Hi everyone!
I wanted to ask if is there is anything in the rules that prohibit one from connecting an LED ring directly to the VRM instead of the PDP.
In addition, is it legally ok to connect a Victor SP controller to the VRM and to a PWM port on the roboRIO to control the LED ring? (not to control a motor).
Thanks a lot!
I can’t find the specific rule that explicitly says you can but you can infer it from the table in R60.
As for connecting a Victor SP, if I recall correctly then you can but if I were you I would check the rules for any restrictions on CUSTOM CIRCUIT.
But be aware that if you intend to connect that circuit to the 12V/2A port in the VRM you must have at least 2 VRM because of R54.
Thanks Omer, I’ll check out the rules you mentioned!
Why do you want to connect a Victor SP to the LED ring? There are probably cheaper ways to get your desired effect.
As Joe_Ross said, it doesn’t really make sense to use a Victor SP to control the LED ring. You could easily achieve something very similar using transistors or a relay (depending on exactly what you want). Victors would just be extra money and weight.
It’s just a solution we thought of that we had lying around. Do you have and recommended alternative solutions?
What exactly are you trying to do with the LEDs? Dim them or just control on/off?
A motor controller is not a custom circuit. From R37, and repeated in the glossary in tabular form:
A CUSTOM CIRCUIT is any electrical COMPONENT of the ROBOT other than motors, pneumatic solenoids, roboRIO, PDP, PCM, VRM, RSL, 120A breaker, motor controllers, relay modules (per R36-B), wireless bridge, or batteries.
Motor controllers must be powered directly from the PDP per R59.
I really like 12V relay modules like this for powering LEDs and other custom circuits. You can control them from a DIO, or a digital pin on an arduino or other co-processor. Similar items are also available in 2, 4, 8, and 16 relay modules if you have multiple items to control separately. Note that because of the optoisolator, many (not all, but most) of these are logic negative - you put a high voltage on the DIO to get the default relay position.
Hi, thanks for you recommendation, I’ll check it out.
We do want to have control over turning the LED on and off, and it seems that your solution is exactly what we are looking for.
Note that a PCM is also a handy way to accomplish this, especially if you already happen to have one powering 12V solenoids on your robot with a port left over. We once ran a second PCM just for an LED ring because it was on hand.
However, if you’re tight on electronics space or don’t have a PCM to spare, a simple 12V relay is the smaller/cheaper solution.
The LED ring from AndyMark has a nominal current of 100 mA. Assuming an LED ring similar to that one is being used and draws less than 500 mA, can’t you just connect the LED Ring to the VRM 12V 500mA slot? That way you only need one VRM and can power both the radio and the LED ring.
Technically, you can.
In practice though the VRM powers the radio, which is mission critical. You don’t want to risk the power to your radio failing because of a LED ring shorting or any other problem with a peripheral device. My advice is always to keep the main VRM just for powering the radio and have a second VRM or other voltage regulator for powering other devices.
Does the PCM have the same limitations? We need to power an arduino, a raspberry pi, and an LED ring. Can the PCM comfortably output 12V from most of its ports? We were thinking of splitting the three between both the PCM and the VRM, but would it be better to run them all through the PCM (with 2 solenoids already in there)? A buck down converter would be needed for the microprocessors from 12 to 5V of course.
Keep in mind the you’ll be limited to 500 mA across all 8 channels. You’ll likely draw to much power for microprocessors.
If you have any lying around, controlling an LED ring from a Spike is super easy. This also incorporates a breaker into the circuit for a short.
You can just always run 2 VRMs, one connected from a 10 amp breaker from a PDP. We ran this last year with no problems. Might be better to use a spike for that, but having an extra VRM can really provide some extra power for 5v electronics and give some overhead in case you want to add more lighting to a robot later.