I have at last got around to adding a gliding tone circuit to the acoustic
radar under the fuselage (to replace the fixed threshold output the kit
normally provides). From 1.5m down it generates a tone descending from 1kHz
towards zero. Few components are needed but unfortunately I have used a
component "from the box" which I now discover comes up as "obsolete" in the
catalogues to which I have access. This may make it difficult to acquire.
So does anyone know an equivalent to the Signetics 566 chip ? It is a CMOS
voltage controlled oscillator which takes an input in the range from 12.5 v
to 7.5 volts to give the required frequency change.
Graham Clarke G-EMIN
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