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Brundizzle B (verified by your mother)
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+Yuji Naka +Michael Kukat 

Any suggestions for me?  I would like to make a bench power supply.
I have this transformer that transform 220V AC to about 10V AC.  with  rectifier bridge I make DC from it...    I use a 2200 uF capacitor to get a steady voltage.   the LED and resistor are just there to indicate it's on and to discharge the capacitor when it's off.   I then feed it into a voltage regulator (LM317T) to be able to fine tune the voltage.

I am actually thinking of connecting a couple voltage regulators in parallel (connection to point A en B) to provide me with 1V, 3V, 6V and 9V.    I also think I should build a current limiter in there. (maybe the easiest way would be a simple fuse) 

What I am still struggling with is the value of the smoothing capacitor.  2200uF seems to work...  but I am not sure if this is the best choice. I found a general formula for the value of a smoothing capacitor:  C = I * t / dV   (where t  time and dV is the voltage drop to be compensated by the capacitor.     In my case it is easy...  mains come at 50Hz and the 10V AC as well, so the gap between the peaks is 0.01 second.  Voltage drop seems to be around 12 V when I measure it...   However, I have no clue what the current is.  I tried to measure it using a crappy multimeter (used the 10A socket) and the meter read 19.5  ...  I suppose the thing would fuse over 10A ...  and it didnt.. so maybe it's 2A?   Also not sure if i measured it correctly..basically shortened it with the meter.

anyway...  any suggestions are welcome! :) 
 
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Brundizzle B (verified by your mother)'s profile photoTesla Explorer's profile photoMichael Kukat's profile photomatt derpson's profile photo
25 comments
 
just build a flyback driver and destroy alll the things
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+Michael Kukat and others ... anyone knows anything about the current in an antenna? (transmitting, not receiving) I am struggling to create a conceptual framework in my mind to understand how it works....

thus far i visualise it as electrons having different density in the antenna. This travels more or less like a wave in a spring (http://physics.appstate.edu/laboratory/quick-guides/waves-slinky) .... this then causes electromagnetic fields etc etc.


does this make any sense??? or am i completely off???
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Brundizzle B (verified by your mother)'s profile photoMichael Kukat's profile photo
7 comments
 
Definitely, it can only be the "ground plane", your roof. With just 1m, this sounds like 1/8 lambda. I think i have a magnet antenna of this length somewhere, i also had 1/4 lambdas in use back then, mounted on the trunk. 2.75m or so :)
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no safety cord whatsoever.. impressive 
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This guy is taking apart a Nike Fuel Band.. at 21:40 he says something that was EXACTLY my thought when i was watching the clip!
https://www.youtube.com/watch?v=7xdajSS_cOU&feature=youtu.be&t=21m40s
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Brundizzle B (verified by your mother)'s profile photoMiss Oxy's profile photo
3 comments
 
D;
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#CoC ... THIS is how you defend your loot! 
1
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A fundamental list of antenna theory concepts, an antenna basics menu is given here. Topics include directivity, polarization, bandwidth, impedance, frequency bands, all things necessary for an understanding of antenna theory, antenna basics and antenna fundamentals.
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kinda surprised my Galaxy S5 picked up GPS signal through the airplane window
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Andreas Dorfer's profile photo
 
these GNS become better every year.
(but i still do not find any affordable source for ublox NEO M8U (U!) - And no, i will not pay 20€ for shipping)
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To all the Muslim plussies
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Left: Munich Airport App.. showing flight LH2304 has been delayed and will depart 14:00 (this message has been up for couple of hours now)

Right: Schiphol Airport App... fuck you Munich.. find a way to travel back in time!

You would expect they would be able to get the correct ETA on the app! 
(i know for a fact that the flight did not depart) 
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John Lewis's profile photoBrundizzle B (verified by your mother)'s profile photo
2 comments
 
it wasn't me on the plane 
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