Relay to control 2 outputs

[Micah Chetrit]

Hey everyone.
I have an off season project to make LED rods and put them on the robot and get them to light up in patterns (I am also a programmer). Being that there are going to be 4 rods, I thought I could save space and money by using only two Spike relays, attaching two Positive wires to it and using a common ground that isn't run through a relay.
If I recall right, this has been used for solenoids (? might be wrong). In my mind it should work, is there any reason it shouldn't?
Secondly, is it legal to control two outputs with one controller? (haven't read rules for a long time, I forgot many of them)

Thanks in advance,
Micah

[apalrd]

This is an off-season project, legality is not an issue.

There is no reason why it wouldn't work. In LV at least, the Spike has four output states (Off, Forward, Reverse, and On). Fwd will set one on and the other off, Reverse will set the second one on and the first one off, and On will turn them both on.

[Micah Chetrit]

the reason legality is an issue is that I am making two sets, one for the current bot, and one for next years bot (using the same code)

[Travis Hoffman]

Originally Posted by Micah Chetrit

the reason legality is an issue is that I am making two sets, one for the current bot, and one for next years bot (using the same code)

See R42. Controlling 2 solenoid or low-current light outputs with one Spike has been legal for many years. As long as you properly send the negative wires back to a black PD board negative terminal (presumed ok to splice the negative leads to fit into a single terminal), you should be fine.

However, what would not be legal is preparing these LED arrays and wire harnesses for use on a 2012 FRC robot - you must wait to perform all such work after kickoff of the 2012 season, during approved robot work times.

[Micah Chetrit]

Oh, I didn't know about that.
what specifically is forbidden? Can I wire the leds and put them in a tube (therefore just creating a part), but not wire it to a relay? or is making custom parts before season not legal?

[Travis Hoffman]

Originally Posted by Micah Chetrit

Oh, I didn't know about that.
what specifically is forbidden? Can I wire the leds and put them in a tube (therefore just creating a part), but not wire it to a relay? or is making custom parts before season not legal?

The latter case is true. Until the rules change, you cannot fabricate custom parts or construct custom assemblies for your official FRC robot prior to the start of the season. This is one of the core tenets of the FRC program - every team must engineer their robot within the same time window.

[Micah Chetrit]

Thank you for pointing that out. I guess I only have to make one set this summer then.

[Al Skierkiewicz]

Micah,
It is also possible that this wiring method would be illegal during next year's game and rules. I would hope that the GDC allows teams to use this method but you never know for sure. As stated the Spike is capable of switching either or both outputs between high and low states. The manual for the Spike explains this.

[Hugh Meyer]

Micah,

If you connect them to a Jaguar or Victor you could dim them. With different colors that could give you some interesting effects. You would need to put the LEDs in series to be able to tolerate the 12 volts...maybe 6 LEDs and a current limiting resistor. Just an idea...

-Hugh

[slijin]

Just as a note, what Travis said is perfectly true; any design done preseason is not legal for use during competition. However, if the design is modified (i.e. improved or optimized during competition) for the robot, then it is indeed legal.

[Warlord]

Although it is worth noting that given that this seems to be more decorative than functional - designing a whole drive train in the offseason is one thing, designing some pretty lights is something else entirely. I wouldn't worry too much about breaking the intent of the "6 weeks" thing.

[Micah Chetrit]

Originally Posted by Hugh Meyer

Micah,

If you connect them to a Jaguar or Victor you could dim them. With different colors that could give you some interesting effects. You would need to put the LEDs in series to be able to tolerate the 12 volts...maybe 6 LEDs and a current limiting resistor. Just an idea...

-Hugh

Thanks for the Jag Idea, it sounds like a great idea. I was going to use team color LEDs though, so I am not going to lay too much with colors.

I was planning to put them in parallel however and use a Zenner Diode to regulate the voltage, simply because a 6 led chain isn't very long. I Have not tested the idea yet. I have never used Zenner Diodes before, Any opinion/experience with it? Other ideas?

[Ether]

Originally Posted by Micah Chetrit

I was planning to put them in parallel however and use a Zenner Diode to regulate the voltage, simply because a 6 led chain isn't very long.

You can make the chain as long as you like.

I have never used Zenner Diodes before, Any opinion/experience with it?

You didn't mention a resistor. Could you post a sketch showing how you plan to use the Zener to regulate the voltage to the LEDs?