electronic magnifying glass

Rectification is usually a question of removing the negative half-cycle (during positive rectification) or the positive half-cycle (during negative rectification) of the alternating volt- age. The reference for the resultant voltage then becomes 0 V. However, the reference level can be any other positive or negative voltage as required. This is done by removing everything above or below the reference level. An example of this is the circuit in figure 1. It is a precision rectifier which allows all of the input signal, Ui, through un- changed provided it is above the reference voltage UR (figure 2a). Negative rectification is also possible (figure 2b). All that is required is to change the polarity of diodes D1 and D2. The reference voltage can be 65 electronic magnifying glass —12... —715" preset" by potentiometer P1. The circuit works accurately enough for frequencies up to 20 kHz. What can you do with it? You can make an electronic magnifying glass. Supposing a relatively ...