Powering Robot Controller without breaker panel, etc.

[geeknerd99]

Currently lacking a robot to mount the camera on, we've mounted the camera on an Edubot that can drive around and simulate the larger robot tracking the target. We've mounted the full-size RC onto the frame, and we'd like to power the 12v input using 12v in AAs. We're going to wire a switch and a fuse into the circuitry so that we have some sort of control.

Basically put, is this safe?

[KenWittlief]

Im trying to figure out how to power the EDU motors that way?

dont they run off the 7.2 or 5V servo outputs on the EDU controller?

[geeknerd99]

Oh right.... I seem to have forgotten that. Wasn't my idea to do this, I'm just the only person on my team active on CD, so I had to ask. Err... what do we do then?

[KenWittlief]

in the past teams have use the edu bot with the retro-reflective sensors (which run on 12V) - using the edu bot controller, but adding a 12V battery circuit to power the sensors

but it sounds like you really need the camera with the full size robot controller.

this might take some doing.....

[thinking]

[KenWittlief]

BTW, the camera itself is 7.2 V and you need the little backup battery to make it work, right?

not 12V into the camera? That would be bad

[geeknerd99]

Yeah, I think it runs off the backup battery. We were going to put that in anyways. Basically, we're running nothing but the camera and 2 motors, but under the same conditions as we would on the full-size robot.

[steven114]

Ken: The camera has an internal regulator; the docs say that it takes between 6 and 15 volts or so.

[Matt Krass]

We do exactly that, we have a box with 8 AAs and a switch that connects to the main, that powers the controller and radio/tether and the backup battery powers servos (and EDU motors) as well as the Camera.

Keep in mind it won't last terribly long in that mode though, so keep a few backup batteries ready.

Also if the "Main" (The AAs) get low the backups die even faster. It would help to get your hands on a Vex battery kit for this, or even a Vex kit, not sure if the controller can interface to the camera though.

[Alan Anderson]

Ken: The camera has an internal regulator; the docs say that it takes between 6 and 15 volts or so.
Make sure you're not supplying 12v to the servos, though. There's a jumper on the camera to use separate servo supply if you want to.

[geeknerd99]

We do exactly that, we have a box with 8 AAs and a switch that connects to the main, that powers the controller and radio/tether and the backup battery powers servos (and EDU motors) as well as the Camera.

I understand how the backup battery would power the servos and EDU motors, but last time I checked, there's 3 pins on the RC board, and 4 pins on the EDU motor. Are you guys working black magic or something?

Of course, by black magic, I mean custom circuitry. ;)

[Mark McLeod]

Matt's using Vex servos and they only have 3-wires.

The extra (orange) wire on the Edu servo is a second power line.
To hook it up to the regular FRC controller you need to construct an adaptor cable to go from 4-pins to a 3-pin connector and a second connector that just uses the power from another 3-pin connection. See the Edu-RC-2004_Ref_Guide document.pdf

[scottmso]

I plugged the 7.2V into my camera with an adapter (made from putting together a PWM cable and the NiCad battery cable) and it worked fine for me. However, someone else said they did the same thing and it fried their camera. Just make sure that you plug everything in the right way, or you WILL fry your camera.

[Daniel Brim]

Use a robot controller to power the camera for safety of camera.

I believe RC contains a PTC in the 7.2v path,
The PTC goes to high resistance upon overcurrent, protecting the camera, then it automatically resets.

Last year we blew the camera tantalum filter capacitors using direct connect (correct polarity) which the PTC would have avoided.

Dale(engr294]

[perilous]

We do exactly that, we have a box with 8 AAs and a switch that connects to the main, that powers the controller and radio/tether and the backup battery powers servos (and EDU motors) as well as the Camera.

Keep in mind it won't last terribly long in that mode though, so keep a few backup batteries ready.

Also if the "Main" (The AAs) get low the backups die even faster. It would help to get your hands on a Vex battery kit for this, or even a Vex kit, not sure if the controller can interface to the camera though.
Last year when I was developing camera code for a final project I used an old 12v power supply from a broken router to power the RC and connected the camera like you would have it on actual bot. This worked well and allowed for unlimited testing without a bot at my disposal (hard to transport a bot back and forth to school).

[Rick Thornbro]

Just a quick reminder, be sure to connect the polarity correctly. One of our students released magic smoke from a camera last year. Hard to put back in.