Isolating Analog Voltage for PIC Microcontroller Using Opto-Isolator: Safe Method?

The discussion addresses the safety and feasibility of measuring analog voltage with a PIC microcontroller using an opto-isolator for isolation. The circuit in question is a difference amplifier with gain, typically involving an LM258 op-amp, and the user is concerned about protecting the microcontroller from high voltage damage. It is noted that a simple opto-isolator does not provide a linear analog output over a wide dynamic range, and specialized high-linearity optocouplers or alternative isolation methods may be required. The importance of proper PCB layout, resistor voltage ratings, and safety considerations is emphasized, especially when measuring high voltages (potentially hundreds of volts). Alternatives such as using transformers for AC voltage stepping down or Hall effect sensors for current measurement are suggested. Additionally, isolated DC-DC power supplies with push-pull circuits can be used to achieve galvanic isolation for different loads. Overall, while the circuit may be safe under normal conditions without hazardous voltages or ground loops, careful design and component selection are critical to ensure microcontroller protection and measurement accuracy.
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