This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.
This list includes a generic resistor set
as a placeholder — it is not matched to the exact value or part number this circuit needs. The correct one is specified on the original source page linked above; check it before buying.
The Human-Machine Interface through Electromyography project captures electrical signals generated by muscle contractions using surface electrodes attached to the skin. Because raw muscle signals are extremely weak and masked by background noise, the system relies on a specialized analog front end to condition the signal. First, the signals pass through connectors and into an INA122 instrumentation amplifier (IC1). This component is chosen for its high common-mode rejection ratio, allowing it to amplify the tiny differential voltage between the electrodes while ignoring electrical noise that is common to both inputs. Resistors (R1) and capacitors (C1) are configured around the amplifiers to set precise gain and filtering characteristics, stabilizing the circuit and limiting unwanted high-frequency interference. Following the instrumentation stage, an OPA2241 operational amplifier (IC2) provides further signal conditioning, buffering, and amplification. The conditioned analog output is then routed through an audio jack to a battery-powered supply setup, ensuring isolation from mains electricity. Finally, users can visualize and analyze the recorded muscular activity in real time by connecting the output to PC-based oscilloscope software, such as Zeitnitz Scope.
Why Build This
Gain hands-on undergraduate engineering experience designing low-noise biomedical analog front ends for bio-potential acquisition.
Develop functional human-machine interfaces capable of translating biological muscle activity into measurable control signals for robotics and prosthetics.
Learn to process and visualize weak physiological signals using operational amplifiers, instrumentation amplifiers, and PC oscilloscope software.
Care must be taken to isolate the patient from ground. The patient must not touch any grounded metal, which can cause drainage of common-mode voltage and raise the amplitude of the output, injecting noise.
Technology Tags
ELECTROMYOGRAPHY
EMG
ANALOG FRONT END
INSTRUMENTATION AMPLIFIER
OPA2241
INA122
SIGNAL ACQUISITION
BIOMEDICAL ELECTRONICS
Frequently Asked Questions
A battery power supply helps isolate the circuit and the user from mains power, significantly reducing 50/60Hz electrical interference and improving safety during biomedical measurements.
The INA122 amplifies the tiny voltage differences picked up by the electrodes on the skin while actively rejecting common-mode noise that affects both input leads equally.
No, the project is designed to output signals through an audio jack so you can use PC-based oscilloscope software like Zeitnitz Scope for visualization.
Gallery
This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.
10pcs - 220 ohm 1/4 W Resistor Set
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