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31  Using Arduino / General Electronics / Re: Guides for soldering? on: August 14, 2014, 11:24:24 am
Get a better model. Save up some money, get a temperature controlled iron. NOT a power control, temperature control. $100 to $150 will get you a decent soldering station.

I bought this one with a digital readout when I updated from a Weller with fixed temperature tips:

http://www.amazon.com/Weller-WESD51-Digital-Soldering-Station/dp/B000ARU9PO/ref=sr_1_7?ie=UTF8&qid=1408032974&sr=8-7&keywords=temperature+soldering+station

Here is one a little cheaper with a calibrated dial and no digital readout:

http://www.amazon.com/Weller-WES51-Analog-Soldering-Station/dp/B000BRC2XU/ref=sr_1_1?ie=UTF8&qid=1408032974&sr=8-1&keywords=temperature+soldering+station

 Do NOT buy one like these:

http://www.amazon.com/Soldering-Station-Features-Continuously-Variable/dp/B0029N70WM/ref=sr_1_3?ie=UTF8&qid=1408032974&sr=8-3&keywords=temperature+soldering+station

http://www.amazon.com/Soldering-Station-Features-Continuously-Variable/dp/B00IOVN0SQ/ref=sr_1_8?ie=UTF8&qid=1408032974&sr=8-8&keywords=temperature+soldering+station

Note that those say variable -power-. Waste of money. Our makerspace at OlyMEGA bought 6 of them. In less than a year, 4 of them are nonworking, the other two are working only because they were repaired with parts from the others.

I'm not saying that you can't solder with a simple pencil iron. I used one for decades. But why not use a decent tool? I went through cheap irons every few years, then I bought a good used Weller WTCP and have used it for a couple of decades. It still works, I bought a new digital control iron mostly for lead-free solder.

As for solder, again, don't cheap out. A good name brand 63/37 will have a better rosin. A pound will last you a really long time, why save $5 on poor solder?
32  Using Arduino / General Electronics / Re: 4x AA Ni-Mh voltage drop on load on: August 14, 2014, 10:00:36 am
All the voltage drops add up. So if you start with a higher voltage, maybe it works.

There is also the matter of corrosion on the ends of the cells.
33  Using Arduino / Project Guidance / Re: where/how to place "blink without delay" on: August 14, 2014, 09:59:27 am
Yes! Better to start using millis() and micros() and get good at it.
34  Using Arduino / General Electronics / Re: Ultrasonic sensor circuit design on: August 14, 2014, 09:46:27 am
Agreed about R5/R6. If the voltages there and at the junction of R1/R2 are even slightly different (I guarantee that they are), then the Op Amp is going to pull the output either really high or really low.

C2 is there to bypass noise at the non-inverting input. Without it, any noise there is amplified as if it were the signal.

I strongly recommend "Op Amps for Everyone". The fourth edition is out:

http://www.amazon.com/Op-Amps-Everyone-Fourth-Edition/dp/0123914957

Earlier versions are available as free download.
35  Using Arduino / General Electronics / Re: 4x AA Ni-Mh voltage drop on load on: August 14, 2014, 09:40:57 am
In my experience, many alligator clip-leads use -very- small wires that are poorly crimped in place. I went through all mine and soldered them, or replaced with larger wires. Some sets of my clip-leads had what looked like about 24 to 26 gauge stranded wire, of not very good quality.
36  Using Arduino / Project Guidance / Re: where/how to place "blink without delay" on: August 14, 2014, 08:24:50 am
And all this is why I really wish they'd just remove the "Blink" sketch from the examples. delay() is a terrible way to do just about anything but blink one lone LED, and you can do that with a blinking LED.
37  Using Arduino / General Electronics / Re: LDR as a sensor on: August 14, 2014, 07:40:30 am
You kind of fooled us into thinking you were asking about using an "LDR as sensor" as that is your topic title, and you spend a lot of time talking about it. BTW, an LDR -is- a sensor. It sounds like you have that part figured out.

Anyway... I'd suggest reposting in "Programming Questions" or "Networking, Protocols, and Devices" with a subject line like "Redbear BLEshield to my iPhone".
38  Using Arduino / General Electronics / Re: Old Computer Power Supply on: August 13, 2014, 11:19:51 pm
You'd hardly need a 10W resistor if it is 10k on 5V. The point is to draw about 500mA, hence 10 ohms on 5V is 500mA, 5V x .5A  = 2.5W. 10W resistors are simpler to find than 5W and give you a bit more headroom.
39  Using Arduino / General Electronics / Re: MC34063 buck with large variable input? help on: August 13, 2014, 11:17:52 pm
Hello, chopped liver here. Did anyone read my posts?
40  Using Arduino / Project Guidance / Re: Designing A Laser Tag System : IR Problems on: August 13, 2014, 06:44:00 pm
http://www4.uwm.edu/usa/safety/chem/laserman.cfm
41  Using Arduino / Motors, Mechanics, and Power / Re: cd motor runs a cd disk on: August 13, 2014, 02:06:11 pm
I'd use millis() or micros(), not delay(), unless you don't plan on your program doing anything else.
42  Using Arduino / General Electronics / Re: DIY cases for you next project on: August 13, 2014, 12:07:18 pm
Even easier, if you have a CNC mill.

Or 3D print them.
43  Using Arduino / General Electronics / Re: what's this phenomenon called? on: August 13, 2014, 12:06:02 pm
If they are the same voltage, I am used to that being called a bipolar power supply. If not the same, then they are just multiple voltage sources, some of them negative (with respect to ground/common).
44  Using Arduino / General Electronics / Re: MC34063 buck with large variable input? help on: August 13, 2014, 12:03:15 pm
http://dics.voicecontrol.ro/tutorials/mc34063/

Enter it as the middle of the voltage range, and a percentage. So:
24 - 7 = 17
17/2 = 8.5
7 + 8.5 = 15.5V middle of the range
8.5/15.5 = 0.548 or 54.8% range



Calculation Results For Step-Down Converter

Vin =   15.50 ±54.8% V
Vout =   5.00 V
Iout =   0.50 A
Vripple =   0.05 V

Vin min =   7.01 V
Ton / Toff =   3.59
Ton + Toff =   10.00 µs (micro seconds)
Toff =   2.18 µs (micro seconds)
Ton =   7.82 µs (micro seconds)
Ct =   312.77 pF
Ipk =   1.00 A
Rsc =   0.30 Ω
Lmin =   11.78 µH
Co =   25.00 µF
R1 =   10.00 kΩ
R2 = ((Vout - 1.25) / 1.25) * R1 =   30.00 kΩ
45  Using Arduino / General Electronics / Re: what's this phenomenon called? on: August 12, 2014, 06:05:10 pm
Hollow State!
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