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General Chat / Re: What did you buy today? Post your latest purchase!
« Last post by nanofrog on Today at 12:07:59 am »
Wouldn't take much to make it look near new again.  :)
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Make an algorithm which can losslessly reduce the size of any file by JUST ONE BYTE and you'll become a trillionaire.
Yep, then apply it recursively.....

Regards, Dan.
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There must be a serial validation algorithm...
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Hi there,

I've been googling for AGC circuits, or perhaps, "constant volume" circuits.  Input comes from a guitar so will be ~800mV p-p, dropping to ~30mV and I would like to get a constant 1V out from this, or at least a significantly reduced dynamic range, say 0.5V to 1V.

It is for a DIY strobe tuner that I've been meaning to build for a long time, so the signal won't be heard or further amplified for sound, so distortion isn't really a problem.  It will be used to drive LED's via a V/I converter. Some filtering would be required as I'm hoping to get mostly the fundamental and perhaps the second harmonic (used for setting intonation on guitars), but this can be done before the AGC, or after.

I'm thinking a low gain preamp to bring the signal up from the @30mV minimum to say 100mV.  This brings the range to ~100mV to ~2500mV.  I've mostly come across circuits using LED/LDR combos (I can make my own with hollow standoffs and heat-shrink) or JFET's.   I only have some N channel JFETs in stock, where-as most AGC's seem to use P-channel as a "variable attenuator".  So before I start tinkering and make an order I thought I'd post here to see if anyone has something they've used before.

Cheers!
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I don't know too much about these things, but when it comes to temperature regulation and PID loops, wouldn't more resolution/precision offer superior control, irregardless of the display?  Could the ADC resolution be primary there to drive control?  Maybe this is obvious..
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Microcontrollers & FPGAs / Re: Microchip XC8 (v2.00) Compiler
« Last post by HB9EVI on Yesterday at 11:58:10 pm »
This is actually the pain with the Microchip compilers. Instead of focusing on their hardware business, they have to deal with shabby software they were actually not even able to develop on their own; they had to buy it and integrate the whole company in theirs. That was for me the reason to leave the Pics behind me very fast and use just the AVR platform as 8bit mcus.

short: the binaries from the free compiler is just garbage; it's completly bloated.
and to say it clearly: because of the banking, the PIC16F are barely useable for high language programming while at the same time the pic asm is a total pain to use. Although the PIC18 are quite neat mcus
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Beginners / Am I misunderstanding how Buck converters function?
« Last post by cbc02009 on Yesterday at 11:55:02 pm »
So I built a breadboard prototype of a buck converter I will be using as part of a larger project, but I'm not sure if the results I'm getting make sense, and I was hoping someone could sanity check for me, as the buck converter is stepping down the voltage just fine, but doesn't seem to be stepping up the current.

The converter schematic is attached below. Both the VCC and the V_in are coming from a USB 5V supply. The PWM is supplied by an MCU.

I think it has something to do with the load, since it's just a plain resistor, and I = V/R, so the load essentially dictates the current coming out of the converter. I get that the buck converter is useful because the output voltage will always be duty_cycle*V_in, regardless of the load (within reason), but I feel like either I made a mistake in the design for the efficiency to be so low, or there's just something fundamental that I'm missing.

LTspice simulations match what I'm getting for results, as well, which makes me think I'm just not getting something. Apologies if it's something blatantly obvious that I'm missing.
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Repair / Re: Need help to identify a diode. Not SMD.
« Last post by HB9EVI on Yesterday at 11:52:33 pm »
It's fun up just to the point, where failing old brand devices block the everydays work pile down. As soon as you repair the scope or the spa more often than getting forward on your regular task, it just sucks; this is why I sold all those old nice beauties and got new ones. It took a while to get used to the imagination working with a DSO instead of a crt scope, but in the meantime, I wouldn't like to miss it.
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While at heart I agree with the sentiment, (And besides Bob was awesome) there really are things for which the easy way is digital.

If you were designing a LT style controller chip you would probably go analog, but in the absence of such an all in one solution being available throwing a micro at it is usually the quick and low BOM cost way to market.

I found myself using a little 8 pin micro in place of a 556 dual 555 timer the other day, it was cheaper and more compact.

Regards, Dan.
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Manufacturing & Assembly / Re: My first PACE ADS200 victim
« Last post by DC1MC on Yesterday at 11:51:57 pm »
To solder on Aluminium, do it under a big drop of motor oil. No fancy flux required.  :-+
Probably cooking oil will work too. The idea is to block the Oxygen from air to come in contact with the Al and form oxides at the soldering point. Oil can keep the Oxygen away.

NOTE: Cover the soldering tip in Al foil before soldering, or else the tip will never be the same.

This guy solders, listen to him :-+, when I've first witnessed this trick of an old ham that was making cases, my eyes were almost popping out, I've never thought it's possible. At the time there were no Metacals and hi-tech stuff, just a big ass iron and some clear mineral oil (don't use the aditiveated motor oil, it will make a bad surface).

   Cheers,
   DC1MC
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