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871  Using Arduino / General Electronics / Re: How to TTL a laser? on: October 25, 2013, 07:21:38 pm
First laser was 1995 for me, and my last powerful one was a 200mw greenie,  burnt bags lit matches, then after almost losing my right eye,  i tried to increase its power and killed it $150 put me off lasers for a while, switched to high powered flashlights . .

I do love uv lasers though and green glow in the dark paper, draw by light.
872  Using Arduino / General Electronics / 7hc595 Voltage Out. on: October 24, 2013, 10:38:35 pm
Having a look at the 7hc595 datasheet and I was scratching my head why at 100 ohms on the base, I was still only getting a total a 1.2 amps, then i realized it's USB voltage, so it's probably closer to 3.8v (i'll check in a few minutes) but anyway I plan on increasing the voltage to 5.8v to drive the transistor harder..

6v a little excessive to do all the time?
873  Using Arduino / General Electronics / Re: 220 uf 16v caps... on: October 24, 2013, 10:08:00 pm
https://www.google.com.au/search?output=search&sclient=psy-ab&q=electrolytic+capacitor+reverse+polarity&oq=electrolytic+capacitor+revr&gs_l=hp.3.0.0i22i30l3.1296.15425.1.17271.18.18.0.0.0.0.422.5404.2-12j5j1.18.0....0...1c.1.29.hp..0.18.5399.-wxfXlz2el4&bav=on.2,or.r_cp.r_qf.&bvm=bv.55123115%2Cd.aGc%2Cpv.xjs.s.en_US.Ag3CcnQBszM.O&biw=1047&bih=858&dpr=1&ech=1&psi=ReFpUrL1LKSjigftwIGoBA.1382670669364.3&emsg=NCSR&noj=1&ei=ReFpUrL1LKSjigftwIGoBA

always believed it to not be possible to reverse charge all electrolytic caps.....
874  Using Arduino / Programming Questions / Re: password checker 'Brute Force' on: October 24, 2013, 09:25:29 pm
Add the correct delay, and you can see how much time it would actually take to hack your password.
As for my password, without a delay : 212 microseconds.
Now, with a delay of only 5ms : 1901596(!) microseconds.


"my password" 212 microseconds how???  sounds wayyyyy to fast to crack your password of that length even 212 seconds sounds too quick
875  Using Arduino / General Electronics / Re: can I read these pulses w/o voltage divider using Arduino Uno? on: October 24, 2013, 07:12:01 pm
I want to count pulses with an Arduino Uno.  My pulses are nominally 5V but the actual signal fluctuates between 9V and 3V for about 2 Micro seconds before settling in to 5V for another 13 micro seconds.  Can I read these pulses directly through the digital pins or should I use something like a voltage divider?  Using a voltage divider (pair of resistors) that gets the peak voltage less than or equal to 5V results in the overall voltage becoming too low to count consistently (I count 50% less pulses per minute using the voltage divider).  The frequency of the pulses I'm measuring is about 1 per second. 

Maybe the bouncing between 9V and 3V for a couple of microseconds won't hurt the Arduino board (maybe that's normal for the beginning of a 5V signal)    But I wanted to check before I count the unattenuated signals for any length of time.

If there's an alternative to a voltage divider, please mention that as well.

how much current? - I'm thinking 5v1 zener diodes to just be on the safe side...
876  Using Arduino / General Electronics / Re: Killing my arduino on: October 24, 2013, 07:10:07 pm
   or did I just do something really dumb

Is the correct answer....  the ONLY  time you can safely (up to the mm's fuse rating) is with low power, small solar panel, peltier, dc motors (when hand cranked), for example a 3v 20ma solar panel, you'll read 20ma with good sunlight....

otherwise you measure in SERIES, or you'll do what you did... shorted out the power supply.
877  Community / Bar Sport / Re: Unfriendly Geek Clique/Arduino hostility on sites like StackExchange on: October 24, 2013, 07:05:28 pm
When part of the minority expect it, when part of majority expect it harder lol
878  Using Arduino / Programming Questions / Re: password checker 'Brute Force' on: October 24, 2013, 07:00:15 pm
Unless you're expecting somebody to use an Arduino to crack your password (which would be a weird thing for them to do), is there any reason to do this on an Arduino? The algorithm would be easier and quicker to develop on a PC and would run massively faster.

Add the correct delay, and you can see how much time it would actually take to hack your password.
As for my password, without a delay : 212 microseconds.
Now, with a delay of only 5ms : 1901596(!) microseconds.

I think you need a longer password.....
879  Using Arduino / General Electronics / 220 uf 16v caps... on: October 24, 2013, 04:32:03 am
http://www.ebay.com/itm/BRAND-NEW-20pcs-NIPPON-SME-BP-Bi-Polar-16V220UF-16v-85-C-10X12-5mm-CAPACITOR-/271092338444?pt=LH_DefaultDomain_0&hash=item3f1e5ccf0c


But wait... are these not electrolytic?!
880  Using Arduino / Motors, Mechanics, and Power / Re: Best way to control (on/off) a 12v power supply? on: October 23, 2013, 09:35:56 pm
Although prices are coming down fast for fets check out this..

http://www.ebay.com.au/itm/10A-400V-N-Channel-Power-MOSFET-Fast-Switching-IRF740-/150975673259?pt=AU_B_I_Electrical_Test_Equipment&hash=item2326d9f3ab

881  Using Arduino / Motors, Mechanics, and Power / Re: Best way to control (on/off) a 12v power supply? on: October 23, 2013, 09:34:19 pm
With such a small load, you'd get away with something like a Tip31 power transistor (and place a diode in for any inductive kickback ) and a 1k resistor to base.

882  Using Arduino / General Electronics / Re: Extend Pulse from Op-Amp/Photodiode combo? on: October 23, 2013, 09:01:22 pm
I forgot to put "s" on the end of "transistor"

883  Using Arduino / General Electronics / Re: Extend Pulse from Op-Amp/Photodiode combo? on: October 23, 2013, 07:48:27 pm
I'm curious about c1...

I thought it's function was to be a high pass filter? Is it needed?

2ndly, i want to recreate this circuit but using a transistor instead of an op-amp.

884  Using Arduino / General Electronics / Re: Transistors - what is the collector/emitter voltage drop? on: October 23, 2013, 07:39:37 pm
Arduino's native libraries is not what i'd call huge, there should not be an excuse to miss out any commonly used functions.
885  Using Arduino / General Electronics / Re: Still learning resistors on: October 23, 2013, 07:34:31 pm
There is only one issue, why does the calculator tell me I will get 7v if I apply 350 ohm resistor to 20ma?

See my previous answer: Voltage drives current.

Your calculator is not saying you will get 7V. It is saying you have to supply 7V across the resistor if you want 20mA to flow.

In hindsight, someone should have explained that sooner lol
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