tomikawaTT TomDiehl taildisk Scott you said your supply was AC. Don't you need DC to operate a switch machine coil? Rob No, the Peco switch machine is the simple twin coil design, two electromagnets that pull the bar one way or the other depending on which one is energized. They work on AC or DC. Stall motors (Tortoise isn't the only one) run on DC. Simple coils can run on anything; AC, half-wave DC, filtered DC (aka Capacitive Discharge) or even a pair of lantern batteries in series.
TomDiehl taildisk Scott you said your supply was AC. Don't you need DC to operate a switch machine coil? Rob No, the Peco switch machine is the simple twin coil design, two electromagnets that pull the bar one way or the other depending on which one is energized. They work on AC or DC.
taildisk Scott you said your supply was AC. Don't you need DC to operate a switch machine coil? Rob
Scott you said your supply was AC. Don't you need DC to operate a switch machine coil?
Rob
No, the Peco switch machine is the simple twin coil design, two electromagnets that pull the bar one way or the other depending on which one is energized. They work on AC or DC.
Stall motors (Tortoise isn't the only one) run on DC. Simple coils can run on anything; AC, half-wave DC, filtered DC (aka Capacitive Discharge) or even a pair of lantern batteries in series.
Don't confuse the poor guy, a Peco switch machine is NOT a stall motor type.
Also filtered DC and Capacitive Discharge type power supplies are two different things. In filtered DC, the capacitor is connected across the output leads to smooth out the rectified DC (60 or 120 Hz, depending on the diode setup). On Capacitive Discharge, the capacitor is connected to "charge up" with the supply voltage, then discharge when a switch is thrown.
Rob, what I meant is that the VPP determines the actual amperage at peak - thereby giving an instantaneous 'kick' to the armature, repeated 60 times per second. (Yes, the machine will buzz if the probe is held in contact with the stud.)
The same circuit will work with a stall motor, but with a continuous-contact SPDT switch. A small non-polarized capacitor across the Tortoise motor connections will help to fill in the low spots on the wave form and reduce the buzzing to inaudibility.
Granted that my coils, when energized, work on half-wave DC. If I used two wires and removed the splitter diodes the coils would receive full-wave AC, which is equally effective.
Chuck (Modeling Central Japan in September, 1964)
Scott has not said it, but I think his circuit would be similar to what TomikawaTT wrote about. That is the use of diodes to steer the current in the circuit. So in this case the coil see's only one half of the supplies wave form, in effect the coil gets pulses of current only flowing in the one direction, the coil is powered by DIRECT CURRENT. The diodes in the circuit (the steering ones) are acting as the rectifier for the circuit.
Also Voltage does not cause an armature to move. You can have 1,000 volts but if the circuit resistance is very high such that only 1 mAmp can flow then you would need a very special coil to move an armature. Current, or more correctly current of sufficient value, is what causes an armature to move.
One stunt I use to reduce the number of wires is to use diode separation and power both coils of a machine through a single wire. One pair of diodes behind the panel, connected to the studs I mentioned above, puts half-wave positive DC or half-wave negative DC onto the wire. Another pair of diodes at the switch machine routes positive to one coil and negative to the other. Power is 12.6 VAC from a three amp transformer, one end to the probe, the other to the turnout return bus. If the turnout power wire has to run more than a few feet, be connected to terminals on more than one terminal strip or pass through a plug-in connector the reduced cost of the panel-to-machine connection more than makes up for the price of four ten-for-a-dollar diodes.
Granted that a meter, reading RMS voltage, only shows 6 vdc on the connecting wire. VPP is still close to 17 volts, and VPP is what moves the armature.
Chuck (Modeling Central Japan in September, 1964 - with twin-coil switch machines)
Thanks to all for the great input. I'm I missing something or is the math actually in favor of a Tortoise machine. You can get a Tortoise on line from MB Klein for $14. The Peco switch motor is $10.50 and the Toggle switch is $5.50, plus I only have to pay postage once on Tortoise, because I don't have to order from two different places. Are their other components (cost) for the Tortoise that I would need?
I am stuck now with what I have, but I am talkin about for the future when I plan to expand the layout.
Reading the customer's reviews on this product, it sounds like it's not a momentary contact type switch. Pushing the button toggles it from one connection to the other with no "Off" position. Note the third review:
http://www.radioshack.com/product/index.jsp?productId=2062541&tab=custRatings
The Shack doesn't seem to have what you need, try Digi-Key
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=679-1219-ND
Note they list the function as "Mom-Off-Mom" which means it's momentary contact to both sides with a center off position.
I agree with jeffery-wimberly and CSX Robert, although the switch jeffery recommends is rather expensive. After much consideration I decided to go with 4-pole-double-throw switches and a pushbutton. I connect the pushbutton and one of the poles on the switch just like the Atlas control switch. I use the other three poles for indicator lights on the control panel, control lights on the layout, frog-powering, or even powering a section of track so that a loco will stop automatically if it approaches a track switch set against it.
I'll be the first to admit that the lights on the control panel are redundant because the position of the toggle reveals the position of the track switch. I just like the look of red and green lights on my control panel.
Downside is that the track switches and the control panel can get out of agreement if someone moves a track switch by hand. Grandchildren do things like that. I've done it, too, when I've been on the other side of the table and just reached in to change a track switch.
Tortoise machines avoid all these issues, but I decided to save a few bucks.
Powering RIX and KTM (formerly imported by Kemtron) switch machines, I use a stud and probe system. The studs are brass screws, inserted in the control panel track diagram at appropriate locatiions. The probe is a stereo plug with power to the tip only, Touch probe to stud, switch machine activates. When not in use the probe plugs into an unpowered stereo jack on the side of the panel.
Using that system, there is absolutely no possibility of a control short circuit or failure smoking a switch machine. Plus, you can wire all the switch machines in a good size yard for the price of a couple of decent-quality toggle switches.
I may be wrong but this switch looks like it energizes both outside terminals from the center terminal at the same time. I've never liked the mini switches myself as I've welded a few closed. They just can't take the power. I use a heavier toggle type momentary DPDT switch (Radio Shack #275-709) for my Bachmann switch machines. I have them set up with SPST toggles so I can control two switch machines with each DPDT.
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
The switch should have 3 positons and spring return to the center position.
That R/S switch only has a 3 amp rating - I suspect you 'welded' the contacts together! The momentary current draw can easily be up to 10 amps for a few milliseconds. I would look for a SPDT momentary 'toggle' switch with at least a 10 amp rating. Try Mouser or Digikey(better prices). Also, invest in a good Capacitive Discharge unit to protect you switch machines. I had R/S miniature SPDT toggles about 10-15 years ago, driving Kemtron switch machines - and had a contact 'tack' - burned up switch machine!
I use Tortoise machine now....
Jim Bernier
Modeling BNSF and Milwaukee Road in SW Wisconsin
Hello Scott,
I have Peco turnouts also but have yet to wire one. However, from what I have read you will need to add a Capacitive Discharge Circuit to over come the spring tension of the Peco turnout. This momentarily stores up an extra amount of electrical current and gives the switch machine a shot in the arm so to speak.
I'm sure you will receive other replies confirming this and how to do it.
If not do a search on the forum for Peco switch machines.
I'll be learning as well.
Good luck !
Bob
Don't Ever Give Up
I am replacing atlas control boxes with SPDT Momentary switch from radioshack part #275-1549. I am using PECO switch machines. I wired based on instructions from an older thread on the forum. One wire from AC power to common going to PECO switch machine and other wire from AC to center pole on radio shack switch, and other wires from peco switch machine to right and left poles on radio schack switch. When I turn on the power source I am getting constance buzz without pushing button. What I'm I doing wrong? Is the problem that the radio shack switch is not open in both positions (On off On). The web site doesn't say.
Thanks,
Scott