11/21/2022 0 Comments 60 seconds timer![]() If the electronics will stand it, it might be possible to increase torque by running it on, say, 3 volts instead of 1.5. If it needs to be visible from all round, put the clock on its back to make the disc horizontal and let your imagination run wild. If it only needs to be seen by one student at a time, the disc could have animations or increasing bars or what-you-fancy painted on it, viewable through a window or a slit. If a light-weight disc was mounted in place of the second hand it could stop the clock once every 60 seconds by operating a microswitch with a peg or notch, or preferably by actuating an optical slot-switch with a slot or hole, on the same principle as self-parking car wipers. Though I understand your preference for a mechanical mechanism, there are high-torque quartz clock movements available quite cheaply, with a second hand. This is the sort of challenge I loved when I was working with disabled students. I'll bet that if you told the folks at the local hardware store what you're doing that they'd likely donate what you need. Less if you can score the stuff for the cam disc, box and power cord for cheap or free. Should be buildable for around $20 if you don't charge for your time. it would be quiet in use but a line of some sort would act like a rotating hand on the face of the disc. Then to start it up again just lift the clapper arm and it rides against the OD of the cam disc until it falls into the slot and dings the bell at the end of the minute. At the same time the clapper arm would stop the disc from turning. If a friction fit but slippable cam disc was attached to the arm so it could safely be stalled a slot in the disc could allow a clapper arm to drop into the slot and "ding" a bell. I just checked and 1rev/min motors are available on Amazon for under $10. Although in that case I'm thinking that the fairly noisy buzzing will be distracting. Dig into it and lighten up or otherwise modify the escapement so it "ticks" 60 times faster. make up an adapter that connects them and play with the opening at the middle and amount of sand to produce a 1 minute drop of the sand.Īnother option if you want it to go DING at the end would be to get one of the mechanical hour timers. The glass itself could be made from two small clear plastic bottles of some sort as long as they taper to a small'ish neck. ![]()
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