I wired mine so each is on it's own port. They can connect straight to the EZ-B, no resistor is needed. Between Signal and Ground. Set Digital to turn on and off. Use scripts for sequences i.e. Larson scanner

ok. they are are ok to run off of 5v? And could I wire them all together on one port? e.g. all red visor leds on one port, eyes on another.

The signal wire doesn't supply much current, from memory I think it's 25mA. It's enough to power one and 5V is no problem at all. Powering all 4 would mean each gets 6.25mA which I'd guess isn't enough. You could use a TIP122 circuit.

The headlights either side I tried quickly direct to the EZ-B but nothing happened. It could have been my wiring though but I suspect it was the signal wire not providing enough power. A TIP122 circuit may work but I don't know if 5V is a safe voltage or not.

You may consider a 1k resistor between your 5v output and the LEDs just to knock it down a bit. There also is a adjustable voltage regulator that you can use and just adjust it to the voltage you want. Many of my friends use reastat / variable resistors to cut down current to what they need for the LEDs. Lastly there's the step down converters that work great for this kind of thing too.

Edit - if you want to connect the positive to signal and neg to ground that's fine. The only downside is each led takes up a port. The short leg on a led is the neg, long is positive.
https://www.youtube.com/watch?v=XzhVm3WWyy0&feature=youtube_gdata_player

do we know what voltage the leds in the rad are? if so that will help. could I wire 2 leds together? 2 and 2 to do the visor. then use another battery pack and a manual switch for eye/headlight leds?

Replace the LEDs and you may be able to find some that would work together, or juse a TIP122 circuit to power all 4 as mentioned previously. The TIP122 circuit is probably the best option IMO.

Alternately you could build a new circuit for the head using an I2C extender and control everything individually through the I2CWrite commands, using up 0 digital ports.

what is the tip122 circuit?

http://www.ez-robot.com/Community/Forum/posts.aspx?threadId=3050

how much did it cost you?

and again, could I wire up 2 leds together on the same servo extension? yes or no. I calculated it out, and I could run the leds separately on individual ports. tight squeeze though. don't have enough servo extensions is why I wanted to fit 2 leds on one.

Very little, $2-3 at most I'd guess.

where is a good spot to get the parts? I was thinking ebay, but that would be a pain with shipping and everything else. not in an area with very good electronic shops. I believe online is the only place I could find those parts.

ok. so. I have found everything I need but the strip board on ebay. totals up to $10 with shipping included. again, that doesn't have the strip board included. any idea on where to get the strip board?

You can do it all inline without stripboard.

$10 seems pretty high for a TIP120/TIP122 and a resistor though.


Without stripboard;
Solder the resistor directly to the base of the transistor
Solder the white signal wire to the other side of the resistor
Solder the black ground wire directly to the emitter
Solder the red wire to the anodes of the LEDs
Solder a black wire between the cathodes of the LEDs and the collector

Use heat shrink to keep it nice and neat and free from shorts.

ok thanks. i don't know. i'm looking at my options right now. i could connect the leds to the ezb using servo extensions on individual ports. i counted and i have enough space. what do you think?

That's how I plan to do mine