- Opting for battery operated power for the sensing device (the bio-instrumentation amplifier) as well as the data acquisition inputs, for example, a laptop that runs on battery. The brightness of the laptop display maybe set to maximum, as some laptops may emit significant stray noise when brightness is not saturated.
- Switching off any fluorescent lights
- By proper Earthing of the equipment
- Using differential op-amp configuration for adequate noise suppression by eliminating common mode signals
- Using a preamplifier; and coupler gels that reduce electrical impedance (resistance) between the electrode (lead) and the body surface
- Choosing an operational amplifier having a high CMRR (common mode rejection ratio)
- By using a unity gain amplifier (voltage follower) configuration that has a very high input impedance
- Employing a noise cancelling mechanism like the 'right leg driver'
- Using a Farady Cage for effective 'shielding' from electromagnetic interference (static)
- Employing a hardware filter (band stop or Notch filter) or a software program to eliminate/reject a particular frequency band (e.g. 50 Hertz or 60 Hz cycle frequencies)
- spring constant (Hooke's Law) of the device maybe obtained by calibrating with a known device and by measuring how far the cylinder moves into the outer barrel (there's a spring inside that snaps hard onto a piezo crystal when force is applied).
Piezo based cigarette lighter producing high enough voltage causing a spark thus igniting the gas
- by coupling it to a linear potentiometer which have also been previously calibrated (see figure), and then displaying the resistance in a multimeter or through a linear dot/bar display using LM 3914 IC.
- Work done = Force*Distance=m(mass)*g(acceleration due to Gravity)*displacement (see schematic diagram)
- Desktop line-in (via Avance AC97 soundcard) input but that would entail 50 Hz hum to pass through as well.
- A stereo (tape/CD) recorder running on battery power is a better option. The data can later be played/digitized at a later time.
- A stereo FM transmitter or a 3 pin to USB adapter is yet another option.
- The internal connection pattern of (4 ring TRRS vs 3 ring stereo) 'smartphone'-'laptop' cable foxed me for some time to realize that the Left & Right channels were only capacitively coupled
- That my low-cost Penta T-Pad tablet could NOT render waveforms in BYB app while my Samsung GT-S5360 gleefully obliged. However, the screen was way too small to allow any reasonable analysis & that data longer than >=2 seconds could not be saved in the mobile
- There was significant 'clipping'/distortion of the waveform in my mobile phone [maybe I could have attached a resistor to the ground/common pin to attenuate the signal. But I opted for not modifying the device in any way.]
N.B.-Remember, electricity kills! Try to have a close friend, preferably a doc, by your side. Check that the 'Earth' outlet is really what it outta be!
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This work by Amiya Sarkar is licensed under a Creative Commons Attribution 4.0 International License.