Resistor voltage drop is proportional to the current flowing through it, seems these new motors don;t draw enough current to get enough of a drop, until you get the reistor so big it drops too much. A silicon diode drops .7v from almost no to max current draw (well, close enough for our purposes) so the load doesn;t matter, .7V less comes out.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Well, if they bounce too hard, then the contact through the switches is working ok. Some of the bigger pushbuttons at Radio Shack are better wuality, or you could look at the myriad of shapes and sizes from some place like Mouser or Digi-Key.
Hmm, no resitor, too ahrd, even low resistance like 15 ohms, not enough. I wonder if something like a high current diode would work, drop the voltage by about .7 volt. Look for the 4 amp or so ones at Radio Shack. If it's backwards, nothing will happen, so you have to hook it up in the right direction, Just for the problem turnout.
His last reply corrected it to proper #18.
Do they work 1 at a time with the CDU, or the same bouncing? Do they not throw, or do they actually throw too hard and bounce back, I guess that is the question. You mentioned the Atlas ones 'mostly' work with the CDU - they should definitely work reliably, that's what I used, Atlas N turnouts and the quick recharge CDU circuit from Thorne's book. They always worked - although I did have individual controls for each one, not one pushbutton and a rotary switch. Either of those could be the source of trouble, burned contacts on one or the other switches, and if they pushbutton is one of those little red button ones from Radio Shack - I ALWAYS had trouble with those, with poor contact, even when new.
The switches are probably the easiest to bypass and check, if the turnouts operate reliably with touching wires, then you need new switches, if not, it could be the CDU, if you built it as long ago as I built mine, the capacitor may be dried up and failing.
Question about the "#8 wire" you say you used. #8 wire is about 1/4' in dia. Are you sure of the wire size?
8 gauge wire wire is definitely overkill for this. #18 is more thsn sufficient when powered through a CD unit. Even smaller, with N scale switches, really. I think my N scale layout has #20 wire.
It's possible they are burned out, or at least partially burned, which would account for erratic operation. They should reliably throw in either direction, especially one at a time touching the wires to the CD supply.
Hi Randy thanks for the follow up...
I think I meant parallel. It's hard to know based on how I did my switch wireing. My deceased Dad built the control panel. I have two colored wires I think are connected to the control panel throw buttons going to 2 8 gauge bus wires running the lenth of the railroad. Then I have a common black wire going to the common terminal on each switch. On the two turnouts in question the black wire comes out and splits with one line going to the switch at right end of the siding and the other going to the left. Colored wires from these switches are just droped down and soldered to the bus wires at the closest point.
I have tried disconnecting each switch and operated each with a variety of resistors and found the switches are not matched well. The one on the right seems to operate best with a 10 and 15 ohm resistors in series and the other switch works best with just a 10 ohm resistor. Either way the switch motors are not reliable 100 % of the time. Sometimes It seems like they only have 1 coil!
I have decided to operate them singly and redo all the wiring to them with fresh 8 gage wire. Hopefully that will smooth out operation. Unfortuneately I can't substitute another manufactuters switches as the track work connect to them is under the upper deck and I can't get to it. If all else fails I will purchase Minitrix controlers and operate them seperately from the control pannel with a small power pack.
Wait, they're wired in series? That's probably the problem them. If you wan tto have two thro with one control switch, like in a crossover, they should be wired in parallel, not series. Ditch the resistors and try the solenoids in parallel.
Thanks Randy..
I tried 100 ohm and 47 ohm 1/2 watt resistors on the common lead from the bus and they cut off all the power to the solenoids completely. I tried smaller resistors until I ended up with 3 10 ohm 1/4 watt resistors in parallel. This works haphazardly. Somtimes the machines work and somtimes not. Previously, the old Minitrix turnouts were powered with Shinohara above table swtch machines and these worked well. All my other switch machines are Atlas HO type under-table switch machine solenoids and these work with the capacitor discharge unit almost all the time. I should mention that my 2 Minitrix switches are wired in series about 6 feet apart to the same pasing siding so that they both switch to the same route when a button is pushed. The wire I used was 8 gage. Do you thing that if I rewire with 12 gauge stranded wire the operation of the Minitrix solenoids would smooth out? Or do you think there is somthing wrong with my CDU? Or do you think that I should wire the turnouts individually?
Easiest place would be a resistor in the common line of each of these switch motors. You don;t want to restrict the power everywhere, just these two. You'll need some fairly hefty resistors, little 1/4 watt ones won't cut it here, but the value need not be high. Maybe 100 ohm, if that's too much try 50 ohm, or two 100 ohm in parallel, if 100 is too small, try 2 in series for 200 ohm.
Hi MRR community,
I recently replaced two old Minitrix curved turnouts with modern ones and powered them with the rather small Minitrix solenoids. I operate my switch motors with a capacitor discharge unit built from plans I found in the N scale Clinchfield Railroad book. When I wired up the Minitrix switch motors and hit the button, the very small solenoids in the Minitrix motors seemed to "bounce" around, leaving the points open or on the opposite rail. It seems the CDU is too powerfull for the small switch motors. Is there somthing I can do to prevent the "bouncing"? Like could I add a resistor to the circuit to reduce the power? If so where would I add the resistor?