Hi everyone,
I am trying to design a EMG circuit as a sensor for a robotics project I'm working on. I have came up with a design based on design's I've found on the internet and my limited knowledge of op-amps and analog circuitry. (see attachment, sorry if its blurry - i dont have a scanner and my iphone camera sucks)
I can get the diff. amplifier portion of the circuit working (MAX666CPA, LMC6041IN, INA106) by itself but when i try to connect the rectifier circuit (low pass filter, high pass filter, and TL084) not only does it not work but, even after I disconnect the rectifier circuit, the diff. amplifier portion stops working and only will output a constant ~ -1.17V. I checked to make sure the power supply circuit is still functioning and is in fact generating 5V with a 2.5V virtual ground. Usually if I just turn it off and let it sit overnight, it will start working again in the morning but that sometimes doesn't even work.
What the heck is going on? I'm at wits end trying to debug it. I've tried creating a separate 5V power supply circuit with 2.5V virtual ground to power the second portion of the circuit and also have tried using a dual supply (+/-9V) to power the second portion.
When the diff. amp portion of the circuit is working, it produces a signal around the magnitude of 20mV. The point of the rectifier circuit is to filter, rectify, envelope and amplify the signal to around 4V (or at least to a scale thats within the 5V detection range of my MCU).
Does anyone know why this intermittent functionality is happening?
here's the data sheets on the chips in the design:
http://focus.ti.com/lit/ds/symlink/ina106.pdf
http://datasheets.maxim-ic.com/en/ds/MAX663-MAX666.pdf
http://www.national.com/ds/LM/LMC6041.pdf
http://focus.ti.com/lit/ds/symlink/tl081a.pdf
Thank you for your time!
I am trying to design a EMG circuit as a sensor for a robotics project I'm working on. I have came up with a design based on design's I've found on the internet and my limited knowledge of op-amps and analog circuitry. (see attachment, sorry if its blurry - i dont have a scanner and my iphone camera sucks)
I can get the diff. amplifier portion of the circuit working (MAX666CPA, LMC6041IN, INA106) by itself but when i try to connect the rectifier circuit (low pass filter, high pass filter, and TL084) not only does it not work but, even after I disconnect the rectifier circuit, the diff. amplifier portion stops working and only will output a constant ~ -1.17V. I checked to make sure the power supply circuit is still functioning and is in fact generating 5V with a 2.5V virtual ground. Usually if I just turn it off and let it sit overnight, it will start working again in the morning but that sometimes doesn't even work.
What the heck is going on? I'm at wits end trying to debug it. I've tried creating a separate 5V power supply circuit with 2.5V virtual ground to power the second portion of the circuit and also have tried using a dual supply (+/-9V) to power the second portion.
When the diff. amp portion of the circuit is working, it produces a signal around the magnitude of 20mV. The point of the rectifier circuit is to filter, rectify, envelope and amplify the signal to around 4V (or at least to a scale thats within the 5V detection range of my MCU).
Does anyone know why this intermittent functionality is happening?
here's the data sheets on the chips in the design:
http://focus.ti.com/lit/ds/symlink/ina106.pdf
http://datasheets.maxim-ic.com/en/ds/MAX663-MAX666.pdf
http://www.national.com/ds/LM/LMC6041.pdf
http://focus.ti.com/lit/ds/symlink/tl081a.pdf
Thank you for your time!
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