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1  Using Arduino / General Electronics / Re: Which power supply needed for a 20W halogen bulb? on: July 05, 2014, 10:53:58 am
Halogen bulbs must be used behind a secondary glass screen, so that when they explode
white hot tungsten isn't sprayed everywhere starting a fire.  Yes they do sometimes explode
and it is dramatic.

I can attest to the fact that Halogens do explode. We used a number of 600W Halogens as perimeter floods until last year and shattered glass was a regular feature below the floods. Now we use lower power LEDs and get the same quantity of light.
2  Using Arduino / Project Guidance / Re: Too good to be true? on: July 18, 2013, 07:53:09 pm
If you do buy from China, for your own peace of mind get yourself some form of delivery assurance. Do not use ordinary post. I ordered a Cubie board from China that never arrived, 3 months now. So I asked the seller for a courier service and bought another. No problems there.
3  Using Arduino / Project Guidance / Re: Switcher for guitar pedals on: July 12, 2013, 11:06:27 pm
If you just want a signal routing patchboard, the easiest thing is a manual patchboard. The last thing you want in a gig is for the controller to kick the bucket. That's why a manual patchboard will be reliable. Also, if you are thinking of  commercial success in the DIY community, think of the extra audio switching relays this will involve compared to plug in jumper cables.
I'm being the devil's advocate. Not trying to dampen your constructor enthusiasm.
Having built lots of audio circuits as a kid, I know snake oil merchants when I see them and a lot of the DIY audio equipment and kits on sale on the internet are simply rubbish designed by amateurs.
My Behringer distortion pedal died some months after purchase and inspecting the circuit, its Crud. I could have built it myself, just being lazy and bought one. Never again.
4  Using Arduino / Programming Questions / Re: Can't get libraries to load with sketch on: July 12, 2013, 10:29:54 am
Can you move the offending library .h, .c and whatever else is needed, into your user folder and get it to compile ?
I mean, move the files away from the default folders into your personal arduino files folder ?
5  Using Arduino / Programming Questions / Re: Can't get libraries to load with sketch on: July 12, 2013, 12:09:50 am
Are you still in the same situation where importing a library stops compilation or will the ide just not compile at all, using a basic file like say the example in the bare minimum Setup program ?
It's a bit hard trying to decipher your complaint.
6  Using Arduino / Project Guidance / Re: How many batteries are required to power my project on: July 11, 2013, 12:34:31 pm
http://www.neurosky.com/Products/MindWaveMobile.aspx

This has been on the market for a couple of years.
7  Using Arduino / Project Guidance / Re: How many batteries are required to power my project on: July 11, 2013, 11:23:03 am
Heck, it's even better than the mattel glove. I'm impressed.
If you combine it with the brainwave reader..............
8  Using Arduino / Programming Questions / Re: What is Integral data type on: July 11, 2013, 08:35:11 am
Because the function can handle values that are not in the range that can be stored in an int. The actual return type from the function is a long.

The value being converted might be intended to be an int, a long, a byte, a uint8_t, a int16_t, an unsigned long, etc. All are integer types, but only one is an int.

But a LONG is still an integer in the mathematical domain when talking about the set of integers, and so are all the others you have mentioned.
The term "int" is strictly related to the syntax used in the programming language.
When I read the description in the String class initially, I thought it was a translation error.
9  Topics / Science and Measurement / Re: Oscilliscope for beginners on: July 11, 2013, 08:00:34 am
If you can't fix it with a hammer, it must be an electrical problem.

Love the quote. I need to get a Tshirt with that.
10  Using Arduino / Programming Questions / Re: What is Integral data type on: July 10, 2013, 11:51:28 pm
Why not just call it integer in the man page ? Is it an euro-centric expression ?
11  Using Arduino / Project Guidance / Re: How many batteries are required to power my project on: July 10, 2013, 11:23:49 pm
This is becoming an interesting topic for me. I see what you are trying to do. I'm imagining the use of the older sensory glove that used to be available in the '80s, I think. Anyone remember that ? It was used for one of the game console machines.

I came across some other useful points in the forum regarding battery wiring. Isolate your inputs to the circuitry if you can, decoupling [Arduino +Vcc] from the laser driver and servos. Its just good engineering practice.
12  Using Arduino / Programming Questions / What is Integral data type on: July 10, 2013, 11:12:37 pm
Depending how I read this statement from the definition of String class

toInt()
Description

Converts a valid String to an integer. The input string should start with an integral number. If the string contains non-integral numbers, the function will stop performing the conversion.

I am led to believe this means Integer, not Integral number.  What is an integral number anyway ? I apologise for my ignorance if such a object does exist.
13  Using Arduino / Project Guidance / Re: How many batteries are required to power my project on: July 09, 2013, 11:29:19 pm
According to the datasheet, the operating voltage of the servos. Are 4.8-6.0V. I ran one servo with 2 of the batteries I posted (14500 3.7V).
As far as the laser diode drivers go, they are set to output 1.25A of current to the laser diode. I've run these diodes with this driver before and I've needed 2 of these to run one diode. I would assume that the drivers require a voltages of 6V to operate.
That's the thing, I'm trying to figure out how much voltage and current is needed and what batteries could provide such power.
So your guesstimate for the servo looks ok. I assume the laser driver may be a constant current source.
The battery is 900mAh. A quick approximation - if you use two of these in parallel, you would get 3.3V at 1.8Amps for 1 hour theoreticaly.
Now, this is important. I don't know too much about paralleling newer Lithium cells. In the past, I would use forward biased diodes attached to each positive terminal and then serialize the two parallel cells with the rest of the battery. Sounds like a lot of work, does'nt it ?
Using diodes reduces the effective voltage of the cell due to the voltage drop across the diode.
A better way is to serialise 2 cells and then connect a diode to each serialised positive terminal.

Someone else on this forum should verify the safety issues of paralleling without diodes, please.
14  Using Arduino / Programming Questions / Re: How to convert String to unsigned char? on: July 09, 2013, 11:10:40 pm
I think he's specifically referring to using String class than the array
15  Using Arduino / Project Guidance / Re: How many batteries are required to power my project on: July 09, 2013, 10:02:20 pm
If you can get some details on the Servo driving voltage would be good. I've got some here using 18V. Not sure about the one you tagged.
Similarly the driver you want to use for the laser diodes.
A quick look did not give me any information about the required voltage. In these situations I normally use my adjustable bench PSU and figure out the required voltage.
You can use any Lithium pack as long as its output voltage and current is sufficient to drive your circuitry.
Voltage regulator - used to provide a constant voltage supply to your circuitry. This depends on the capacity of your battery pack to keep supplying the required voltage and current for the time you need it to do so.
Do some reading about battery amp-hours. I'm not going to hand this to you on a plate.

What are you trying to construct ? Disco lasers or scaring the unwanted cat ?
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