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1  Using Arduino / General Electronics / Re: Completely confused about MOSFETs on: September 17, 2013, 02:48:55 pm
Thanks for the replies. I switched the drain and source connections, but it's still not working as I would expect.

The LED strip is now glowing very faintly and stays that way, it does not seem to matter if I put 0V or 5V on the gate of the mosfet. Even if I disconnect the PWM pin from the gate the LED strip glows faintly. Does the MOSFET allow a small amount of current to flow no matter what the charge on the gate pin is?

Sooo, I'm guessing that the MOSFET indeed doesn't turn fully ON with 5V. Which again has me confused a little. The LED strip should draw somewhere around 200mA-250mA per color channel, and if I look at the graphs in the IRF510 datasheet, 5V should be enough to allow that much current to flow. I agree that the IRF510 might be overkill for this application, but it should work, no?
2  Using Arduino / General Electronics / Completely confused about MOSFETs on: September 17, 2013, 01:55:33 pm
First off, let me start by saying I'm pretty new to electronics, and I could really use some help.

Here's what I'm trying to do. I want to control a 12V RGB LED strip with an arduino. Right now I'm focusing on just getting one of the color channels to work, expanding to all 3 colors should be trivial.
The LED strip has a common positive connection. I'm using a IRF510 mosfet.

Now I'm completely confused as to how I should wire the thing up. I connected a PWM pin of the arduino to the gate of the MOSFET and a pull-down resistor to ground. The positive lead of the LED strip is connected to the +V connection of the power supply. One of the color channels of the LED strip is connected to the source of the mosfet. The drain of the mosfet is connected to ground.
I also connected the ground of the arduino to the -V of the 12V power supply. (picture included as attachment, just imagine the single LED in the image is a LED strip)

When I do this, the LED strip lights up no matter what. Even if I disconnect the gate pin, the LED strip will still light up ... which confuses me to no end. How can current flow through the mosfet if there is no charge on the gate? No matter what I do I can't seem to get the thing to work like I want it to.
3  Using Arduino / Networking, Protocols, and Devices / nrf24l01 with RF24 library: lots of interference on: March 19, 2013, 12:34:20 pm
Hey guys,

I just got a set of nrf24l01 modules and connected them to a nano. I got the RF24 library and I'm running the scanner example sketch. If I understand correctly, ideally it would print out all zero's all the time (meaning no data was found on any of the channels).

At first this was the case, but now I'm seeing lots of interference. Here is some example output of the scanner sketch:

As you can see, every channel is cluttered with interference.
When I run the GettingStarted sketch in transmitter mode I get the following output:
Now sending 46056...ok...Got response 4294967295, round-trip delay: 46058
Now sending 47058...ok...Got response 4294967295, round-trip delay: 47060
Now sending 48061...ok...Got response 4294967295, round-trip delay: 48063
Now sending 49063...ok...Got response 4294967295, round-trip delay: 49065
Now sending 50065...ok...Got response 4294967295, round-trip delay: 50068
Now sending 51067...ok...Got response 4294967295, round-trip delay: 51070
Now sending 52070...ok...Got response 4294967295, round-trip delay: 52073
Now sending 53072...ok...Got response 4294967295, round-trip delay: 53075
Now sending 54075...ok...Got response 4294967295, round-trip delay: 54077
Now sending 55077...ok...Got response 4294967295, round-trip delay: 55079
Now sending 56080...ok...Got response 4294967295, round-trip delay: 56082

If you look at the received response you can see that it is not the same as the original data and it looks like interference again.
Any idea what's going on here?
4  Using Arduino / Microcontrollers / Re: Burning the bootloader to a nano using uno as ISP on: November 18, 2012, 11:48:38 am
Alright, it works! Thanks a lot smiley
5  Using Arduino / Microcontrollers / Re: Burning the bootloader to a nano using uno as ISP on: November 18, 2012, 08:50:36 am
Thanks! The guide is a lot clearer than the others I found.

Unfortunately I do not have a 16mhz oscillator and I was wondering if I could do it without one. They aren't expensive, but I would like to have my nano up and running as fast as possible, and if I order one from eBay it would take some time to arrive.
I saw somewhere it is possible to use the internal oscillator of the atmega on the nano. How do I do this?
6  Using Arduino / Microcontrollers / Burning the bootloader to a nano using uno as ISP on: November 17, 2012, 09:16:35 am

I just got my nano v3.0 and I'm excited to start working with it. Unfortunately it came without a bootloader installed. Now I'm trying to figure out how to burn the bootloader onto my nano by using the uno rev3 I have as an arduinoISP.

I think I understand all the steps I have to do in the IDE, but I'm not sure about the connections I made.
I connected pins 11,12,13 from the uno to the nano, I connected pin 10 from the nano to the reset of the uno, I put a 10µF capacitor from reset to GND on the uno. I should also mention that I'm powering the nano with a USB cable connected to my pc (so, not using the power pins from the uno).

I then get this error:
avrdude: Send: P [50]   [20]
avrdude: Recv:
avrdude: stk500_program_enable(): protocol error, expect=0x14, resp=0x50
avrdude: initialization failed, rc=-1
         Double check connections and try again, or use -F to override
         this check.

avrdude: Send: Q [51]   [20]
avrdude: Recv:
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

avrdude done.  Thank you.

I'm guessing I just don't have everything wired the way I should. Can anyone help me out here?
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