What is the current draw of the $4 servo motors you have been ordering through the Internet? I am looking for something that draws under 20ma so I can wire bi-color LED's in series for panel lamps.
Also, what are you using for logic if you want to DCC stationary decoder these motors?
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
I hooked up the peco switch with a servo motor that I made after the MR article came out to an ammeter. It is a 40 year old servo and I don't know if I did it right but it was reading over 300ma when stalled. If you are using the servo as a stall motor couldn't you just hook the LED across the motor leads with the proper resistor?
I redid the test with a meter that reads up to 10A. It is drawing .5 amp when stalled. I hope this helps.
One could use a resistor and wire the LED across the power to the servo. But, the series install at the panel(especially with 20-40 turnouts) does not generate the heat off the resistor or limit the power to the motor.
The Tortoise install is quick, simple and just works. The problem is cost & the size of the Tortoise. 300ma sure is a lot of current draw! I have a 850ma 'wall wart' that powers all of my Tortoise motors I looked at the Micro-Mark 'Switchtender', but is draws about 60ma at stall(even wih the supplied current limiting resistors). The Proto87 'Mole' draws about 30ma. I have 10 Tortoises installed right now, but I will need another 14 in the near future.
I may be showing my ignorance but can you power Tortoise switch machines via a DC transformer? I believe that the Digitrax Zephyr allows you to plug a DC outlet into it (I may be wrong). Would this solve the power draw issues?
Curt Webb
The Late Great Pennsylvania Railroad
http://s1082.photobucket.com/albums/j372/curtwbb/
I'm pretty sure they draw more than 20ma. The signal to a servo isn't a steady DC voltage anyway, it's a pulse train, equal positive and negative put the servo in the center, more positive moves it one way, more negative moves it the opposite way.
The Tam Valley controllers have indicator LEDs in them already. There are also provisions to add SPDT or DPDT relays for frog power and other stuff. Even the non-DCC controllers have the LEDs on the pushbutton controls.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Curt Webb I may be showing my ignorance but can you power Tortoise switch machines via a DC transformer? I believe that the Digitrax Zephyr allows you to plug a DC outlet into it (I may be wrong). Would this solve the power draw issues?
Curt,
You are correct.
The Tortoise is designed to be powered by a DC power supply up to 12 volts. The power supply does not need to be filtered. The Tortoise will draw 4 ma. during operation and 15 to 16 ma. at stall. The Tortoise can also be powered by an AC power supply if set up in conjunction with two diodes.
I am not familiar with the Digitrax Zephyr, so I cannot address that issue.
Rich
Alton Junction
There's nothign that owuld need to be hooked up to the Zephyr. This is ont of the nice things about Tortoise motors vs the attempted competiton - they draw only about 15ma stalled so they can be driven with simple electornics, and since 15ma is perfectly safe for LEDs, you cna install LEDs in series with the motor with no resistors and the LEDs will show the turnout position. None of the other are this simple to hook up, even the Switchmaster motors come with a resistor to use to limit the current draw.
ANd the results of 300ma on the servo - yet another point to why I really did not like seeing that article in MR. I will repeat it again - RC servos ARE NOT STALL MOTORS nor are they intended to operate that way. They rely on that internal circuit to provide feedback to STOP the motor when the position matches the commanded position. At 300-500ma per when stalled, I cannot imagine them holding up long term when used per the MR article.
If you want to use servos, Tam Valley and some others have proper controllers to drive them the way they are meant to be driven. I get my servos on eBay for $3 or less each, and have combined them with the Tam Valley Singlet product (save a couple bucks, get the kit - all you have to do is solder on 2 LEDs and 2 pushbuttons!). The combined cost of a servo and the Singlet is less than the retail price of a Tortoise, and for that money you get a pushbutton controller for the fascia with LED indicators AND it's also a DCC stationary decoder so you cna have DCC control as well as the local buttons. If you have no desire for DCC control, there is a different product that controls 8 servos and also has pushbuttons with LEDs. Add 8 servos and the cost per turnout there is generally less than you cna buy Tortoises for.
Every other Tortoise alternative for powered turnotu operation comes up short in some way. The Switch Tender from Micro-Mark seems particularly useless. Manual is always the cheapest, but for hard to reach turnouts sometimes you just need to power them - servos used ot be far too expensive, mainly because of the required controllers, but microcontrollers are super cheap these days and most of them have multiple PWM outputs to drive servos, so controllers have gotten a lot cheaper. Today I would say servos are the best way to go, followed by the Tortoise. After that, I think I'd just set mine up for manual operation before I'd use any of the other kinds of switch motors.
try these people
www.tamvalleydepot.com
They have a micro servo with decoder that I picked up an an LHS for 18 bucks.
The servo without decoder is $4.50 from them and cheaper from wholesalers.
I don't know about this particular servo but everything I've read for micro servo's has been between 150 and 750ma peak.
Springfield PA
Here you can get them for under 3 bucks but the tamvalley verson comes with additional hardware
http://www.hobbypartz.com/topromisesg9.html
Only thing that appears to be missing there are the bushings the Tam Vally ones have (and the cheap ones I get on eBay have as well), which aren't really needed - rubber bushings to isolate the servo from the vibration of the airplane motor.
My freidn ahs a basic 1/2: plywood subroadbed, he just sticks the servos on right under the plywood with a glue he found, it's not Gorilla glue, it's more of a rubber cement, works well. No linkage oterh than a short piece of piano wire to run up to the throwbar. The whoel thing is so small that you cna put a servo just about anywhere. On my layout, with 4" of foam to go through, I use a nifty servo mount made my Motrak, which Tam Valley also sells. The serveo attached to the mount with a screw, the mount screws to the bottom of the layout liek a Tortoise, only smaller. Operation is exactly the same as a Tortoise then - the mount has a fulcrum hole and the end of the wire wiggles back and forth like with a Tortoise. Same deal - drill a hole under the throwbar (I do it BEFORE mounting the turnout!) and poke the wire up through the throwbar.
I have a single Tam valley servo with singlet decoder I picked up but haven't had the chance to play with yet. Is the torque strong enough to push a PECO with the spring tension on the low setting?
It should be, but when connected them to a solid action motor like a Tortoise or a servo, why wouldn't you remove the spring for smoother operation? The Peco motors need the spring but types that lock into position don't need it and it defeats the slow motion action.
I've had luck with loosening the spring and using with the torti. It just gives me the ability to leave the switch as is for any future change in plans. The spring can be removed but it would surely be lost.
How do you loosten the spring? I know how to remove it & lose most of them but loosten it?
Bob D As long as you surface as many times as you dive you`ll be alive to read these posts.
The spring housing slides back and forth with a thumbnail or small screw driver. Push it away from the spring and it loses half of it's strength. By the way this is for code 100 peco turnouts. I don't know if it is the same for code 83.
They describe it a little in this article:
http://www.loystoys.com/peco/about-turnouts.html
You should be able to put a resistor in series with the servo motor to reduce the current. However, there is going to be a trade off. Getting the current down to 20ma may not allow the servo to have enough power to move a stiff turnout.
EDIT
Do you remember back in the days of constant lighting on DC locomotives? Where the motor current ran through two back to back diodes and a 1.5 volt mini bulb was wired across the diodes? Something like that may work with an LED too.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
Since servo's are relatively new in this hobby we'd probably need some more info. For instance if the servo is rated a 120ma we need to know what voltage it's based on. If it's at 5 volts then for a 12 volt source the current is less than half.
Most current servos are designed to work on 5 volts. The reduced voltage means fewer batteries in your airplane, where weight is critical. It also means they can be directly driven off a common PIC or other microcontroller. The motors aren;t meant to be used with 12 volts.
I would say any 9G and bigger servo will work fine with Peco, they can push pretty hard. The 4.3 and smaller super micro servos might not have enough power. Bascially, if it works with a Tortoise it will work fine with a servo.