Or even better use a scope, then you can see what you are measuring.
The OP probably does not understand that the output load needs to be 50 ohm. If you not load the generator with 50 ohm the output voltage is usually double the output voltage you set on the generator.
Or for the el cheapo chinese the unloaded output is the set voltage and as soon as you put a load on the output the voltage drops.
Benno
The E1DA ADC has input impedance of 640 Ohm while the Scaler has input impedance of 200k Ohm. What would happen to the signal generator with 50 ohm output impedance in them?
No. I just wrote 1.00001V to drive the point that it should not be 1.2V or 0.9V but exactly 1V. It doesn't have to be 1.00001V but only 1.01 volt for example. It is enough.
My multimeter has this specs up to 500Hz only. What best inexpensive multimeter that can measure at least 10Hz to 20000Hz with accuracy of 1/100000th (ops, i mean just accurate enough in 2.01V or 3000.01 Hz?
Hello,
blue has small disturbances in the image 5khz.png.
Best regards
egonotto
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?
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?
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
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?
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?Simple: get a step attenuator and connect it to the output of a signal generator.
If your budget is low, why don't you try in the first place what I suggested here:
https://www.eevblog.com/forum/testgear/most-accurate-signal-generator/msg5413988/#msg5413988
That cost's you a few cents for two 1% resistors.
You are asking for a SINAD of ~35dB. That's not really challenging for a signal generator.
I guess that even your FNIRSI toy can reach that, at least at the full scale level of the DAC
(EDIT: and 10µV are then obtained by dividing (say) 1V by 100,000 with a voltage divider, which does not increase SINAD).
The noise floor of your DUT (see your other threads) is significantly higher anyway.
EDIT:
And if I look at the spectrum plots in your other thread, then I cannot see that your ECG simulator did increase the random noise floor significantly. But yes, its signal obviously contains several undesired spurs. Additionally, your setup seems to pick up mains hum (and possibly some other noises) from the environment. I don't know, but I rather don't think this is coming out from your ECG simulator. So also take measures to minimize any pick-up of undesired signals from the environment.
I'd start with measuring with the inputs of your ADC shorted and go from there.
Filters do not have infinitely steep slopes. Likely the bandwidth filters on your equipment are first or second order at most in order not to create too much phase shifts. The source of the 1kHz signal can be anything (for example an intermodulation product from a noise source, including poor grounding). I'd start with measuring with the inputs of your ADC shorted and go from there.
Filters do not have infinitely steep slopes. Likely the bandwidth filters on your equipment are first or second order at most in order not to create too much phase shifts. The source of the 1kHz signal can be anything (for example an intermodulation product from a noise source, including poor grounding). I'd start with measuring with the inputs of your ADC shorted and go from there.
I mean I want to get a signal generator so I can output 10uV and 1kHz to see what the waveforms and noises look like at 1kHz because all I experienced seeing are always 50Hz signal. I havent see what 1kHz signal with noise looks like.
Filters do not have infinitely steep slopes. Likely the bandwidth filters on your equipment are first or second order at most in order not to create too much phase shifts. The source of the 1kHz signal can be anything (for example an intermodulation product from a noise source, including poor grounding). I'd start with measuring with the inputs of your ADC shorted and go from there.
I mean I want to get a signal generator so I can output 10uV and 1kHz to see what the waveforms and noises look like at 1kHz because all I experienced seeing are always 50Hz signal. I havent see what 1kHz signal with noise looks like.
The method I suggested with your FNIRSI generator can also be done at 1 kHz. Only the amplitude calibration (if you don't trust the generator) with the DVM needs to be done at a frequency which is within the spec of your DVM -- thereafter you can also tune the generator to a higher frequency. I would not expect the generator to show a significant amplitude deviation between 50 Hz and 1000 Hz.
To get a first impression what to expect, I would just capture the noise floor with shorted input and add an artificial 1kHz tone (with 3dB lower amplitude to account for the filter) in Audacity.
Aha, just do as I wrote before: get an RF step attenuator (like this one from Aliexpress: https://nl.aliexpress.com/item/32905603744.html ) and connect it between the generator output and the ADC. You'll need to terminate the step attenuator with 50 Ohm so you'll need a 50 Ohm feedthrough terminator.
Aha, just do as I wrote before: get an RF step attenuator (like this one from Aliexpress: https://nl.aliexpress.com/item/32905603744.html ) and connect it between the generator output and the ADC. You'll need to terminate the step attenuator with 50 Ohm so you'll need a 50 Ohm feedthrough terminator.
Are the inside of the RF step attenuator composed of resistor dividers? I actually did the following before:
(Attachment Link)
I connected 1Mohm in series with 1k ohm. Then when I want to lower the voltage by 0.001. I connect the input to the 1k ohm resistor, so that 1V become 1mV, and 1mV become 1uV. isn't this accurate? I don't use it with my cheap F-Nirst and FG-100 signal generators because I can't tell 1V from 2V and my multimeter is 20 year old and only up to 500Hz. Ok. I'll look and buy the best suggestions made here. Since it would take time for them to arrive. For those with signal generator, RF step attenuator and amplifier. Pls try the following:
Set your amplifier to bandwidth between 1kHz to 5kHz.
Set your signal generator to 10uV, 50Hz using RF attenuator or resistor divider. Take the screenshot of the noise at 10uV, 50Hz. Now set your signal generator to 10uV, 1000Hz. I want the see noise difference between 50Hz and 1000Hz in the signal generator with the amplifier set to 1kHz in all settings. Please show the waveforms. I want to see the noise deviation or appearance between 50Hz and 1000Hz. I want to know what to happen to the huge noise seen at 50Hz when signal generator is set to 1000Hz. whether you can still see the noise and to what degree. This is what I couldn't see all these months. Thanks.
Are the inside of the RF step attenuator composed of resistor dividers? I actually did the following before: