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31  Using Arduino / General Electronics / Re: Will 3.3V for a ATMEGA16U2 allow it to create a PC compatible USB port? on: March 04, 2013, 03:29:09 am
Take a look at the datasheet, it talks about different methods for powering the thing if I remember correctly. Various voltages, powered from USB, powered from external source, etc.
32  Using Arduino / Project Guidance / DIY solder mask on: February 27, 2013, 01:08:16 am
Has anyone tried making their own solder mask for homemade PCB's? I'll be using some 0.5mm TQFP packages on an upcoming project and it would be nice if I could get some sort of solder mask between the pins to reduce solder bridges when drag soldering. So far my best idea is to spray the whole board with high temp spray paint and scrape away the paint on the pads with a knife. Alternatively I've seen high temp. felt tip markers which might be less messy. Does this sound feasible? Does real solder mask have some special property which makes it repel solder? And, no, I'm not interested in making a stencil and using UV curable paint.
33  Using Arduino / Project Guidance / Re: Analog Comparator Interrupt on: February 25, 2013, 03:46:48 am
Typically arduino code doesn't have functions for low level stuff like this. You'll have to use good old avr register writes.
34  Using Arduino / Displays / Re: Maximum touchscreen voltage on: February 24, 2013, 07:26:27 pm
Yeah it surprised me too when my first one got shorted. I just redid the less-than-adequate solder job and the problem seems to have gone away; must have been flux residue. However on my first touchscreen the solder job was perfect, yet the short didn't go away over time. Weird.
35  Using Arduino / Displays / Maximum touchscreen voltage on: February 24, 2013, 06:24:31 am
What is typically the maximum voltage I should apply between y+/y- or x+/x- on a resistive touchscreen? the resistance is about 300 and 500 ohms for x and y, respectively. I'm asking because I seem to have broken my first touchscreen by using 3v. The resistance between x- and y- became 100 ohms when the touchscreen wasn't pressed (it should have been infinite ohms). I just got a new touchscreen and was also using 3v when the same thing happened. If I disconnect the power and measure resistance it rises up to ~100k over the course of 30 seconds, so it might be something else. Is 3v way to much for the touchscreen? I'd like to drive it directly from an MCU output.
36  Using Arduino / General Electronics / Re: Hacking RC car to make a child happy - magic dust escaped from board. on: February 20, 2013, 02:37:40 am
I think it would be easier to just buy some transistors which can handle the voltage and solder them in instead
37  Using Arduino / Programming Questions / Re: Converting a byte string to its equivalent byte value on: February 18, 2013, 04:32:41 pm
You're right, an int is 2 bytes. However it probably work the same for most purposes. Now, understand that I never actually learned C (I just picked up what I needed), but I think you can do something like
byte b 〓 atoi(chars); or maybe
byte b 〓 (byte) atoi(chars); and it will be legal (or at least compile). Don't take my word for it though. I don't have a computer here to test it.
38  Using Arduino / Programming Questions / Re: Converting a byte string to its equivalent byte value on: February 18, 2013, 04:17:42 pm
I believe there's a function called atoi() for that purpose. Fairly simple to use, look it up.
39  Using Arduino / Microcontrollers / Re: Copying a sketch from a microcontroller on: February 15, 2013, 05:55:32 pm
Getting the machine code back out is easy with atmel studio or avrdude if you have an isp programmer. There's no way to get the c code back though
40  Using Arduino / General Electronics / Re: Testing a Voltage Regulator on: February 06, 2013, 01:28:34 pm
You bought a negative voltage regulator. Look for a 7805 instead of the 7905
41  Using Arduino / General Electronics / Re: LM317 regulating voltage but no current! on: February 05, 2013, 03:30:28 am
I've had similar problems where I could only get about 9mA from a 317. Turned out that the 317 was blown.
42  Using Arduino / General Electronics / Re: Power off Arduino with on: January 21, 2013, 02:33:05 pm
43  Using Arduino / General Electronics / Re: soldering leads onto a Lipo battery so it can be charged up on: January 16, 2013, 04:33:58 pm
The problem (other than the possibility of explosions) is that the posative terminal is usually made of aluminium and is impossible to solder (from my experience). The only way to connect a wire is to spot weld it on
44  Using Arduino / General Electronics / Re: DIY PCB transfer media on: January 16, 2013, 12:54:16 am
I use a dremel with the thinnest cutting wheel I have. It's certainly not the best way, I'm sure, but I can't think of any other ways to cut out an exact shape. Just gotta make sure I hold my breath!
45  Using Arduino / General Electronics / Re: DIY PCB transfer media on: January 15, 2013, 08:35:09 pm
I didn't have any vinyl laying around, but I had CON-TACT brand "self adhesive decorative covering" so I tried that out, with low expectations. After shoving it through the printer (not a fun experience) I ironed it on max heat like I do with photo paper. The paper came off easily under warm water but some toner stayed on the paper (mostly on the edges, forgot to take a picture). The finish looked a bit rough and I was worried that I had microscopic holes all over, (like I'd heard about elsewhere) so I etched part of it. No microscopic holes as you can see. The distance between traces in the red circle is less than .2 mm, I had no problems with the paper sticking there.
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