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| en:elektronik:wechsellichtschranke [2023-05-27 12:11] – created rainer | en:elektronik:wechsellichtschranke [2024-09-29 07:35] (current) – R1 optional; typo rainer | ||
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| ====== Proximity Sensor with PLL-IC ====== | ====== Proximity Sensor with PLL-IC ====== | ||
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| + | R2 determines the sensitivity; | ||
| + | if too large, strong stray light may overdrive the sensor. | ||
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| + | R3 and C4 determine the frequency and need only be changed if stray light of the same frequency is very strong. | ||
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| + | Q1 is the LED driver and delivers the signal in the right phase; R4 determines the current through the LED. | ||
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| + | The output at pin 8 is an open collector transistor switched on if the PLL locks, i.e. reflecting surface or not disrupted. | ||
| + | It can drive 100mA (on) and withstand 15V (off); the resistor R1 is shown only for convenience. | ||
