Tortoise resistors for 12V power supply?

[misterconsister]

I have been using a 4.5V power supply to run several Tortoise machines and the turnouts took about 3 seconds to completely move the points from one side to the other.   Now I've hooked up a 12V (both are 500mA) PS and the transistion time is much faster and louder. 

My questions are, is it possible to slow the machines down by reducing the voltage using resistors, and if so, how would you go about wiring in the resistors - one for each machine, or one on the whole circuit?  How would you calculate the correct resistor value?

Thanks,

Eric

[jbinkley60]

I have been using a 4.5V power supply to run several Tortoise machines and the turnouts took about 3 seconds to completely move the points from one side to the other.   Now I've hooked up a 12V (both are 500mA) PS and the transistion time is much faster and louder. 

My questions are, is it possible to slow the machines down by reducing the voltage using resistors, and if so, how would you go about wiring in the resistors - one for each machine, or one on the whole circuit?  How would you calculate the correct resistor value?

Thanks,

Eric

Try a 470 ohm resistor or something in that range. A Tortoise draws around 15ma of power so a 470ohm resistor will drop approx. 470 x .015ma = 7v .  Thus 12v - 7v =5v will be left across the Tortoise. If it is still too fast try a 560 or 680 ohm.  If it is too slow, try a 390 ohm.

Keep it simple and use one for each Tortoise.

 

[BlueHillsCPR]

Keep it simple and use one for each Tortoise.

 

I'll second that!

 

[oleirish]

I use an cheap AC/DC power supply for my tortoise swiches with an 1 watt, 470 ohm drop resistor on the pos. side of the power supplyIn line with the input , to an row of term. strips in my control pannel.I went the one res per switch way but found  It took to much room ,the set-up I'am useing now saves an lot of space.The first thing I look for is heat on the res,so far none.I agree with changing the speed of the switch ,by changing the RES.At the present I running ten Tortoise switches with on problem.

JIM

 

 

[misterconsister]

Thanks for your replies.

I have a further question.  If I put 2.1V 20mA red & green LEDs in parallel in the circuit to the tortoise power, how do I calculate the resistor?  What voltage does a Tortoise draw?  Do I put a resistor on either side of the LEDs since they are on only one leg of the Tortoise power?

Thanks again,

Eric

[BlueHillsCPR]

Thanks for your replies.

I have a further question.  If I put 2.1V 20mA red & green LEDs in parallel in the circuit to the tortoise power, how do I calculate the resistor?  What voltage does a Tortoise draw?  Do I put a resistor on either side of the LEDs since they are on only one leg of the Tortoise power?

Thanks again,

Eric

If I understand what you are trying to accomplish I don't think you will need any resistors for the leds as is shown in this link.

Wiring panel LEDs in series with the Tortoise™ switch machine

[larak]

Thanks for your replies.

I have a further question.  If I put 2.1V 20mA red & green LEDs in parallel in the circuit to the tortoise power, how do I calculate the resistor?  What voltage does a Tortoise draw?  Do I put a resistor on either side of the LEDs since they are on only one leg of the Tortoise power?

Thanks again,

Eric

360 ohms at 1/4 watt

New supply - {sum of old supply and LED} all divided by current drawn.

 (12v - [4.5v + 2.1v] ) / 15mA

This should leave 4.5 volts at the tortoise = same speed as before.

Karl