Tortoise install question

[bagman]

Hi there

Just installed my first Tortoise with my ME turnout.

2 quick question if you guys could answer please:

1) Once the points are thrown against the stock rails there is a low humming noise from the Tortoise. Is this normal ? Have the Tortoise connected to a 12vDC power supply.

2) How far above the throw bar do you guys cut off the excess piano wire ? Just level with the top of the ties or a shade either way ?

Many thanks for your replies

 

[dgwinup]

1) Yes.  The tortoise is a stall-motor machine.  Power is maintained to keep the points tight against the stock rails.  The hum shouldn't be too loud.  Check that your power supply is giving you 12vdc or less.

2) Personal choice.  I wouldn't cut them so short that they don't reach the top of the ties, but if they are too long, they could interfere with locos, rolling stock and couplers.

Hope this helps.

Darrell, quiet...for now

[cacole]

The humming is not really a good thing, and is an indication that the power supply has poor DC filtering.  The humming is probably caused by an AC ripple frequency that is still in the power going to the Tortoise, and might cause it to overheat and shorten its life span.

If you're using a cheap DC wall wart type of supply, you probably need to get a better one.  Another thing you could do is add more filtering to the power supply by adding an electrolytic capacitor in the range of 10 to 20 mfd, 35 Volt, and a power resistor of around 10 Ohms at 10 Watts to lower the voltage going to the Tortoise.

[rrinker]

 I think you're off a few zeroes on the capacitor size, a filtered DC power supply, even fairly low current, is in the 1000-2200 mfd range. The rest is right on.

 Consider a 9 volt supply instead of 12v, a cheap 12v wall wart with light loading probably puts out closer to 15v. 9v is usually plenty to run a Tortoise, they'll go a little slower, but also be quieter. Unless you plan to put some LEDs in series with the motor for position indicators, then stick with the 12v supply.

                                      --Randy

 

[dstarr]

 The humming is fairly normal.  The Tortoise is a "stall motor" design.  The motor is always powered and motor torque is what keeps the points pressed up against the stock rails.  The motor draws very little current but it draws it all the time.  The humming noise comes from the 60 Hz ripple on your DC supply.  The crudest supplies merely rectify the AC line giving a DC waveform that drops to zero volts 120 times a second.  That is enough AC ripple to make a lot things hum.  Unless the tortoise is getting hot to the touch, its perfectly OK. 

Clipping off the excess piano wire is a eyeball thing.  Too low and it might slip out of the throwbar.  Too high and passing trains get snagged on it.  I get mine down at least level with the railhead.  

As regards filter capacitors.  It will take thousands, perhaps tens of thousands of microfarads to filter out 60 Hz ripple.  And, the filter capacitor will raise the output voltage from 12 to 16-17 volts.  Which is a little bit high for Tortoises.   The capacitor, to be effective in reducing ripple, will charge up to the peak voltage of the rectified DC which is 1.414 times the average or root mean square (RMS) voltage.   

[Sperandeo]

Hello "Bagman," I have a strip of 1/16"-thick brass with a hole drilled for the size of the actuator wire. After installing the Tortoise, I slide the brass strip over the wire and down between the switch points. Then I cut off the wire flush with the top of the brass. You CAN eyeball it, but this method makes the length consistently not too short or too long. It's just right. So long, Andy

[bagman]

Thanks guys for all your replies.

Will look into a slightly lower power supply to see if that make any difference.

Meanwhile I'll monitor the Tortoise to see if they are getting warm to touch, That way I'll know for sure if the lower power supply will help.

Thanks Andy for your tip re the piano wire. I guess the best way to check is to line up a car with couplers installed and see where the interference point will be and cut off just below.

Appreciate all your responses and thank you for your tips.

 

[bobwhitten]

I have 18 or 19 Tortoise switch machines on my layout. I built my own power supply which is well filtered. (1) The Tortoise machines should NOT hum. Your power supply is not well enough filtered. (2) I cut the wires level (or slightly above) with the throwbar holes in the turnouts (Shinohara).