Hi Engine 304
I based my comments and concerns on the K-D #309 install instructions Fig-Y that shows an 18v ac input to the bridge rectifier. If memory serves, that will give a max DC voltage of about 1.4 times that after the bridge rectifier, or in the neighbourhood of 25v DC. This may be less under load if the input supply sags or you do not use the capacitor. That's why I was wondering about heating... however, 2 minutes seems a long time to do an uncouple. Even I should be able to do it in that time. Another reason for the paired 12v DC approach is that I have a monster computer supply that gives about 12vDC @12A. I only trip the breaker if I have more than 7 uncoupling stations active at a time (I use relays to energize groups in the yards,, saves real estate on the control panels.) My supply is rather inefficient, and was hoping to retire it, but think it will be in service for some time.
Having fun....... George
Dr. Frankendiesel aka Scott Running BearSpace Mouse for president!15 year veteran fire fighterCollector of Apple //e'sRunning Bear EnterprisesHistory Channel Club life member.beatus homo qui invenit sapientiam
Wal-Mart's craft section carries several kinds of magnets. I've had success with the strip magnets and lately tried some disc magnets. The discs are more powerful than the strip but they are a little smaller than a dime. You need two side by side. The drawback here is that you have a short distance in which to get uncoupled. They are for undeer the ties, side by side, not long ways.
The strip magnets need to be stacked one on the other. Make the top one a little shorter than the bottom. They will be used on top of the ties.
Both are VERY cheap! They both work well for me.
_______________
Walter
Hello George,
Kadee's "new" #309 uncoupler should not be operated on more than 16V DC (18V AC), and the coil should not be energized continuously longer than 2 minutes. Also, the unit needs 3Amps, so a small power pack may not do. You can find this info on Kadee's website: click on Product Info, then on instructions, then under HO Scale you will find #309.
I have tried different DC-voltages on an "old" 309, it seems that the magnetic field strength drops dramatically on lowering the voltage, so one should use as close to 16V as possible.
Have Fun, Wolfgang
I have used similar magnets for about a year and a half now. (3/8" diameter x 1/8" thick). They go under the ties. Once ballasted they too are virtually invisible. I have one spot where the main comes down a 1% slope on a turn. Twice in this time I had an unwanted uncoupling when the engine stuttered on a piece of crud on the tracks.
On the entire main line there are ten places with these magnets. No other has been any problem. It's hard to say how many runs past them the trains have made but 100 a week is probably a safe guess. 100/week * 78 weeks = 7800 runs past ten sets of magnets with two unwanted uncouplings. About 0.0025% failure rate. I can live with that
"Don't fear the magnets"
Uncoupling on purpose does require a bit of careful throttle work because positioning is critical. You get used to it and you can always place two sets next to each other.
Karl
The mind is like a parachute. It works better when it's open. www.stremy.net
KKEIFE wrote: Loathar: Do you ever have problems with cars uncoupling when you don't want them to, as in when the cars are just passing by the magnets?Do you mount two of them, one next to each rail?
Loathar:
Do you ever have problems with cars uncoupling when you don't want them to, as in when the cars are just passing by the magnets?
Do you mount two of them, one next to each rail?
Andy Sperandeo MODEL RAILROADER Magazine
http://gmcrail.freeweb7.com/Here's another option that's a lot cheaper. This is gmcrails web site. Scroll down to last picture of the first page. I've been playing around with this idea and it works really well. It's a heck of a lot cheaper than the KD's or McH's. This is where to get the magnets at. They're unbelievably strong! And you can't even see them.http://www.kjmagnetics.com/products.asp?cat=13
I am using pairs of Kaydee electromagnet uncouplers in each location. In my configuration they work well, and are completely below the ties on the track (HO scale). The reason I use them in pairs is to increase the magnetic strength, as I only feed them 12v DC, wired in parallel. I put the 2 coils side by side together and use all 4 of the pole pieces, 2 on each side with the folded-in tops of each pair facing inward. The newer, improved? units come with some semiconductors and plastic bits that may get used somewhere, but are not useful right now. The central bolt must be replaced with a longer one as it holds all the pole pieces and the 2 coils together along with home made aluminum brackets that are screwed to the bottom of the roadbed. The only adjustment is to get the pole pieces to be as close to the bottom of the ties as possible. Cover the hole in the roadbed with a piece of computer card (remember them?) and the ballast will in turn hide that too. They are a bit pricy in pairs, but work well on just about any of the worst of my couplers. Being pushbutton-controlled electromagnets means I can park a train over one and not have to worry about leaving something behind when it is restarted. Use permanent mags only on spurs.
Have fun..... George
Any one compared the McHenry vs Kadee under track couplers?
I need to place some on the far side of the layout and only use in frequently so I'm wonder if McHenry's are as good as Kadee's. Only differrence I see is they don't come with a steel plate but they are way cheaper. And are they about the same size?
Don't need all the reasons why the hand is better, thanks.