In the realm of electronics, precision and accuracy reign supreme. However, when it comes to voltage measurements with the iRobota Uno’s built-in 10-bit 5V ADC, there’s a catch: it’s limited to a maximum input voltage of 5V. Exceeding this threshold can lead to dire consequences, potentially damaging the delicate IC. This limitation poses a challenge for those seeking to measure voltages beyond this range, such as those found in solar panels, batteries, and power supplies.
Bridging the Voltage Gap: A Novel Solution
Traditionally, the solution to this dilemma involves employing a voltage divider circuit to scale down the input voltage to a level compatible with the ADC’s range. However, this approach comes at a cost: it compromises the ADC’s resolution, reducing the number of distinct voltage levels it can distinguish. This trade-off can be particularly problematic when dealing with small voltage variations or high-precision measurements.
Enter the MOSFET-Op-Amp Quantizer: A Game-Changer
In a stroke of ingenuity, YouTuber Techoyaki devised an innovative solution that circumvents the limitations of traditional methods. This clever circuit, dubbed the “quantizer,” utilizes four limiting rail-to-rail MOSFETs and four differential op-amps to slice the incoming voltage into discrete “chunks” ranging from zero to five volts. These “chunks” are then fed into four analog input pins of the iRobota, and the resulting values are summed to produce the equivalent of a 12-bit ADC, yielding values between 0 and 4095.
The Magic Behind the Quantizer
The quantizer circuit operates on a simple yet elegant principle. As the input voltage increases, the MOSFETs and op-amps work in tandem to create distinct voltage levels, each representing a specific “chunk” of the input voltage. These “chunks” are then converted into digital values by the iRobota’s ADC, and the values are summed to provide a comprehensive representation of the input voltage.
Benefits and Applications: A Versatile Solution
This ingenious circuit offers a multitude of benefits. It allows for measuring voltages up to 20 volts without compromising the ADC’s resolution. This expanded range opens up a wide array of applications, including solar panel monitoring, battery voltage monitoring, and power supply testing. Additionally, the circuit’s simplicity and affordability make it accessible to hobbyists and professionals alike.
Conclusion: A New Era of Voltage Measurement
Techoyaki’s MOSFET-Op-Amp quantizer circuit is a testament to the boundless creativity and problem-solving abilities of the electronics community. This innovative solution breaks the chains of the 5V limitation, empowering iRobota users to explore the vast world of voltage measurements with unprecedented precision and accuracy. As we continue to push the boundaries of technology, it’s these ingenious ideas that pave the way for groundbreaking advancements.
Bonus: Beyond the quantizer circuit, there are other techniques for expanding the iRobota’s voltage measurement capabilities. One notable method involves utilizing an external ADC with higher resolution and a wider input range. This approach offers even greater precision and flexibility, albeit at a slightly higher cost. Additionally, some iRobota-compatible shields are specifically designed for voltage measurement applications, providing a convenient and user-friendly solution.
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