PC Soundcard Oscilloscope buffer/attenuator. Especially for Visual Analyser.
ฝัง
- เผยแพร่เมื่อ 4 มิ.ย. 2024
- You First Order Free at PCBWay: www.pcbway.com/
I have been using the Visual Analyser Soundcard Oscilloscope software for years, and have often thought of building a buffer to reduce input noise and protect the soundcard from excessive input voltages. Until now these thoughts had remained just that - thoughts.
I recently needed to test the frequency response of a tube radio and remembered this software, which has a really great spectrum analyser function. This again stirred up those 'thoughts', so I decided to do something about it. Hence this project.
The software is free, and very complete. It is really only useful for the audio frequency ranges with a top limit of 20kHz, but for this it works really well.
This video demonstrates the build using PCBWay boards, testing, and also a short circuit description. You can get the boards on the PCBWay share page, or follow the link below to build your own. Have fun.
www.pcbway.com/project/sharep...
You can now support the channel:
/ mcaldeira
paypal.me/macaldeira
TimeStamps
00:00 SABA PC Soundcard Oscilloscope buffer/attenuator. Especially for Visual Analyser.
00:11 Introduction.
01:55 The built boards and description.
08:53 Testing the boards.
17:17 Connecting the finished project.
18:20 Testing with VA software.
26:02 Circuit description.
33:20 Closing.
#tuberadios #antiqueradio #radiorestoration
_____HUNDREDS OF OTHER VIDEOS TO CHOOSE FROM____
DIY TEST GEAR: The title says it all:
• Zener Diode Tester - P...
RESTORATION BUILDING BLOCKS: A series of videos showing detailed steps used the restoration process of tube equipment:
• How to safely check th...
HowTo's: Various videos on some simple techniques and projects:
• Extend tube radio FM b...
See also playlists on some other completed restoration projects.
PHILIPS BX750A:
• Philips BX750A tube ra...
TELEFUNKEN OPUS 2114:
• Telefunken Opus 2114 s...
SABA UW-175-Z 3D:
• Saba UW 175-Z 3D tube ...
GRUNDIG 1070:
• Grundig 1070 tube radi...
SCHAUB-LORENZ GOLDY 58 type 3020:
• Schaub-Lorenz Goldy 58...
BUSH VHF64:
• Bush VHF64 tube radio ...
GRUNDIG 3060A:
• Grundig 3060a tube rad...
TELEFUNKEN OPERETTE 8:
• Telefunken Operette 8 ...
GRAETZ SUPER 171W:
• Graetz Super 171W tube...
LOEWE-OPTA MAGNET 3737W:
• Loewe-Opta Magnet 3737...
BRAUN ATELIER 3:
• Braun Atelier 3
LOEWE-OPTA TRUXA STEREO 4741W:
• Loewe-Opta Truxa Stere...
GRAETZ COMEDIA 616:
• Graetz Comedia 616 tub...
SABA FREIBURG W2:
• Saba Freiburg W2 (WII)...
GRAETZ MUSICA 4R417:
• Graetz Musica 4R417 re...
You may also be interested in ...
CAPACITOR LEAKAGE TESTER:
• Capacitor leakage test... - วิทยาศาสตร์และเทคโนโลยี
This was a brilliant video. I really appreciate the explanation of the schematic as I actually understand how it works now!
Thanks 👍
Great work. Really like your 2 rail power supply. Thanks for the session.
pleasure
Just wow! I have been enjoying your radio repair videos for some time. Now I discover I can make my laptop into a spectrum analyser with free software, and furthermore I can get a ready made attenuator PCB. This channel is excellent. By the way, I have been to Madeira a few times. Such a beautiful island, and I love the Portuguese language, though I am not very good at it.
Next time you come over, let me know and we'll meet for a drink and a chat.
@@electronicsoldandnew Thanks for the invitation. They are normally quick visits via cruise ship to Funchal with a bit of sightseeing, eg levada walk, lava tubes, cable car, normally fortified my poncha and/or Madeira wine. I hope you have avoided the mudslides and wildfires that I witnessed the after effects of. I really appreciate your videos, they are kind of relaxing to watch and take me back to my teenage years when I used my dad's garden shed to work on electronics of the forties and fifties. I have recently resumed my old hobby, I made a solid state headphone amp. Now I am also going to design/build an OTL tube headphone amp. It will involve prototyping and testing, but initially I have spent many hours working on spreadsheet modelling so I can explore different component values, bias points, supply voltages etc. The key to this is to convert tube characteristics into data tables and use interpolation on them. Because the curves are non linear I had to use goal seek and a macro as well. I have not looked at proprietary modelling tools, it's been hugely satisfying and educational doing it in Excel. The
Well, as I write this I am looking at a huge cruise ship in the harbour 😊 My office is just on the sea front.
Enjoy the hobby, and good luck with your discoveries 😊
It really looks and works well. I mainly use the audio analyser, much like you for a spectrum analyser than a scope. I could do with some tuition on how to fly it, especially how you did that compensation adjustment.
👍
Thank you. Still trying to understand certain concepts but learning somehow..
👍
Are parts on the eagle used for strength testing without energizing?
Nice.
Just to be on the safe side.
I would add a 0.1uF non-polarized low voltage capacitor at the output of the probe.
In order to protect the output buffer IC from any DC voltage erroneously present on the output.
Like from the PC itself, failed sony plug etc.
👍
How did you design the aluminum case? Great video. Informative and fun watch. Also, for that trim pot near the output, I'm guessing you set that to voltage divide a bit depending on what signal levels you intend to probe?
The enclosure is a standard 6x6xm aluminium extruded element, with part of the top cut out.
I have a need for viewing the response ( swept response ) of a wideband amplifier circuit over a frequency range of 100 Khz to 50 Mhz. Do you have any source of circuits for high voltage use ( vacuum tube type circuit ) that would be suitable for such a project?
For that range of frequencies you’ll have to use a scope and a pretty good signal generator to produce the sweep.
I scoped it out nice work
👍
great work buddy. question, this project just work with battery or it could work with a 9v power supply?
You can use a 9V supply as long as it is completely isolated from earth. The reason is that the creation of the split rail supply will not work if the 0V of the supply is connected to mains earth, as the scope’s input ground is normally earthed.
Is your RCA output insulated or connected to the chassis? I've read your chassis should only be grounded at one point in low frequency analog circuits (preferably at the input). Otherwise you may get ground loops.
It’s best insulated
Hi, You are doing exactly what I need to do. Who's software is it? I take it that the sweep generator and scope are both part if the same software package? Is there any benefit to $250 USB "sound cards"? I have heard that most sound cards can't handle DC without modification. Is there a card that will measure DC without any modification? Great video. I will be ordering a couple of your boards for our lab. Keep up the great work!
Visual Analyser is a free software available on the web. Not sure about the advantages of more expensive sound cards.
I see you have the 1204x-e scope (I have the 1202x-e). Is the sound card method superior to using the fft function in the scope for spectrum and bode in audio. I’ve played with fft in this scope, and found it to be painstaking to get a good display, and I’m wondering how the accuracy would compare...thanks
The fft of the scope would be much more accurate, but it is a little difficult to get a meaningful display, especially at these frequency levels. These scopes have a bode plot function which is great, but my signal generator does not connect to it in a way that makes this possible, unfortunately. Need a new sub gen 😊
Unfortunately for me, Siglent only released a new firmware for the bode function for the 4 channel version. Not sure if any of the circuitry in the extra 2 channels is used or what the reason is for that. Should have gone the extra distance and got the 4 channel...thanks
👍
At 18:00 you mention the possibility of having 2 channels - how is this possible with microphone being mono? Also, is the RCA mono to microphone cable something that's easy to get, or did you have to make it yourself?
Probably dumb questions, but still.
Also, what is the minimum voltage the battery can drop to?
The two channels are left and right as the line input is stereo. Not sure what you mean about the battery as it’s been some time since I did the video.
Do you need to isolate the ground loop? Should you? I ask this as a complete beginner! Thanks
I’m afraid it’s been quite a while since I built this. I use it often, but don’t recall the details.
Great video as usual, Manuel. Can you explain to a dummy like me what is the purpose of that opamp in the power supply?
It takes the 4.5V from the resistor divider and stabilises it to allow it to supply/sink some current without altering the set voltage. It creates a pseudo-ground from a single battery supply.
@@electronicsoldandnew OK, thanks.
Kari Sillanmäki I get it somewhat but I’d love graphics.
When I got back into Electronics I tried doing the Sound Card Scope thing with VA and kept having issues. Kinda wish the software was cross platform for Linux as well.
I’ve used it for years, on and off. Sometimes it was frustrating, but I never gave it up because of the spectrum analyser function.
Thank you so much, I have been using ARTA software with an Attenuator between sound card and DUT. I like this much better, I ordered the card from PCBway, but it would be much easier for me if you could provide a parts list. I know I can refer back and forth to the video for the schematic, but a parts list or a hard copy of the schematic would really help. The parts list would also let me start ordering parts while I wait for PCB.
I actually don’t have a parts list, as I normally just “speak through” all the details. I’m sorry
@@electronicsoldandnew No problem I am grateful for what you have shared. I was able to freeze the video at the point where you had all three sections of the schematic on the display and it looks like you have all the parts listed. Am I correct to assume that the 3 parts of the schematic cover all the parts? PCBway just confirmed they shipped the PCBs and I can't wait to build and test it. Thanks again.
Yes, it’s all there. Have fun building it.
These days some soundcards go well over 192kHz samplerate. Some even up to 384kHz and 768kHz. Quite useful actually, up to half the samplerate. SNR well up to 110dB isn't rare these days either.
Btw, I would recommend looking into ARTA. A program a little bit more focused on loudspeaker measurements, but it also works very well for Bode plots, measuring THD etc. I use it a lot for measuring amplifiers.
I e seem ARTA and will probably be experimenting with it, but I really must replace this old sound card 😊
@@electronicsoldandnew I use an Asus Xonar DX, which has actually superb specs for its price. Can be found 2nd hand for cheap. (or de Xonar D1 for old PCI version)
Otherwise, just get a decent USB audio interface :)
But sound card has its own limit as it has low pass filter to sound bands it allows passing in.
hello master, does this device show the xy curve of the components in the computer?
Only if the software you’re using provides that function.
There is an xy chart section in the application, but can it be used?
Is it possible to measure materials such as diodes, capacitors, zener diodes?
first of all thank you for the nice video ! it was been really usefull.
I was fighting against the non flatness of the measure when I was using its sweep generator !!!
unfortunately i didn't solved ... I discovered that my soundcard has really a bad audio generator response... The generator output is not flat at all and starting around 15Khz it start to degrade about reaching 23 dB less when it stops at 20Khz. no way to compensate that even using the good tips you showed. may be it is my soundcard limit.... i will try with another audio card (this other one is usb card and much more good than the onboard one) .
👍
31:00 Not only will it reduce the 10 volt signal down by 4.5 and a diode drop, (thats correct for DC voltage) but for a higher Frequency, say 1 Khz the +4.5 and -4.5 will be a dead short to ground. Remember those 100uF caps. So the signal om to the opamp wouldn't be much more than the 0.7 volt diode drop. I think....
You are absolutely correct. One gets so used to putting this diodes as input protection that you don’t even think about what exactly it is they are doing. However, here it is fine because more than 1.4VPP is probably not a good idea for the sound card anyway.
I think it is independent of frequency. The diodes will only conduct when you exceed approx plus or minus 5.1 volts no matter how quickly or slowly you approach those limits. If both diodes went to ground instead of supply rails you would limit the swing to plus/minus the diode volt drop.
That frequency generator can be a bit confusing. 20 Hz shows 20.000.000 Hz on screen. Makes you think its 20 MHz. I do get it that it allows you to set very accurate frequencies. Still, I find it missleading. Thanks for the video.
pleasure
A simple PC sound card scope is just full of noise at high gain .
Need 2 inputs your out of luck !
But you can clean up 1 channel by about 50 % .
Null the noise invert the unused channel 2 & add it with channel 1 .
Set ch 1 gain as ch 2 .
Yes, the inputs can be noisy. Just how noisy depends on the sound card you have. However, this system is good enough for my specific needs. If you want more exact measurements, a real scope is essential. I have two, but still prefer this system for frequency response plots.
Thanks.
Have to look, if there is a software for linux available. (No, i don't install wine)
Thanks for the inspiration.
good luck with the search
Re the high frequency roll off. I'm not currently convinced it's your sound card. I'm getting exactly the same result using an external USB audio interface. I'm in the cave right now doing some tests to find the offending device.
👍
@@electronicsoldandnew Found it. It's on the output side, it's simply the low pass filtering to prevent aliasing. If you increase the sample rate, the roll off frequency increases.
👍 thanks
Try eigher 384000 samples per second or 768000 samples per second.
th-cam.com/video/yf_u7vza-Is/w-d-xo.html it possible to measure like this device?
And here my sound card probe is like 2 diodes, a cap, and pot (dead bug wired inside a small box)... I now have probe envy (envy is an ugly thing) lol
i’d it works, it’s good 😊
This is sound card circuit all software support its is ya no