Dear Sir-I hesitate to imply any sort of criticism of your excellent organ, but I must comment on the recent article "AVR, dB and LDR Collide" by Daniel Rodrigues. Daniel is very critical of a design using a light dependent resistor (LDR) in a digitally controlled volume control. The basis of his criticism is the resistive range of an LDR was only 50 to 2000 ohm. In fact there are plenty of LDRs available with dark resistance of up to 25 megohm which is altogether a different kettle offish. In this sort of application an LDR could be used very effectively as one leg of a potential divider, to replace a conventional potentiomer in a low-level part of the circuit. In some configurations this device can be made to approximate a log-law potentiometer for audio applications. This not only provides a solid-state alternative to a potentiometer, but also makes it easy to create multi-ganged devices controlled by a single voltage source.
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