Electronics Tutorial - Building a Low noise signal amplifier Part 1/3 - Documentation
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- čas přidán 8. 08. 2024
- #62 In this electronics tutorial mini-series I set out to build a low noise signal amplifier to measure very small signals that are usually below the generic oscilloscopes noise floor.
This time I look at the fundamental concepts behind measuring very small signals - where this is used and how a circuit needs to look like to achieve this. I have a look at multiple Application Notes to see what others have done and see what the essence of such a circuit is.
Application Notes:
www.analog.com/media/en/techn...
www.analog.com/media/en/techn...
www.analog.com/media/en/techn...
Also in this miniseries:
Ep1: • Electronics Tutorial -...
Ep2: • Electronics Tutorial -...
Ep3: • Electronics Tutorial -...
More info on the topic:
• 775 Nanovolt Noise Mea...
• Minimizing Switching R...
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Music:
The Builder by Kevin MacLeod incompetech.com
Creative Commons - Attribution 3.0 Unported - CC BY 3.0
Free Download / Stream: bit.ly/_the-builder
Music promoted by Audio Library • The Builder - Kevin Ma... - Věda a technologie
Thanks for showing this circuit and giving a Very Good discussion of it, Jim Williams would liked the discussion!
I built the first of these boxes and designed the PC Boards for Jim Williams, the one you see in these pictures, Jim Williams really put a lot of effort in this design, this design was the Evolution of Jim's experience. This was the recurring theme of Jim Williams Design, one of his favorite design evolution was the design and the redesign of Frequency to Voltage converters, Jim and Bob Pease went back and forth with these designs!
In this design some parts were hand selected, matching Pair of FETs etc.
Many of Jim's App notes should be studied and used as real World " Design Process Examples " !
In particular AN 65 and AN 47, Backlight circuits and High speed design. These will be relevant forever!
I keep all of the Hand drawn, Work in Process, Schematics with all of the design notes and comments along the way. I still have the CAD Files to make PCBs for this design.
Great video, but here are a few details you are probably aware of, but didn't include in the video:
1) Jim Williams, who wrote the first two ap notes is generally considered the greatest analog engineer of all times. He was one of the founders of Linear Technology and worked on the bench almost to the day he died.
2) At frequencies below 100 kHz, steel is a much better shielding material than copper. Tin coated steel is ideal because the tin allows for use of a press fit lid with no leakage. This type of tinned steel enclosure (paint cans and cookie tins) aren't 'good enough'. They are actually as good as it gets unless you are willing to spend a lot more money for exotic materials like mumetal. And all that from something that most people are throwing out on a regular occasion.
3) Ceramic capacitors come in three different types; Type 0 (CG0 or NP0), Type 1 (X5R, X7R, X8R), or Type 2 (everything else). Type 1 and Type 2 are microphonic and also change capacitance based on DC bias voltage and are thus unsuitable for signal path use. Type 0 capacitors are extremely non-microphonic and are actually the best choice if you only need a small value (say less than 0.1uF). Kemet had a paper that showed this by comparison with aluminum electrolytic, film and tantalum capacitors, but I can't find it right now...
Thanks for this info. Gonna look up Jim Williams now. Also it's not intuitive to me why steel is a better low frequency shield. Is it the fact that it's ferromagnetic or is less conductive?
@@seancsnm Maybe his other video can show you: czcams.com/video/2U1o66bs_Qg/video.html
He is a superman of LTSpice!
Thank you. I really enjoy both your expertise and your sense of humor.
Wow what a small world we live in. I went to CZcams to get a break from studying LT's an83 and an124 and this is the first video that comes up in my search!
Great, thanks for the tutorial and generous calm explanation of the circuit application.
I finally built and used this circuit. It performed as expected and I am now more knowledgeable, thanks to FesZ.
A little note, one instrument that Jim Williams liked a lot was Lock-In Amplifiers! An instrument that can dig out ultra low level signals Buried in Many Volts of Noise, Like retrieving insanely low level signals from some well known space Probes that have left our Solar System!
Could you do a follow up on what type of cookie boxes work best for different applications? I’m especially interested in when not to use Christmas theme boxes, as I fear the added cheer will cause interference.
I was looking trough some old Popular Electronics magazines, and there is one in which they recommend using a coffee can as a chassis for building electronic projects. From noise point of view, I think that is even worse than the Christmas theme... the circuit will end up being all restless and fussy
Awesome !! All of your video are One of a kind video, keep going all the best. Look forward for more video like this 👍💪
I love this Cookies Tecknology appnotes 😃
Learning alot from you
great explanation
You deserve more subscribers
Excellent! Moving right on to part 2...
The cookie tin progression is very funny. That HP voltmeter is pretty special though - I recall it has something like 20MHz of bandwidth on AC. It is more like a power meter voltmeter hybrid. I can see why they would still use one.
Just because a piece of equipment is old doesn't mean its obsolete. I think that as long as you know the exact specifications and limitations you can use old equipment very successfully even when "newer" stuff is available.
Coming back to the HP voltmeter, I think its really nice that you can finds its full schematic in the service manual - bee.mif.pg.gda.pl/ciasteczkowypotwor/HP/3400A.pdf
Looking trough it, I think its quite amazing they are using a vacuum tube to ensure minimal input impedance.
Thanks so much!
Thank you for your efforts, helps me to learn a lot!
Hello Tibor! I'm happy you are enjoying the content! Let me know if there is anything particular you would be interested in.
Great video man
I wish I could subscribe to your channel for ten times!
Great video, thanks Fesz
Your videos are awesome! Keep it up please, in the name of the community!
Thanks FesZ for this nice video!!
When I saw the old scope and the cookie tin I knew that app note had to have been written by Jim Williams :-)
Your expression at 13:00 made me laugh so hard!! xD Love it!
you are amazing gars!
bon courage!
Hi can you make video on how one port and two port network synthesis applied practically on designing ckts like filters and amplifiers, thank you.
ThankYou
Using many cans may not help you if they are not magnetic shielded. Also at the input and output connector if the shield is not connected properly it will ruin your isolation.
I need that ic but operating at 1mhz instead of 100khz.
Hello...
I'm designing a 20db gain lna for rf signals using mmbr951 rf transistor but I have some problems my output signal can not be more than 1v p-p on 50ohm load and more than 1v p-p makes some clipping and distortion in my signal what I should to do for more voltages?
Is there a component model in LTspice of the cookie tin?
LTspice by default models its circuits as being in the ideal cookie tin wherein there is 0 EMI.
@@seancsnm :-/
Jim Williams heritage
To have a cookie box, ok. Well, xmas one is a bit less easy, but understandable, doable..
Suppose, just by chance I have couple of sheets of 2mm 2oz copper FR4 (:
But to have a mu-metal box casually laying around, I think I haven't grown my grey beard enough yet.
All of a sudden, I have this huge craving for some Christmas tin cookies 🤔
You could probably buy a secondhand B&K microphone amplifier quite cheaply these days. BITD this would have been good enough to measure audio circuits with output noise around 1-2 uV (with the right biscuit tin of course ;-) )
well there goes the diet, Oh well its all in the name of science.
I think I'll have to cancel the idea of looking at the effectiveness of making an emi shield from chocolate tin foil and chips bags...
please help me to build Low noise signal amplifier with frequency rage 100 to 1200 MHZ wi minimum 20db gain please..
word of caution for those generating noise for hobby stuff, double check your local band emission regulations. for example, if you are in the US and you accidentally leak L-band beyond a certain (fairly small) limit, you will be subject to massive fines over $300,000. this may seem obvious, but my real point is how little noise transmission it takes to break the regulations in the US. i'm talking basically anything over noise floor and you can get jammed up. this is kind of a case of "if you don't get caught, its not illegal" in the sense that if you leak noise at such a remote location that it doesn't get received, but its something to consider. You can use RF isolators if you really want to make some noise and stay legal. you could safely generate up to 30 dBm of noise with some good isolators lol
Noise generation is low power so if even it leaks out, it is blocked by your house's walls.
SMPS are NOT noisier than linear. There are SMPS that are quieter. In particular many of the MeanWell LED supplies are known to be very quiet. But you have to make sure a) it's loaded properly to keep it out of "hiccup" mode and b) you don't load it with too much capacitance to keep it out of protection mode and c) use little bit of filtering take out high frequency switching noise. I like using a capacitance multiplier because it solves b and c in one pass. ACDC or DCDC doesn't matter. Most of the MeanWell ones are great. A linear supply is almost guaranteed to have some mains noise where as a good MeanWell SMPS properly used will have no mains and be completely silent. Lot's of pro audio DIY people are using them now.