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46  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.
47  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
48  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
49  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.
50  Using Arduino / General Electronics / Re: Power off Arduino with on: January 21, 2013, 02:33:05 pm
51  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
52  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!
53  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.
54  Using Arduino / General Electronics / Re: DIY PCB transfer media on: January 15, 2013, 01:29:16 am
Definitely looks promising. I'll have to try this one out. Just have to find this vinyl stuff locally.
55  Using Arduino / General Electronics / Re: DIY PCB transfer media on: January 14, 2013, 04:06:38 pm
How well does it work for thin pitch? (0.5mm) The problem I have with my photo paper is that with fine picthes (less than 1mm) the photo paper gets transfered and stuck in between traces along with the toner. I end up having to scrape in between traces with a knife.
56  Using Arduino / General Electronics / Re: LM317 CC/CV circuit not working on: January 12, 2013, 01:10:24 am
Hmm, they did work when I first tested them after noticing the problem. And I was pulling 500 mA from all of them. Now 2 of them give 6v when set to 5v and one gives 4.8v. I can only pull, guess how much, 7 mA now. Do they usually die this quick or did I get fakes? Who knows. I guess I'll include some in the next Digikey order.
57  Using Arduino / General Electronics / Re: LM317 CC/CV circuit not working on: January 12, 2013, 12:44:41 am
Is this a common failure mode of the LM317? I tried the simple 1 resistor CC circuit and also got about 7 mA no matter what. To be fair, I'm pretty sure all three of these LM317's have been soldered in backwards before in other circuits... I'm not good when it comes to checking the orientation.

EDIT: I'd appreciate it if someone built a simple CC circuit with a 47 ohm resistor and used a 1k resistor as the load. What voltage do you get across the 1k? current through it? I should be getting 26 volts (higher than my supply voltage) instead of 4 volts, and 26 mA instead of 4 mA.

FWIW: with adjust grounded, I get 640mV on the output. Not good?
58  Using Arduino / General Electronics / Re: LM317 CC/CV circuit not working on: January 12, 2013, 12:22:07 am
I get 4.2 volts either side of the resistor with no load. I even tried various values from .1 to 47 ohms and got the same results. I'm no master at LM317 circuits, but if I remember correctly, voltage is controlled by the amount of current going into the adjust pin. I believe the voltage divider (R4 and R5) allow the TL431 to conduct or not conduct depending on output voltage, therefore regulating the voltage if R1 and R2 don't drop it enough (ie. if the current is lower than that set by R1 and R2).

Maybe that means that the TL431 isn't allowing enough current to flow into the adjust pin? What I'm really confused by is R3. What does it do? Removing it makes no noticeable difference.
59  Using Arduino / General Electronics / Re: LM317 CC/CV circuit not working on: January 11, 2013, 09:58:03 pm
At 1000 ohms it's still in constant voltage mode... Go take your wisdom elsewhere please. And I get the same results with a battery instead of a resistor.
60  Using Arduino / Project Guidance / Re: How do you make the current draw from a device gradual instead of instant? on: January 11, 2013, 09:43:32 pm
I've seen it done like this before. First your load receives power through a 1 ohm resistor (fiddle with the value) and the capacitor slowly charges up to the relay turn on voltage. Once the relay latches, it and your load receive full power since the resistor is bypassed. Make sure you use a high wattage resistor.
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