Question With The Eye Leds

Question

OK, I have my new little trash bot up and running. I have the Movement Panel working fine thanks to Rich and the other guys. I have tested the ports going to the eyes and they work fine. I have used a battery to test the eyes and they work fine. But, when I plug the eyes into the port, they do not light up.

Now, these eyes were made up of a series of LEDs that where on a Reel. You know, the flat type that you get on a reel.

I am giving the EZB +12vdc. But, of course at the ports there is only +5vdc that is going to the LEDs from the EZB.

MovieMaker · Answer

I have figured it out. The LEDs require +12vdc. I don't know Exactly how I am going to do it. But, I will find a way. Thank You guys for helping me.

thetechguru · Answer

Is the EZ-B browning out? I would suspect that more than a couple of LEDs will try to draw more amps than the EZ-B can deliver. You may need a Tip 120 circuit so the EZ-B provides switching but the battery directly drives the LEDs. Alan

thetechguru · Answer

We typed answers at the same time. A TIP120 is still the answer though. Alan

Rich · Answer

Yep, a TIP120/TIP122 circuit, use the Vcc from the battery (12V supply) rather than the digital port's Vcc and 12v will run through the transistor and any components in that circuit. Provided it's a common ground it'll work fine (if not a common ground make it a common ground). So, battery Vcc to the LED strip. LED strip to the collector of the transistor. Emitter of the transistor to the common ground. Signal from the digital port to a 1k resistor, the other side of the resistor to the base of the transistor. Set(DigitalPort, On) to enable and Set(DigitalPort, Off) to disable.

MovieMaker · Answer

Thank You Guys! All is working well now.

OldBotBuilder · Answer

@MovieMaker, Here is the circuit I used to drive the 3 LED strip that forms my EZ Wilber's mouth:  If you are driving a LED strip, no other resistors are needed. (They are in the strip.) The ULN2003A Darlington driver is the equivalent of 7 TIO120/TIP122 circuits. A data sheet is at: https://www.ti.com/lit/ds/symlink/uln2003a.pdf HIGH-VOLTAGE, HIGH-CURRENT DARLINGTON TRANSISTOR ARRAYS FEATURES 500-mA-Rated Collector Current (SingleOutput) High-Voltage Outputs: 50 V Output Clamp Diodes Inputs Compatible With Various Types of Logic Relay-Driver Applications

Dunning-Kruger · Answer

@MovieMaker Hopefully you weren't trying to drive the leds off of the digital pin as opposed to the 5V power pin or else you may have just blown your digital port... You can also use a small 5v relay like this.... plug and play for the ezb...5V relay

thetechguru · Answer

@OldBotBuilder That looks like a very handy little device. Alan

OldBotBuilder · Answer

@thetechguru, Yes it is. I used 1 of them to drive 4, 20 LED strips on my quadcopters.

MovieMaker

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