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Day archives: January 17th, 2022

Circuits – Offset tuning indicator for CW

MORSE KEY

An NE567 tone decoder, tuned to the transceiver`s CW offset frequency, ensures that the transceiver will be transmitting on the same frequency as the received CW signal. Simply tune the transceiver so that the LED lights. Eight to 13 Vdc is required; this can be taken from the transceiver supply or an extra battery. Audio …

Circuits – Simple tester checks LCDs

LCD CHECKER

Manufacturers of electronic equipment use LCDs for calculators, watches, mini-videogames, and pagers, for example. In comparison with LED-based displays,which consume power on the order of tens of milliwatts, an LCD consumes onlya few microwatts. The LCD thus saves power by a factor of approximately 1000. Checking an LED is as simple as checking a semiconductor …