I have seen mention several times about running at 12 volts. Will harm come to any engines, etc. if my voltmeter shows higher?
Foth, The DC motors are built to run at the voltage stated on the box they come in, we all know that. I have used DC for many years in the security business to power camera domes and the like. The motors we used before they went to low voltage AC were good only 2 volts above or below the recommended voltage. If there was any more or less that 2 volts the motor would die before its time. High or low voltage to any motor is always fatal sooner or later. My advice is if you are running at 12 volts and your meter says something over 14 volts or under 10 volts, fix what ever is causing the high or low voltage. Your motors will love you for it and last a lot longer. Shannon WP LIVES ATSF LIVES
Mark, I think I'll follow Mark Twain's observation about why we should listen to children: "They tell what they know, and then stop." In other words, I ain't no EE. Here's what I know: Some motors will tolerate an over-voltage condition. Mabuchi-FFs--a cheap motor that many use to repower steam locos--are rated at 6.3 volts, but seem to do very well in our 12-volt world. Many other motors will fry at that level of over-voltage. We rarely run at maximum voltage, unless we winding up to use our trains as wallboard penetrators. Even on DCC. 20.4 volts will fry most lamps and LEDs quickly, especially DCC. Things ran better when I turned my DCC system down from 14.3 to 11.4 volts. Stop.
Mark: I run my DCC system at 13 volts and am considering dropping it to 11.5 volts. 20.4 volts would fry every loco on the JJJ&E. Stay cool and run steam....
When I do my line tests with a voltmeter and the power is all the way up, it is 20.4. The trains certainly don't run at that speed. With my trackwork, it is an absolute certainty they will not stay on the tracks long enough, in any event. However- to be safe- is there a special thigamagig that can be attached to the transformers to be able to set a maximum voltage? If so, what might it be called?
Mark, I think you're running DCC, correct? (I'm having a real brain fade today, sorry.) If you're running DCC, your voltmeter may be giving you a false reading from the track. I think you need something like the voltmeter from Tony's Train Exchange, something that measures RMS voltage, or some such. Maybe someone else can clarify, as it's been as least 20 years since Ohm's Law passed through my brain, and then disappeared. I think you need to measure your voltage at a different point in your system, before the DCC component is added. I think the DCC component multiples voltage by a factor of about 1.5 on an ordinary DC voltmeter, so you may have about 14.3 volts actual, which is the nomimal HO voltage. My DCC system manual showed my how to turn the voltage down. Maybe if we moved this to the DCC & Electronics Forum we'd get a better answer? I'm a real newbie to DCC, so don't expect my answers to conform to Ohm's Law. I get easily confused these days about things electronic. [ 10. December 2004, 20:45: Message edited by: Pete Nolan ]
Your pack may be putting out a square wave with AC ringing. You have to measure the voltage with a load (train) across the tracks. If you look at transformers, they are listed at 13.5V, which is 12V with a load across the outputs. Motor control circuits are not so finiky as electronics, which is why a good regulated power supply costs more than a train trainsformer. That also means you don't want to power LEDs and such from your power pack unless you put in a regulator circuit. I get a power supply from Radio Shack for electronic accessories, and use the power pack aux for switch machines (motors). I run all my trains at either 12V or 0 V, no slacking off around here! (PWM throttle) Tony Burzio San Diego, CA
Pete- Me? DCC? Figuring out DC was hard enough for this boy. Tony- I am running DC and have four MDC 260 power units. Does this clarify?
Some information from an EE...... DC motors do not like to see above-rated voltage on them. That said, on a DC system just because a power supply CAN put that kind of volvtage out, doesn't mean you'll ever use it. As long as the maximum operating voltage doesn't go above that level WITH the locomotive running under load on it, you'll be O.K. Many power supplies put out quite high voltages until they're loaded down. On a DCC system, a lot of people put 14 volts on their system. You can limit the voltage to the motor by programming the decoder with different operating parameters (slower top speed) to limit the actual voltage to the motor. You've got to look at the voltage across the motor terminals with the engine running under load to see what the voltage actually is. This is obviously harder to do. As has been said, many cheaper voltmeters get freaked out by the DCC square wave that's on the tracks. You need a true-RMS reading meter to see it. Mark in Utah
Ah, yes, RMS--root mean square--not REM, the rock band. Brain has shut down--probably from low voltage.
The RRampmeter that Tony's sells give an accurate voltage and amp reading on your layout. I check my track voltage all the time with the RRampmeter. You can use for DC as well as DCC. Tony's RRampmeter Stay cool and run steam.....
Hmm, maybe you are not getting enough REMs, (Rapid Eye Movements). or sunlight. Half serious here / half silly
Believe it or not, GG, we've been through a few weeks where I would swear I was in New England. Gray, cloudy, windy, snowy--though today was fine!
Mark, Remember DCC is square wave AC not DC. So to that end your VOM should be on the AC side of the meter. Save yourself some money and by a good VOM. It will never fail you and with proper care will probally last much lomger than some of the junk on the market passed off as DCC meters. I am an EE and what I told you at the outset of this thread is still true. Don't over volt ANY motor. If you do don't expect much life from it. I try to keep this stuff as simple as possible because I do not know anyone's skill level. If you always use the KISS principle (Keep it simple stupid) you will not loose the people you are trying to help. Now I will get off my soap box. Shannon WP LIVES ATSF LIVES
Shannon- "Remember DCC is square wave AC not DC. So to that end your VOM should be on the AC side of the meter" KISS- For me it is KIRS - Keep it really simple since I am really stupid. Last night, I wired up a reverse loop to an Atlas Controller and it worked first time. I was as happy as a pupply in a shoe closet. Last night, I ran a few trains really fast and attached my voltmeter to the tracks. It registered 10.something. They will never go above that. Although I know that I should understand the "basics" of electricity, I am still trying to understand the basics of the laws of the State of New York, and I have been at THAT for 30 years. Please, just point me in the direction of a device that will cap the voltage going to the tracks at a preset number determined by me. I thank you for the explanations and time.
Mark, OK, let start from the top with electrical stuff. When I was taught about electricty at the ripe age of 7 my dad explained it to me like this. There is a plus (Red) and minus (Black) in electrical operated stuff. Think of this as hot and cold water lines. The point is to NEVER cross them. You can apply the same theory to AC and DC. Smooth wave AC is like your house current. If you put a scope on a plug in your house it would look kinda smooth. But because of the way is delivered to you via the power company it is not truly smooth. OK I am getting of the subjet here. With AC the black can be and normally is the hot leg. The white is the common. In the case of DCC power the AC is delivered to the track in low voltage instead of 120 Volts. When you look at this with a scope the power wave is kinda square. So it is called square wave AC. If you are trying to limit the voltage there are two ways of doing this. I think someone makes a current limiting circut board for DCC but I do not know who it might be. I think one of the other people in the thread showed smoething like that. You may want to check back into the thread and see. I you can't find that or it is to expensive, the old fasion tried and true method is a device called a pot. We use them to control sound in our radios, scanners and the like. Find yourself a good electronics store and tell them what you need. Make sure it is low voltage rated, and make sure you tell the sales guy the voltage you are useing. The effect is once it is hooked up (and they are very simple to hook up) you will be able to control the voltage in any area of your layout where the pot is wired in. Also, take all of your engines off the track and turn the power on full and see what it reads. Thats the best way to find the true power out put. Give that a try and let me know how it works. Shannon WP LIVES ATSF LIVES
