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DCC Track Voltage
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This question is probably like asking how long is a piece of string!
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What is the optimum/maximum voltage for operating DCC and how do you measure it? I am running a NCE system and at small load (0.35 Amps) the SB5 output I have 16.5 V using the RRAmpmeter and 17,7 V using my Snap On multimeter.?
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What are the constraints/considerations?
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Thanks
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Len |
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Hi Len,
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You want your HO track voltage to be about 14 - 14.4V.
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Definitely use an RRampmeter to measure the track voltage.? DCC voltages usually cannot be read accurately with a meter that was not specifically designed with DCC in mind.
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Also measure it with a load on the track.? If you measure it without a load, it will read higher.? I'm guessing you got 16.5V with no load on your booster or not much of one.
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The manufacturer of your decoder in your locomotive will tell you the maximum track voltage it take without damage.? Sometimes this can be over 20V.? Since you are reading under 19V, go ahead and use a locomotive as a load to measure your booster voltage.? HO decoders can take take this at least long enough for you to make a measurement.
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Besides the obvious that the decoder's electronics cannot take "high" voltages, higher voltages can overheat decoders.? So if you are getting 16.5V with a locomotive load, review your SB5 documentation and see if it can be dialed down a bit.
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Allan Gartner
Wiring for DCC |
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While a RRAmpmeter is a great tool, I find a digital multimeter much more useful.? However, you need to make sure it reads true RMS voltage and has a high enough frequency response to work with DCC signals.? What I've been using is a OWON B41T+ meter that I bought from Amazon for about $80.? Had it for several years now and it is definitely worh the price.? It gives me accurate DCC reading but does much more in working on layout and electronics in general.? Most general purpose multimeters, even Fluke, don't have the frequency response to work with DCC.? I have 4 different multimeters that I've bought over the years and the OWON is the only one that works for DCC.
Good Luck, John Moonan |
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That's been the discussion for ages. Is a RRampMeter necessary? If you can afford it, by all means, buy one.
But if that meter sounds expensive, then the HF meter or 2 or 3 are going to be sufficient.
As for 15v, that's the ideal. But 14.4v or 14.7v is not going to hurt anything.
And when I measure volts, whether with the HF or a TRMS meter, if the track measures 14.4v anywhere up to 15v - that's all I need to know. The world won't come to an end if it's not 15v at every place I measure.
Any difference can be attributed to the variance in the meters.
Morgan Bilbo, DCC since 8/18. Model PRR 1952. |
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This is an interesting thread. For a large layout such as the Amarillo Railroad Museum, we have found the panel-mounted Ramp Meter to be very useful. We have eight power supplies (by that I mean the DCS and DBs). Each one has a separate Ramp Meter, so the track voltage and amperage can be monitored for the whole layout. I realize that this would be overkill for a small to medium-sized layout. The amperage output is the most important feature for us. During open houses, members tend to get too many locomotives in one power district. If there is a derailment, it is often not possible to get trains running again because the in-rush current for sound decoders. Most of our members don't know much about electronics, and don't understand that the system can be overwhelmed. Monitoring power consumption has cut down on this problem, and of course the meters are great for troubleshooting. Jerry Michels
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JerryM: You verify what I'm saying. That a large club that has the financial resources can afford the RRampMeters, that's the thing to do.
And I repeat that the RRampMeter is a great tool. 'IF you can afford it'.
For those like me, are frugal, and don't 'need' that accuracy, the normal TRMS is an acceptable alternative. Not as accurate. But is more feasible.
Morgan Bilbo, DCC since 8/18. Model PRR 1952. |
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Regards, Theo --? ? ? ? ? ? ? ? ? Greetings from the heath in the north of Belgium? |
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TheoVR: I thought I had disclosed that I do not own a RRampMeter. They are too expensive. What I am saying though - is - that for a club or large layout - they usually have enough money to buy what they need, be it one RRampMeter or more. And for them, that is a good purchase.
Since I don't own one, I can't say what they can do best, just that it's known they are more accurate than a regular multimeter.
What I do have and use is 2 HF el cheapos and 2 higher quality TRMS meters. These are more than I need. And probably about what any modeler can want/need. The HF's are free or $7. The other meters I own are $25 and $30. And JoeF's article in MRH mentions several others that are cheaper.
And all I can honestly say for sure. Is that I have found my 4 meters to be more than sufficient for my needs.
And would probably be the same for a majority of modelers. Especially if you think $80+ (I don't have exact cost, but I recall they can go to $100) is too much for the RRampMeter.
Again, the only thing that is commonly mentioned is that the differences are in accuracy.
And back to personal use. When I measure my track. And the meters show anywhere from 14.5v to 15v, I am satisfied. I don't need the accuracy that tells me I have 14.999v.
OTOH. The RRampMeter does give amps. And there aren't any multimeters that can measure amps for DCC. And that is something not easy to measure.
Morgan Bilbo, DCC since 8/18. Model PRR 1952. |
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I don't want to belabor the point. But I am finding RampMeters run in the $100-$130 range. That doesn't seem excessive when a DCC/Sound locomotive costs $250-$400. It is priorities. Do you prefer to add the 30th locomotive to your railroad or buy a precision device that measures power, especially amps? I mention this because a lot of posts make the RampMeter sound terribly expensive when I don't believe it is the case. I agree that buying a lot of RampMeters can get expensive, but for the small layout, one RampMeter tied into a rotary switch would allow a person to monitor many power districts. Jerry Michels
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No problem Morgan, my question was not personal, just curious.. What kind of problem needs a RRampMeter to solve? Theo DCC since 2008 and computer controlled traffic . |
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***THX Jerry !?? I only have one meter, never thought of the rotary switch to check more districts ! Bill*-*
On Sunday, February 9, 2025 at 10:02:06 AM EST, Jerry Michels via groups.io <gjmichels53@...> wrote:
I don't want to belabor the point.? But I am finding RampMeters run in the $100-$130 range.? That doesn't seem excessive when a DCC/Sound locomotive costs $250-$400.? It is priorities.? Do you prefer to add the 30th locomotive to your railroad or buy a precision device that measures power, especially amps?? I mention this because a lot of posts make the RampMeter sound terribly expensive when I don't believe it is the case. I agree that buying a lot of RampMeters can get expensive, but for the small layout, one RampMeter tied into a rotary switch would allow a person to monitor many power districts. Jerry Michels |
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What are club has found to be very useful but a lot less expensive then a RRampmeter is an inexpensive combo DC volt/amp meter installed between the DC power supply for the booster and the booster power input connections.? We use a meter like "HiLetgo 0.28" Digital Voltmeter Ammeter" that we bought on Amazon for $5 each.? They show the input voltage and current for the booster and these track very closely to the booster output.? In particular, the input current is almost exactly what the track current is as the booster itself has an insignificant current useage.? These allows us to look at the load on each booster which is exactly what the RRampmeter does and for a lot less money.? We've had these installed for a couple of years now and they have proven reliable.
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Good Luck, John Moonan
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I'd say, don't overthink this! DCC is made to be unfussy! If there is a little variation in voltage from block to block and booster to booster, decoders with back EMF will compensate and your loco speeds should be almost constant. It's unlikely you'll notice any effect. My EasyDCC boosters, and I suspect many or most others, use low resistance MOSFET switches to alternate the rail polarities to convert the DC from their external power supplies to the track DCC. The track voltages will usually be only a tenth or so of a volt lower than the DC into the boosters. Setting the DC power supplies to approximately 15V is close enough. If you have any current sensing diodes or resistors in the wiring between the boosters and the rails, they will reduce that voltage a bit, but your decoders and equipment should run just fine. And, the power supplies' DC voltages to the boosters are easily measured, with no need to worry about meter frequency response. Similarly, the DC input current to the boosters should be just a little bit more than the DCC current to the tracks. A little bit is needed internally to power the boosters' circuits, but not a lot compared to boosters' track current ratings.?Again, no fancy meter is needed to measure DC Amperes into the boosters. Don -- Don Weigt Connecticut |
开云体育I get my old” gauges” at ham fests.? They have a zillion of meters.? Just google “hamfests”.? They are all over the country. Some are small and some are quite large. I’m going to one in Dayton, Ohio in May.? Other large ones that I know about are in Orlando and Huntsville, Alabama. They are big flea market of just electronic stuff and have lots of old meters.? You can get them for just a few bucks. ? Analog meters can be gotten in AC or DC, can read volts or amps, and come in all sorts of ranges. ? That said, analog meters cannot to read DCC voltages and current (amperage).? You can read the voltages and current going into your booster; just not those coming out.? If you have electronics talent, you can probably develop circuits that would allow them to read DCC voltages and current.? You will probably have a challenging time finding an analog meter that reads your desired range.? For example, you may have a hard time finding a meter that displays 5A, AC.? You may find a 100mA, DC amp that you may need to design a circuit to read DCC amps. ? I have two old meters that I use to read DC amps.? They were probably made before I was born.? They do look retro! ? Enjoy! ? Allan Gartner ? From: w4dccqa@groups.io <w4dccqa@groups.io>
On Behalf Of Greg Harter via groups.io
Sent: Tuesday, February 11, 2025 8:05 AM To: w4dccqa@groups.io Subject: Re: [w4dccqa] DCC Track Voltage ? Not really off subject.? Where might one get a couple of very old gauges? |
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