Perfect! Well thought out presentation and simple, understandable walk-through of the design process broken p into three easily digestible segments. Every tech person should make videos this way.
I saw this approach being used in other projects. The one that comes to mind is EEVblogs uCurrent project ( www.eevblog.com/projects/ucurrent/ ). This project also highlights another advantage - if you buy the PCB from some manufacturer, you can use the silk screen layer to mark the various inputs/output, add a logo or something or add any drawings or things necessary - this will make the device look far more professional than if you write things by hand.
I noticed this in approach in various products - even commercial ones. Its quite nice that you can chose the PCB color (the solder mask) to be the same as the rest of your box - so its not obvious that its a PCB. Also you can add text in the form of the silk screen layer - to describe connector and switch functionalities.
Actually, aluminum will attenuate the E-field while the ferro/iron attenuates the H-field component, so the best solution is to use a galvanically combined sheet of Fe and Al for the enclosure. This is how they build the EM silent TEMPEST chambers against SIGINT leakages.
Hello electrotechnica I googled it yes it's true what you're saying but aluminum is a bad shield for EMI on low frequency the amplifier in the video is designed to measure low frequency noise.
Hello, great video! I was wondering if you consider the time scale on the oscilloscope when you take your rms measurements. Since the rms noise on the scope is usually the integration of the signal over the sample memory period, the reading surely varies with the time division you are using, no? I understand its a rough approximation but i find this rather interesting since it can potentially influence the readings by a non negligeable amount. what do you think?
The scope must also have some BW limiting in place and the number of samples and rate must match that limit. Having fewer samples will cause the noise to mix down and increase the displayed noise floor.
If you AC coupled the amplifier, why didn't you add a capacitor in series with the feedback resistor at (-) input to ground? You don't want to amplify the op-amp's own offset, right?
Hello! From what I could notice the LM833 does make a bit of noise, but it's canceled out by the other op-amps high PSRR (power supply rejection ratio). From what I remember, by swapping the LM833 with another AD8676 I did not notice a major difference; in general it will be best to have all op-amps really low noise, but the only one that is truly critical is the first amplifying stage.
Of course not! I left a link to it in the description. One condition though, if you build it, let me know how it works, I'm really curious what your results are.
In your schematic, the trimmer appears to have the two ends of the resistive element tied together and the wiper tied to ground. Is this intentional or is this an error? Often you see potentiometers connected as rheostats - i.e. a two-terminal variable resistor. One end of the resistive element is usually tied to the wiper rather than left unconnected. What is the typical resistance set point of the trimmer?
I think I needed an 100R resistor (ideally) and the only trimmer I had at my disposal was 1Kohm; The ends where interconnected intentionally to try to make it easier to adjust the value. With 1K connected the usual way the 100R point is somewhere around 10%; but with the ends interconnected, the same resistance can be obtained somewhere around 20%; If you have a 200R trimmer, than you can of course connect it the normal way
In your schematic, you have the LM833 powered by a 9V battery. The LM833 datasheet specifies a recommended operating condition of VCC,min = +/-5V. Did you use this part intentionally, knowing somehow that it will operate at voltages as low as +/-3.9V or is this a design error?
I can't say for sure what was my logic when I made the circuit; but the supply voltage seems to be manufacturer depended - OnSemiconductor and TexasInstruments LM833 require a +/-5V whereas ST has a minimum of 2.5+/- (see table 2 www.st.com/resource/en/datasheet/lm833.pdf ) I guess I was using the ST branded component so 9V was sufficient
@@FesZElectronics - Good job. I didn’t even check the ST datasheet. I just assumed all LM833’s would have the same Vcc range. Looks like I’ll be buying the ST version. Thanks for the great videos and helpful information!
Sure , but nobody mention about fact that the biggest part of noise is always coming form outside. So internal op amp noise is not an issue at all compare to enviroment. For example check your noise form guitar effects which you already built. Please prepare movie how to get rid of this. Compensation ect.
I'm curious, how much noise is added by your centering op-amp. Since 78xx regulators are common devices, I wonder if something can be done to reduce their noise. You used a battery for its low noise contribution. Could a linear regulator be used? The op-amp is supposed to be insensitive to supply noise. So how much would get through?
> Since 78xx regulators are common devices, I wonder if something can be done to reduce their noise. Noise is measured over bandwidth, so reducing the bandwidth over which the output acts, reduces the measured noise. This means more filtering at the output reduces measured noise. >You used a battery for its low noise contribution. Could a linear regulator be used? As seen in the video linear regulators insert noise into the supply lines. This can couple directly into the measured signal (see next point). They can be used, but batteries are a convenient way to get very low noise, plus you dont need to be worried about EMI/RF coupling from outside sources. >The op-amp is supposed to be insensitive to supply noise. So how much would get through? If you look in the datasheet of the opamp, it usually has a quoted 'power supply rejection ratio' or PSRR. Worst case for this opamp is 106dB from +-5 to +-15V. this is the change of input offset voltage compared to PSU voltage. You can do the calculations yourself how much that would be for a noise signal of a certain bandwidth. It is important to note, that the PSRR is usually denoted for a limited frequency band, but it is actually frequency dependent!! If you look further in the datasheet, at fig 21, you can see its frequency dependency and note that it quickly drops off at higher frequencies. Thus the type of noise signal is important to be considered too.
Hello, in your case did the metal enclosures make any difference? And did you earth ground the enclosures? In that case wouldnt there be ground loops since the scope is also earth grounded?
Hello. To be honest, I did not really notice a difference but that might be because I was working in an area that is quite EMI quiet. If there was more noise in the area than the difference might have been more noticeable. Regarding ground, connecting each circuit element to earth ground but also in between will of course create loops as you pointed out which is not a good thing. In my case the grounding was EG to oscilloscope; oscilloscope to Amplifier; Amplifier to enclosure.
I'm not sure what you are referring to... The symbols without a clear name are the RF connectors on the input and output - these have 4 ground pins; and I also have in top left corner a switch that also has 2 ground fixation pins.
Sir, can I use this command in LTSPICE for resistors? {mc(10k tc=0.0001,tol}} . As I want to do monte carlo analysis at different temperature. Is there any other alternative. Please guide me as soon as possible.
Hello Irsa. The monte-carlo command will only work on a single parameter - it doesn't care what component you are using. To use the "tc" attribute, you need to use resistors, but the mc command doesn't know this. So to use both mc and tc, the syntax would be " {mc(10k,tol)} tc=0.0001 - this way the temperature coefficient is applied on the monte carlo final value. Let me know if this works out.
@@FesZElectronics I have another question. Can we introduce faults in components in LTSPICE, like we can do in MULTISIM. zone.ni.com/reference/en-XX/help/375482B-01/multisim/settingplacedcomponentsfaults/#wp245032 Please guide me. MULTISIM provides option for these kinds of faults for every places components. Is there a way to introduce faults in components in LTSPICE?
What the hell! This is the biggest voltage regulator! Not just any regulator. It is RUSSIAN! One which behaves as an integrated circuit with 'null adjust'. It is an integrated circuit anyway but the small one is commonly not considered as an integrated circuit due to its common usage as a voltage regulator.
Also for me: "Great video, the content is high quality. Please continue this serie, it is very interressting".
Great video, the content is high quality. Please continue this serie, it is very interressting.
Perfect! Well thought out presentation and simple, understandable walk-through of the design process broken p into three easily digestible segments. Every tech person should make videos this way.
The idea not to use the cover but to skew the PCB to the rest is genius.
For years I struggled to connect the PCB to the Coax Connectors. Duuh
I saw this approach being used in other projects. The one that comes to mind is EEVblogs uCurrent project ( www.eevblog.com/projects/ucurrent/ ). This project also highlights another advantage - if you buy the PCB from some manufacturer, you can use the silk screen layer to mark the various inputs/output, add a logo or something or add any drawings or things necessary - this will make the device look far more professional than if you write things by hand.
can't wait to build this little circuit!
thanks a lot for your videos
Let me know how it turns out! Cheers!
you have an extraordinary channel. Nice to found it!
This serie is amazing. Thank you for your effort.
Having the PCB double as a front panel is a nice touch.
I noticed this in approach in various products - even commercial ones. Its quite nice that you can chose the PCB color (the solder mask) to be the same as the rest of your box - so its not obvious that its a PCB. Also you can add text in the form of the silk screen layer - to describe connector and switch functionalities.
Well presented set of 3 videos. Maybe make an improved version where the active filters are after a lower noise front end for episode 4?
Excellent 👍
Particularly the cookie box selection 🤣
Actually, aluminum will attenuate the E-field while the ferro/iron attenuates the H-field component, so the best solution is to use a galvanically combined sheet of Fe and Al for the enclosure. This is how they build the EM silent TEMPEST chambers against SIGINT leakages.
Aluminum cases are very inexpensive and thicker than metalized plastic.
Maybe there is cast iron?
In my experience these Al boxes do the trick.
Hello electrotechnica I googled it yes it's true what you're saying but aluminum is a bad shield for EMI on low frequency the amplifier in the video is designed to measure low frequency noise.
Hello, great video! I was wondering if you consider the time scale on the oscilloscope when you take your rms measurements. Since the rms noise on the scope is usually the integration of the signal over the sample memory period, the reading surely varies with the time division you are using, no? I understand its a rough approximation but i find this rather interesting since it can potentially influence the readings by a non negligeable amount. what do you think?
The scope must also have some BW limiting in place and the number of samples and rate must match that limit.
Having fewer samples will cause the noise to mix down and increase the displayed noise floor.
Sir any tutorial videos on designing RF transmitter receiver module circuits for remote controls eg remote control for RC car etc.
If you AC coupled the amplifier, why didn't you add a capacitor in series with the feedback resistor at (-) input to ground? You don't want to amplify the op-amp's own offset, right?
Hi great videos; question does the LM833 add any noise to the ground plane that is then converted to output noise by the amplifier?
Hello! From what I could notice the LM833 does make a bit of noise, but it's canceled out by the other op-amps high PSRR (power supply rejection ratio). From what I remember, by swapping the LM833 with another AD8676 I did not notice a major difference; in general it will be best to have all op-amps really low noise, but the only one that is truly critical is the first amplifying stage.
Loving your videos! Thanks!
i would love you to continue i am learing alot and as neteagle sid it is veryy interressting
Awesome!
Hi!
What does the 50ohm resistor do after ic2a? Is it a low pass filter for ground? With the 4.7uF cap it is only 677Hz cutoff frequency?
Awesome !👍
I like this project a lot. you don't mind me borrowing it's schematic right? :)
Of course not! I left a link to it in the description.
One condition though, if you build it, let me know how it works, I'm really curious what your results are.
In your schematic, the trimmer appears to have the two ends of the resistive element tied together and the wiper tied to ground. Is this intentional or is this an error? Often you see potentiometers connected as rheostats - i.e. a two-terminal variable resistor. One end of the resistive element is usually tied to the wiper rather than left unconnected. What is the typical resistance set point of the trimmer?
I think I needed an 100R resistor (ideally) and the only trimmer I had at my disposal was 1Kohm; The ends where interconnected intentionally to try to make it easier to adjust the value. With 1K connected the usual way the 100R point is somewhere around 10%; but with the ends interconnected, the same resistance can be obtained somewhere around 20%; If you have a 200R trimmer, than you can of course connect it the normal way
In your schematic, you have the LM833 powered by a 9V battery. The LM833 datasheet specifies a recommended operating condition of VCC,min = +/-5V. Did you use this part intentionally, knowing somehow that it will operate at voltages as low as +/-3.9V or is this a design error?
I can't say for sure what was my logic when I made the circuit; but the supply voltage seems to be manufacturer depended - OnSemiconductor and TexasInstruments LM833 require a +/-5V whereas ST has a minimum of 2.5+/- (see table 2 www.st.com/resource/en/datasheet/lm833.pdf ) I guess I was using the ST branded component so 9V was sufficient
@@FesZElectronics - Good job. I didn’t even check the ST datasheet. I just assumed all LM833’s would have the same Vcc range. Looks like I’ll be buying the ST version. Thanks for the great videos and helpful information!
Sure , but nobody mention about fact that the biggest part of noise is always coming form outside. So internal op amp noise is not an issue at all compare to enviroment. For example check your noise form guitar effects which you already built. Please prepare movie how to get rid of this. Compensation ect.
excellent
Mr Comorade !!
I'm curious, how much noise is added by your centering op-amp. Since 78xx regulators are common devices, I wonder if something can be done to reduce their noise. You used a battery for its low noise contribution. Could a linear regulator be used? The op-amp is supposed to be insensitive to supply noise. So how much would get through?
> Since 78xx regulators are common devices, I wonder if something can be done to reduce their noise.
Noise is measured over bandwidth, so reducing the bandwidth over which the output acts, reduces the measured noise. This means more filtering at the output reduces measured noise.
>You used a battery for its low noise contribution. Could a linear regulator be used?
As seen in the video linear regulators insert noise into the supply lines. This can couple directly into the measured signal (see next point). They can be used, but batteries are a convenient way to get very low noise, plus you dont need to be worried about EMI/RF coupling from outside sources.
>The op-amp is supposed to be insensitive to supply noise. So how much would get through?
If you look in the datasheet of the opamp, it usually has a quoted 'power supply rejection ratio' or PSRR. Worst case for this opamp is 106dB from +-5 to +-15V. this is the change of input offset voltage compared to PSU voltage. You can do the calculations yourself how much that would be for a noise signal of a certain bandwidth.
It is important to note, that the PSRR is usually denoted for a limited frequency band, but it is actually frequency dependent!! If you look further in the datasheet, at fig 21, you can see its frequency dependency and note that it quickly drops off at higher frequencies. Thus the type of noise signal is important to be considered too.
Fantastic -)
Hello, in your case did the metal enclosures make any difference? And did you earth ground the enclosures? In that case wouldnt there be ground loops since the scope is also earth grounded?
Hello. To be honest, I did not really notice a difference but that might be because I was working in an area that is quite EMI quiet. If there was more noise in the area than the difference might have been more noticeable.
Regarding ground, connecting each circuit element to earth ground but also in between will of course create loops as you pointed out which is not a good thing. In my case the grounding was EG to oscilloscope; oscilloscope to Amplifier; Amplifier to enclosure.
The metal enclosure is critical and must be connected to the coaxial cable shield.
Hi sir, may i ask that why you connected 2 gnd and what’s the that symbol? 2 ground symbol ?
I'm not sure what you are referring to... The symbols without a clear name are the RF connectors on the input and output - these have 4 ground pins; and I also have in top left corner a switch that also has 2 ground fixation pins.
You should use modern super low noise regulator! Not unavailable russian stuff.
Sir, can I use this command in LTSPICE for resistors? {mc(10k tc=0.0001,tol}} . As I want to do monte carlo analysis at different temperature. Is there any other alternative. Please guide me as soon as possible.
Hello Irsa. The monte-carlo command will only work on a single parameter - it doesn't care what component you are using. To use the "tc" attribute, you need to use resistors, but the mc command doesn't know this. So to use both mc and tc, the syntax would be " {mc(10k,tol)} tc=0.0001 - this way the temperature coefficient is applied on the monte carlo final value. Let me know if this works out.
Okay sure.@@FesZElectronics
@@FesZElectronics yes i cjecked it and it works.
@@FesZElectronics I have another question. Can we introduce faults in components in LTSPICE, like we can do in MULTISIM.
zone.ni.com/reference/en-XX/help/375482B-01/multisim/settingplacedcomponentsfaults/#wp245032
Please guide me. MULTISIM provides option for these kinds of faults for every places components. Is there a way to introduce faults in components in LTSPICE?
kirov reporting.
A cheap ferrite sheet, steel mesh.
What the hell! This is the biggest voltage regulator! Not just any regulator. It is RUSSIAN! One which behaves as an integrated circuit with 'null adjust'. It is an integrated circuit anyway but the small one is commonly not considered as an integrated circuit due to its common usage as a voltage regulator.
We all know how soviet engineering turned out...chernobyl yeah... dont brag about its engineering thanks
three-mile island?