I recently purchased a Lionel blinking microwave tower which suggests a power level of 10-14V. I am currently running all accessories including 022s off the center posts on a KW which I believe is 18-20V. If I connect the tower to the accessory block I'm concerned that it will either burn out the bulb or worse melt the plastic housing around the bulb. I suppose I could connect to track power but would prefer to have it lighted with all other lights on the the layout. Is there anything I can do to reduce the voltage to the tower only??
Looking things up in the Greenberg's Repair and Operating Manual, you should be able to use terminals C-D. According to the transformer testing chart on page 679 the output voltage of those two terminals should be 12v. Not having a KW, I can't test it myself, but want to pass this info along as I would hate to see you damage your bulb if you used a higher voltage. The microwave tower is a blinking light like some of the christmas lights. As the bulb heats up, it opens, as it cools it relights.
You have a choice of 6V, 14V, or 20V for the KW fixed voltage terminals, why not run from the 14 volt terminals, that's the C & D terminals. My voltmeter says they're putting out 13.45 VAC open circuit, sounds like a good choice.
Yes, C-D would be the logical choice.
Rob
One note, the C & D terminals do NOT share a common ground with the variable voltage, so the accessories you power from them must be totally isolated, you can't have a common from the track voltage.
My mistake!! I do have all the accessories connected to C & D .... thought that connection was the 18V posts. With respect to GR John's comment, all lighting and 022s are powered off C&D as are 2 other accessories ... a pw 153 and a newer switch tower both of which are activated by insulated rails. Both accessories appear to operating properly ... is this going to cause a problem going forward??
The insulated rails are supplying a ground which is common to the U terminal. That being the case, those accessories are receiving 20 volts if their supply is the D terminal, this is probably not what you want.
Personally, I'd just find a small secondary transformer and use that to power those accessories. The accessory terminals on the KW are somewhat stupidly arranged IMO.
Both accessories are 3 wire, 2 of which are wires to C&D and the 3rd going to the insulated track. Are there any other options using the insulated track?? I suppose track power would work. Thoughts
I'd just get a small accessory transformer, then you can set the voltage to whatever you want. Something like a 1033 will run three or four typical accessories.
Can I use a diode to reduce the voltage?? If I use a different transformer would the insulated rail work??
A diode may be a solution. I assume that those three-wire accessories have something like a light and a solenoid, for example the 151 semaphore. A reasonable way to wire something like this is to connect the accessory common to the fixed accessory voltage, in the case of the KW, terminal D. The accessory's lamp terminal can be connected to C, to get 14 volts. However, the solenoid will get the full 20 volts if it is connected to a control rail, assuming that the KW's U terminal is connected to the outside rails as the layout common.
It would probably work to connect a diode in series with the wire to the control rail. This would reduce the RMS voltage from 20 to 14 volts. This is a little hard on the transformer, since the unbalanced current tends to saturate the iron core; but it's not a whole lot different from what happens when you blow the whistle. Both of these actions are intermittent; so it's likely that no harm will come to the transformer. I suggest a 3-ampere diode, like this one http://www.radioshack.com/product/index.jsp?productId=2062578 .
Bob Nelson
Bob:
Your assumptions are correct .. dealing with a 151 and a 90s version of the 445 switch tower. Two questions ... how do I determine which accessory wire is the common and which terminal powers the light? Also, when you refer to putting the diode in series, are you using more than 1 and which direction should the grey ring on the diode be facing (the insulated rail or the transformer??
For the 151, the center terminal is the common. It is connected to the post and the base; so be careful that the semaphore doesn't touch anything else on the layout since it will be connected to 20 volts. You can find which other terminal goes to the light by experimenting--there are only two possibilities.
The (postwar) 445 is the same with regard to the structure's being common. However, it will be a little harder to figure out which terminal is which. There are terminals on three of the four corners. The one in the middle is for the lamp and will be connected to the KW's C terminal. That again gives us two ways to connect the other two. If you get it wrong, no damage will be done, but the lamp will dim substantially when the control rail is grounded.
There is only one diode per accessory; and it doesn't matter which way it points. If you should be connecting two accessories to the same control rail, it's better to have the two diodes facing in opposite directions.
I'm a little worried by your parentheses, "(the insulated rail or the transformer)". The choice is toward the control rail or toward the accessory terminal for the solenoid, not a transformer terminal.
I misspoke ... you are correct about the rail connection .... it does go to the accessory terminal. Thanks for the guidance ... I'll let you know how I make out.
I tried the diodes on the 151 and the switch tower and the results were varied. The switch tower seemed to hesitate a bit and at times the solenoid got stuck so I removed the diode and the solenoid snaps and releases quickly. With the 151 I saw no difference in the performance although I noticed that I wired one of the wire to the # 2 lockon connection. I may have to change that. Would it be terrible to leave these accessories wired as they are??
Thanks for the post as I am using the KW as an accessory only transformer. Will use a buss strip and go with a lower voltage as that should suffice.
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One problem with diodes for accessories with solenoids, after a bunch of activations the core may get magnetized and cause issues. If you need to drop voltage, a few pairs of back-to-back diodes will drop around .7 volts for each pair but still be running the accessory on AC.
I don't want to say that you can "leave these accessories wired as they are", because I don't really understand how you have them wired. I will say that there should be no problem wiring the accessory common to KW terminal D and the lamp to terminal C, so that the lamp gets 14 volts. You can operate the solenoid on 20 volts by connecting it directly to the control rail, if that's what it needs to work. (I assume that KW terminal U is connected to the layout common, that is, the outside rails generally.)
Your description of the wiring in the first paragraph is accurate for the tower. I have to redo the wiring for the 151 so the light isconnected to C and D. My question is if I wire it with the light to C and D and the solenoid wired to the outer rail (U), will it damage the solenoid over time??
It depends on how hot it gets, which in turn depends on how long it is energized. Something like that might even be damaged if operated continuously on the lowest voltage that it will respond to. You might just check it frequently to see if it is hot to the touch, until you get confidence that the way you're using it doesn't overheat it.
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