The clock portion is digital but the bell is analog and sounds like Grampa’s old wind up alarm clock. This drives a slightly beefy transistor which in turn drives an electromagnet to hammer a bell which broke off my bicycle. The switches’ outputs gets ANDed with a 10 Hz signal (on a 60 Hz grid it will become 12 Hz). As for triggering from the decade counters, here’s what told us about the design: The use of a hard disk read head turns out to be the perfect striker, as heard in the video after the break. The clock is driven by the 50 Hz line voltage and tried using that AC to drive a solenoid as the striker on the prototype unit but it performed poorly. ![]() Thumb screw wheel switches at the top of the bulky handheld unit are how the alarm time is set, triggering a bell along the top edge. It’s not, as each row corresponds to a pin on the CD4017 decade counters that make up the timekeeping circuit inside. created an industrial voltage alarm clock out of decade counters that looks like it was unearthed from a fallout shelter ( machine translation).Īt first glace you might mistake this for a binary clock since it uses a column of LEDs to indicate each digit of 24-hour time. ![]() All the hardcore geeks have alarm clocks where the bell striker is a hard disk read head… or at least they’ll be building them after seeing this.
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