norcalmodelerthanks, this is the answer i was looking for. but, you said AC amp meter. wouldnt it be DC. doesn't the power supply convert to DC before it goes into the booster?
CSX Robertnorcalmodelerthanks, this is the answer i was looking for. but, you said AC amp meter. wouldnt it be DC. doesn't the power supply convert to DC before it goes into the booster? You have to match the ammeter to the power supply. The booster will run off of a DC or an AC supply.
Yeah, I keep forgetting some DCC controllers/boosters have a full wave bridge rectifier inside so the devices can be powered by just a AC transformer or a DC power supply. Then you can use a standard AC amp meter or DC amp meter.
The cheap multimeters can have a 10 amp or 20 amp max scale. MIne have 10 amp max scales.
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.
Unfortunately, I don't have a DCC system here on which to test this, so it is just a suggestion.
Cut a break in one of your DCC power lines and connect the two wires to the AC inputs of a full-wave rectifier. Then connect the DC outputs of the rectifier to a DC ammeter. I'm thinking that an old fashioned analog ammeter will work better than a digital one because of the effects of sampling in the digital one, as noted in one of the above posts.
The rating of the rectifier should be about 50 watts because the total voltage drop across it will be about 1.5 volts and your power supply has a capacity of 20 amps. Maximum power dissipated in the rectifier will be about 1.5 X 20 = 30 watts. I recommend 50 watts for the rectifier to include a margin of safety.
I'm figuring that, no matter which way the electricity is flowing in the DCC power line, the rectifier will direct it through the ammeter in the same, correct direction.
Two questions that testing may answer:
Will the rectifier work well at the high frequencies that DCC uses?
Will the high-speed rectification cause unacceptable electrical noise?
Below is a link to a DCC amp meter I installed for less than a Ramp meter since I lie to work at the component level. I am using the voltmeter option.
http://cs.trains.com/trccs/forums/p/173404/1902749.aspx#1902749
The fellow I bought the parts from has a simpler one that uses the 20ma scale of a cheap digital multimeter. I have three of that style meter and they are very close to an expensive meter. Rivet counters will tell you to use an expensive meter. If you misuse a meter, guess which one is a less costly mixtake.
His site has facts, not opinions about measuring DCC current.
Below is a link to his site with different options. The is a link for the device that actually samples the DCC current. Read everything. Don't assume.
http://home.cogeco.ca/~rpaisley4/DCCammeter10.html
Hmm, if I was more ambitious, or just wanted to make my layout look like a power plant control center, I'd get 4 of Rob's circuits and use the guts out of 4 of the $2.99 Harbor Freight specials and just mount them behind the fascia, with a little cutout for the display. More than adequate and plenty accurate. And cheap.
I'll have to pull the back off one of my meters and check - I bet the guts could be trimmed back enough to make a portable version that has Rob's circuit inside the case. A little careful rewiring of the probe sockets, or just putting in some other connections that run to clip leads and you'd have a handheld portable DCC ammeter.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.