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General Chat / Re: Balloon flies 51000km and it has just Vanished
« Last post by botcrusher on Today at 02:54:21 AM »
How so? It was launched in Toronto. Assuming the OP isn't an american who went to canada to launch, i don't see how he could get in trouble with norad when asking about a balloon.

NOrad = North American. It's staffed by US and Canadian forces.

Yeah, but let's be real. who's got nukes, and who is worried about being nuked. not canada XD

Also, if they shot it down for kicks (if they did shoot it down) that makes more sense because you'd have to be quite drunk to mistake a balloon for an ICBM!

-Far, far too slow
-Radar would basically tell them it's a party balloon / something the size of them
-They don't shoot down birds, do they?

Anyways, this mystery will probably be never solved.
Should totally put a backup battery with the sole purpose to flash an led periodically and perhaps try a few powerful bursts of data to locate it upon landing.
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Microcontrollers & FPGAs / Re: ATMEGA328 adc , registors
« Last post by PeterFW on Today at 02:52:54 AM »
what have I done wrong ?

You do not give the µC time to finish the conversion, check the ADSC bit in the ADCSRA register wich gets cleared after the conversion is finished in single conversion mode, if you do not use free running:

while(ADCSRA & (1<<ADSC));

Alternatively, flash the arduino bootloader on the chip and use the Arduino IDE wich spares a lot of trouble and grief at the expense of code size. 
3
Are you sure you amplifier circuit(s) provide a suitable path for the amplifiers bias currents to escape?  Op-amps with outputs that chase off to their rails often indicates a mis-matched (or completely un-handled) input impedance issue!

I'll throw in the filter circuit as I have it on my boards.  I didn't know that input impedance really mattered with regard to Op amps because they already have a virtually infinite input impedance?  I was wondering if adding a resistor from the output to ground would be necessary to allow the output current to go somewhere, but when I switched the program to only sample at the one input actually connected to a sensor it all seemed to work find and didn't drift at all.
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Test Equipment / Re: DS1054Z FFT Example
« Last post by Loboscope on Today at 02:41:54 AM »
Indeed, I can fully confirm @_Wim_ that nowadays nearly all reasonably good audio-interfaces will work more than satisfying for audio measurements. With 192 KHz samplerate, today you should go flat from at least 10 Hz to 95 KHz.
I use the (professional) analysis-software "hpw-works" [http://hpw-works.com/] together with several RME-Intefaces. RME is generally known to deliver a superior quality (and not to be the cheapest manufacturer). With equipment like this you can really make absolutely reliable and professional measurements and trustworthy tests of your audio equipment.

Greetings, Jürgen
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Test Equipment / Re: EIP 575 microwave counter
« Last post by joeqsmith on Today at 02:40:49 AM »
Looks good.  Should provide you many years of service.   
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Repair / Re: Studio Strobe Light repair
« Last post by RadoK on Today at 02:40:08 AM »
Issue found and resolved! The strobe light works now. Even with stronger xenon tube.

Murphy's law again. Before, I was not measuring voltage directly at the thyristor anode but one resistor away where the main caps votage was entering the triggering board. Just because it was much easier accessible for measurement. I assumed that two thrids of the voltage should be at thyristor. Wrong.
Today I was following OiD's suggestion to use relay instead of the thyristor (to short it). Once I had cables soldered it was easy to measure real voltage at the thyristor. And it was 0V. The resistor going to the anode was open. No sign of demade but it was faulty. Quite surprising because it was half mega 1W resistor used to limit charge current for the triggering capacitor. Voltage 350V max. It is less than 1 mA charging current.

Thank you all for suggestions. I was ready to give up last weekend but your support kept me trying.
Rado
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Boy, be user to test for and label the proper phasing for all those windings, both parallel primary and series secondary. In phase adds, out of phase subtracts.

The FET configuration wouldn't be right for a forward...
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Repair / Re: Keithley 2601
« Last post by plesa on Today at 02:29:09 AM »
What can you help with repair is Keithley 236/237 service manual.
https://doc.xdevs.com/doc/Keithley/236_237_238/236_902_01D.pdf
I'm just using it for Keithley 2400 repair. On page 89 / chapter 4 Theory of operation are simplified schematic and lot of magic explained.
Or alternative
http://exodus.poly.edu/~kurt/manuals/manuals/Keithley/KEI%20238%20Service.pdf
on page 66 with minor differences.
Or you give up and send unit to Keithley for board swap?
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This is the beginners section of the forum.
IMHO the reason for designing a circuit like that is so that we can get a HIGH GAIN.
It's obvious that a load would be connected to the circuit,why else would it be built.
Lots of this type circuitry would be inside op amps to achieve high gain.
So whats the point of ranting on about considering it as a current source just because it's Hi Z.
We want to use it's hi gain as a VOLTAGE amplifier.
We should try and keep things simple so beginners gain an understanding of why circuit
configurations have evolved to perform a function.

3DB |O

Exactly.  People use an active load with a high impedance to achieve a high voltage gain.

You can look at the input circuit of the venerable LM741.  This circuit has been used for fourty years.  It is a textbook circuit.  They describe how it has high voltage gain, not that it has a current source output.

It was in my college textbook 35 years ago (we studied the earlier edition):
http://www.amazon.com/Analysis-Design-Analog-Integrated-Circuits/dp/0470245999/ref=sr_1_3?s=books&ie=UTF8&qid=1462032712&sr=1-3&keywords=linear+integrated+circuit+design

Every real amplifier circuit has an input impedance and an output impedance, and the gain depends on source impedance and load impedance.

I have no problem with Performa01s explanation apart from the wording that was a little confusing and he clarified that in his later post.  I thought it helpful to offer another explanation from Wikipedia.  It says basically the same thing, I agree. :clap:
10
Who is going to contact FeelTech about the power issue?
See in the thread above for contact details of the company FeelTech.

I don't have all the details of the power issue at hand, and believe it would be better if the OP of the power issue takes the initiative.

I just sent an email to Carl at Feeltech (their sales manager for foreign business) describing the problem and asking them to suggest a fix.  At present, a 2-pin polarized AC replacement connector or 3-pin AC connector with DC ground connected to earth/safety-ground seems like the best solution.  It would be nice if they could identify a connector that fits the case without modification.

Did you receive any feedback from FeelTech in the mean time?

Maybe you could send a reminder, and also point their sales manager to this thread in particular.

FeelTech might get their act together if they realize that this thread, for which I proudly am the OP :),
has been viewed more than 28.000 times :)
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