Hz so should not be an issue.

@farmerdave7965 4 жыл бұрын

Don't buy that really cheap multimeter from harbor freight. The response time is really slow. I grew a beard while waiting for a reading to appear on the display.

@TheDCCGuy 4 жыл бұрын

Jameco.com is a good source and I think I got the one I used fro them. Amazon is a good source too, just be careful when ordering knockoffs from China, etc.