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| egonotto:
Hello, blue has small disturbances in the image 5khz.png. Best regards egonotto |
| Anthocyanina:
--- Quote from: egonotto on March 27, 2024, 03:25:07 am ---Hello, blue has small disturbances in the image 5khz.png. Best regards egonotto --- End quote --- yeah, that's a 50khz switching noise signal riding on it. i connected the keysight using long alligator clips as that's what i had laying around the closest to me, for later captures i just disabled the "acquire noise" option on the AD2 |
| loop123:
Guys. Besides needing 1.8V, 3000Hz to calibrate the E1DA ADC. I also need a 10uV signal generator at least 1000Hz with differential output to test my 16 channel USBamp bioamplifier directly in differential inputs. as well as the BMA bioamplifier. I got the following at Audacity. I can't figure out if its due to the Netech EEG simulator output that has noise or those amplifiers. Do you know any 10uV signal generator at 1000Hz (what is the highest possible without noise) that won't produce any noise or at least imperceptible? |
| ebastler:
--- Quote from: loop123 on March 29, 2024, 02:11:43 pm ---Do you know any 10uV signal generator at 1000Hz (what is the highest possible without noise) that won't produce any noise or at least imperceptible? --- End quote --- Before you start buying more equipment, you should read up on fundamental noise contributions and limitations. For starters, there is resistor noise (Johnson noise) which you can't avoid, even with the most expensive source and detector -- unless you go to cryogenic cooling. The web page below explains some fundamentals and has a handy calculator. You will find that at room temperature, for 10 kHz bandwidth and 1 MOhm input resistance (as found on oscilloscopes), the Johnson noise is already 13 µVrms. https://www.omnicalculator.com/physics/resistor-noise |
| loop123:
--- Quote from: ebastler on March 29, 2024, 02:36:32 pm --- --- Quote from: loop123 on March 29, 2024, 02:11:43 pm ---Do you know any 10uV signal generator at 1000Hz (what is the highest possible without noise) that won't produce any noise or at least imperceptible? --- End quote --- Before you start buying more equipment, you should read up on fundamental noise contributions and limitations. For starters, there is resistor noise (Johnson noise) which you can't avoid, even with the most expensive source and detector -- unless you go to cryogenic cooling. The web page below explains some fundamentals and has a handy calculator. You will find that at room temperature, for 10 kHz bandwidth and 1 MOhm input resistance (as found on oscilloscopes), the Johnson noise is already 13 µVrms. https://www.omnicalculator.com/physics/resistor-noise --- End quote --- I know all the noises in my BMA amplifier. The following is the computation of the approx total noise. I need to get a high quality 10uV 1000Hz signal source because I'm going to build a 1nV/Sqrt (Hz) noise INA849. So please give the 10uV signal generator of purest quality with the highest bandwidth possible. main noise sources in the signal path of the BMA are: Source resistance (e.g. 10 kOhm) 2x 5k protection resistors 2x op amps (8 nV/sqrt Hz for the the OPA2132P) Instrumentation amp (5 nV/sqrt Hz for the AMP01). For bandwidth of 1 kHz: So the calculation becomes: 10k Source resistance: 0.13 * Sqrt (10000) * Sqrt (BW) = 411 nV rms 2x 5k Protection resistors: Sqrt(2) * 0.13 * Sqrt (5000) * Sqrt (BW) = 411 nV rms 2x OP amps: Sqrt(2) * 8 * Sqrt (BW) = 357 nV rms I amp: 5 * Sqrt (BW) = 158 nV rms The noise powers sum: Total = Sqrt (411 ^2 + 411 ^2 + 357 ^2 + 158 ^2) = = Sqrt (168,921 + 168,921 + 127449 + 24,964) = Sqrt (659,176) = 812 nV rms = 0.812uV rms x 6.6 = 5.3592uV peak to peak Without source impedance of 10k Ohm. Total noise = 566.83nV = 0.566uV rms x 6.6 = 3.7356uV peak to peak Bad for 10uV. So will go for the ultimate 1nV/Sqrt (Hz) INA849. Does anyone know of any complete equipment that uses the INA849? |
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