tortise

[Alantrains]

Given that a tortoise uses 30ma at 12 Volts. A  12 volt supply would need  16 X 30=480ma Max so a 500ma will be sufficient.

 

[jrbernier]

  A Tortoise at full stall only draws 18ma.  18ma times 16 Tortoise motors equals 288ma.  500ma is more than enough.   I have a 15VAC wall wart with 850ma capacity(Old cordless tool charger).  I use a pair of diodes to make a split power supply like the example in the Tortoise instructions.  I get about 9VDC half wave for my Tortoises to power my 30 Tortoise motors - more than enough power.

Jim

[KHM60]

i had a 1500ma RS walwart but when hooking up one of the leads to a junction block i shorted it out and was told the walwart wasn't any good anymore, no reset button and no automatic reset i believe i fried it, so i was told by a RS employee

[KHM60]

i do have an old walwart charger from something, it says it puts out 12v@800ma OK?

[Phoebe Vet]

It may very well be fried, but before you throw it out look at it carefully.  Some wall warts have a fuse in the plug.  If not, some plugs can be disassembled.  It may have just burned a wire.

[KHM60]

will give it a look thanks

[Texas Zepher]

richhotrain

Texas Zepher:

 If one is going the DC route get the most pure filtered DC power supply availalble.

 

TZ, when you say to get the most pure filtered DC power supply available, what exactly does that mean?  If the MRC Railpower 1370 power pack such an animal?

When AC current is converted to DC the most simple process (a bridge rectifier) just takes the normal sine wave and flips the negative half of the cycle to be positive.  It basically makes a set of humps where the voltage goes from zero to the max voltage at 2x the frequency.  In the USA all power is 60 cycles per second so a straight conversion results in the power going from zero to 12V 120 times a second.   On the other hand a battery produces a true flat line voltage at 12Vs.  A battery could be considered a pure filtered DC.  One way to smooth out the voltage from a straight bridge rectifier is to put a capacitor on the DC output.  As the capacitor charges and discharges it tends to fill the gap between the humps in the rectifed DC power.

Unfortunately I do not know anything about the MRC Railpower 1370 other than it is has a full wave rectification.  I did find this post from a few years back about the MRC 1370 -->   http://cs.trains.com/trccs/forums/t/29520.aspx

[richhotrain]

Texas Zepher

richhotrain:

Texas Zepher:

 If one is going the DC route get the most pure filtered DC power supply availalble.

 

TZ, when you say to get the most pure filtered DC power supply available, what exactly does that mean?  If the MRC Railpower 1370 power pack such an animal?

When AC current is converted to DC the most simple process (a bridge rectifier) just takes the normal sine wave and flips the negative half of the cycle to be positive.  It basically makes a set of humps where the voltage goes from zero to the max voltage at 2x the frequency.  In the USA all power is 60 cycles per second so a straight conversion results in the power going from zero to 12V 120 times a second.   On the other hand a battery produces a true flat line voltage at 12Vs.  A battery could be considered a pure filtered DC.  One way to smooth out the voltage from a straight bridge rectifier is to put a capacitor on the DC output.  As the capacitor charges and discharges it tends to fill the gap between the humps in the rectifed DC power.

Unfortunately I do not know anything about the MRC Railpower 1370 other than it is has a full wave rectification.  I did find this post from a few years back about the MRC 1370 -->   http://cs.trains.com/trccs/forums/t/29520.aspx

Thanks, TZ.