Originally Posted by JD-EE
"If you can still get the famn dool parts."
I too am in a business where the products have longer production runs than their components, so I certainly agree about substitutions. I'd be willing to bet that the topology of the circuit has not changed much over the years.
Originally Posted by mm43
A fundamental frequency oscillator combined with a simple divider chain for other timings, and all well within specs, ...
Regarding mm43's conjecture that dividers are used, I bet not. The spec sheet (
Dukane model DK120 and DK100 Underwater acoustic locating beacons) shows a different tolerance for the frequency (1kHz/37.5kHz =2.7%) than for the pulse width and repetition rate, each at 10% (each listed as 9ms and 0.9sec from a likely, but unstated, nominal of 10ms and 1 sec, respectively). This means that they are not derived from the same time base. Dukane pingers have been around since 1969 (
Dukane Audio Visual, Ultrasonics, and Seacom Divisions), and although the first CMOS ICs appeared in 1968 (
CMOS - Development history), the pingers probably were not originally designed with digital dividers. I expect that the design is based on independent 10% tolerance one-shot timers for the pulse length and repetition rate.