Re: Computer Power Supply and Turnout Problems


Hi Wayne,

The problem may be that it is not providing power because there is not sufficient minimum draw on the 5 volt lines. Some power supplies for PC's require a minimum current draw on the 5 volt lines for it to kick in to provide all the other voltages. You can check the manual, probably on line, for what that number is. I have found that 1 amp usually works o.k. For yours, it may be less. so do check the manual, if you can find one.


Mike G.

On 10/7/2019 2:01 PM, Wayne Swearingen wrote:
I have a 350w computer power supply that I am using for turnout motor control. I bought one of those adapters that plug into the motherboard pigtail and break-out 12v +/- 5v and 3v

There are currently about 18 stall motors connected to it, not Tortoise, the plain black stall motors. With everything hooked up the negative side of the power supply drops down to about 9v which causes problems with points since we have around 1k ohm resistors soldered in place on each motor. 
I've read up on the majority of the stall motors and the consensus seems to be 20 mA as the rule of thumb per motor. I did confirm and saw that the negative side of the power supply is only putting out .8 AMPS while the positive side puts out considerably more. By my math 20 mA x 18 motors doesn't put me in danger on the negative side but something is pulling the volts down.

Join to automatically receive all group messages.