Made a DCC amp meter for our club that uses the NCE Power Pro 5 amp system. The PC board with parts was a few dollars. A LED DPM with 0.56 inch high digits for viewing by all in layout room. A LCD DPM with 0.5 inch high digits at the dispatchers panel which is not easily visible to everyone. Rich
Rich could you list where you obtain the parts. Also Since my electronic skills are limited.How would I connect this meter using a SB3A booster and 1156 bulbs. Is a switch necessary to turn the meter on and off ?
I purchased Rob's first PC board two years ago. The upgraded version does not need calibration but being a technician for many years, I like tweaking circuits. I used a 6 amp DC power supply with a couple high wattage, low resistance variable resistors to tweak the DPM's. I had a DPM128 meter in the junk box and set it up for 19.99 volts. The DPM comes with instructions. Do a Google search for DPM128. Many are available surplus and new. It was inconvinient as to why I looked for a LED with larger digits. Do a ebay search for DPM. You will find many larger digits LED type. Be careful, many are sold out of China but I found a USA source for for the same item for about $10.00 by searching ebay carefully. It takes a lot longer to get something from China. I have done that because I found a Sony digital camera media for half the price of USA source with free shipping and the device works very well. No doubt some of you will have different sources and the DPM does not tie up a multimeter. That is another reason to do a calibration. The DPM's have a tweak pot. I always try to at least do some kind of calibration with devices like this. Murphy sometimes can be in the area. When using the clubs NCE 5 amp Power Pro, we see 4.99 amps when there is a short and then zero amps as the system shuts down. Rich
Does this pull any amperage away from your locos? No it does not pull amperage. It drops the voltage a slight amount. Do not confuse voltage with amperage. The PC board is right at the output of the Power Pro. I measure at the track about twenty feet away, about 14 VAC with my DCC voltmeter with a couple locos running. I will have to check the voltage right at the Power Pro terminals out of curiosity. For a test, use ohms law and calculate the voltage drop through the 0.1 ohm resistors. We run as many as eight to ten sound locos with no issues, EXCEPT for shorts. The current is usually around 3 amps at times. Rich
One thing I forgot to mention, some DPM's do not have isolated ground. That means the power for the DPM has a common ground with the voltage being monitored. We do not want that with DCC. I used wall warts for powering the two DPM's. The PM128 LCD requires 9 VDC at about a ma or two so I used a 12 volt, 200ma dc pack with a appropriate resistor to knock down the voltage which was really about 15 vdc to 9vdc. The LED DPM requires 5 vdc so I used a L4931 5 vdc regulator and a couple caps. The only wall wart I could find for this was 7.5 vac at 150ma so I found a full wave bridge rectifier and a cap for filtering which gave me about 11 vdc. I know this all sounds simple but I have been working with electronics at the component level for at least forty years. I have a well equipped junk box. Many times I ripped old electronics items apart and removed different items of interest. Yeah, you might call it dumpster diving. Rich
One more item, the two power packs are plugged into a surge protector device that controls all the mains power for the layout. I mention that because some people have problems with a wall wart that has no power switch. Rich
I have a dumb question here. Can one use this as an adapter for a regular old multimeter set to test amperage?
Multimeter Use the milliamp scale. Follow the instructions in the below link. The link has an upgraded version of the circuit I use. It should require no calibration. I bought my PC board and the two, three terminal devices from this guy about two years ago. http://home.cogeco.ca/~rpaisley4/DCCammeter10.html Then, click on, Return to Main Page for a lot more electronics info. Rich
Thanks for the information. I haven't ruled out using a DPM, certainly, but I thought that for now it might make sense to at least construct the circuit to use as an adapter and then use it for analyzing total power draw. I am thinking about making a "permanent" readout for my home system. This seems a little, err, cheaper than the RRampmeter, and I like fiddling with circuits a bit when I have at least half a clue what I am doing. Cheers, Adam
I have not looked into this upgraded circuit but I think I will. For home use, I have one of the older circuits that I have used for experimenting but have not finalized the install at this time. Rich
Yes it can but the circuit I use requires a little modification for a milli amp meter. Use the upgraded version PC board that uses a milli amp meter instead of a voltmeter. His instructions are very clear. http://home.cogeco.ca/~rpaisley4/DCCammeter10.html Rich Oops, I already answered steam donkey's question. I got there through a link. Rich
Amp meters A DC amp meter measures DC current. A DCC amp meter measures AC current. I can hear the next question. Rich
Ok I’ll play. Would this be the next question “How do you get AC out of DC”? I’m really confused now because my DCC power supply says DC and I thought DCC was DC only modulated. I see this AC thing all the time, but I just assumed it was a mistake.
Sleeper, You are right. DCC uses DC power and alternates between the positive and negative polarity of the voltage. This is not AC. AC has a sine wave . DCC has a square wave. Inobu
The AC you get out of your house wiring is a sine, but AC just means Alternating Current. DCC uses a square wave AC. I think Sleeper is confused by the acronyms DCC and DC which are not related at all. DC = Direct Current DCC = Digital Command Control
Thanks, as a 30 year electrician working on voltages of 120 up to 5K of the real AC power, it just doesn’t set well with me to call it AC.
