Is it legal to use a voltage regulator on the output from the digital side car to convert the 6V output to 4.8V power a 4.8V servo?
Ethan
Ethan,
<R48> All electrical loads (motors, actuators, compressors) must be supplied by an approved power regulating device (speed controller, relay module, or Digital Sidecar PWM port) that is controlled by the cRIO-FRC on the ROBOT.
B. Servos must be directly connected to the PWM ports on the Digital Sidecar. They must not be connected to speed controllers or relay modules.
I would expect the answer to be no based on this rule.
Ok, thanks!
Ethan
Is there a way we could legally reduce the voltage to 4.8?
Just a note, most servos that will work on 4.8 Volts will work (better) on 6 volts. I don’t believe I’ve seen a standard hobby servo that won’t take 6 volts, but perhaps they do exist.
Yeah, it says specifically it will not work on a 6V system
Does the removal of the 6V jumpers on the digital sidecar not let it draw enough current? If that works, go ahead and try it. There’s no way a 4.8V servo won’t work on 5V.
Otherwise, no, you can’t use it.
I’ll have to give that a try, I know our other servos don’t work without the jumpers in.
I currently have the question in Q&A just in case voltage regulars are allowed
I noticed something last year that I found somewhat odd. It appeared that the PWM connections on the Digital Sidecar never output 5V, only 6V and only with the jumper in place. I know the old IFI controllers had 5V pins everywhere.
It’s definitely possible that we had a broken sidecar, but it’s also possible that FIRST made a change for some reason.
Yeah, I don’t think its going to work because If I remember correctly I tested the output voltage with no jumper and it wasn’t anything usable
I’m curious, what is the make and model of the servo?
Ethan,
The digital side car jumpers are there to supply 6 volts for servos. If you remove the jumpers there is no voltage. There is no easy way, using the digital side car, to provide 4.8 volts to the servos you linked to in your post. If the GDC allows this variation then we can discuss some alternatives.
Nope, your DSC is operating as intended.
The reason for the jumper is that some hobby speed controllers push voltage on that pin. This is commonly found in RC cars / planes. This would be a problem for our purposes, as they may end up fighting and/or backpowering that rail. So, a simple jumper pulls that circuit out of the equation.
It just so happens that the Victor and the Jaguar don’t do this, so the jumper was just a nuisance in the past, but it lets us be forward compatible for whenever the GDC allows more leeway in motor controller selection.
I propose that you ask the GDC if the following setup is legal:
Remove the jumper from the port you are going to use.
Jump power from one of the DSC’s many 5V pins to the jumper pin closer to the PWM port.
It is kinda ugly, but it does the trick, doesn’t really pose any safety concerns, and might be legal (if unintended) under the current wording.
So basically if they don’t allow the voltage regulator, I’m going to have to find another servo 
Ethan
Yes.
Wouldn’t the power converter included in this years KOP work?
360 CPR
12V to 5V, Step-down, 5A, 25W
Yes it would, but rule <r48> says it must be regulated by an approve power regulator controlled by the cRIO
<R48> All electrical loads (motors, actuators, compressors) must be supplied by an approved power
regulating device (speed controller, relay module, or Digital Sidecar PWM port) that is
controlled by the cRIO-FRC on the ROBOT.A. Each CIM motor and Fisher-Price motor must be connected to one and only one
approved speed controller. These motors must not be connected to relay modules.B. Servos must be directly connected to the PWM ports on the Digital Sidecar. They must
not be connected to speed controllers or relay modules.C. If used, the compressor must be connected to one and only one approved relay module.
D. Each other electrical load (motor or actuator) must be supplied by one and only one
approved speed controller, or one and only one relay module.
$60 for a servo? Wow. Sparkfun and Parallax sell servo’s that are compatible with 6V for $13, and I’m sure there are many other sources too.