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Battery Quartz Clock Control — Parallax Forums

Battery Quartz Clock Control

SparksFSparksF Posts: 1
edited 2008-04-30 23:32 in BASIC Stamp
I am a novice with the stamp and I am trying to hack a common Quartz 1.5v battery clock movement. The clock gears are driven by a magnetic rotor coil where a 6 ma current is pulsed for 50 ms at 1 volt followed by a wait state for 950 ms when the current is reversed. I want to use a Stamp BS2 to control a friend's wall clock to make him five minutes late for meetings (where the clock speed would be increased up over a subsequent interval to catch up with real time). When I started I thought this hack it would be simple. I have worked with the design of an H bridge using mosfets but it got complicated and might never drive such a small amperage load. Sometimes I feel like surrendering and just using two reversed batteries. I learned much from reading through the Parallax/Nuts + Volts articles regarding H bridge controls, but am still stumped over this simple microload circuit. Am I missing a simpler design? The ULN 2003 could be used to sink, but I cannot find a way to source and reverse current especially for this small load. Any ideas ( stamp chips are not cheap and I would rather use protection buffering logic that I could build and test separately before applying the stamp control)? Below I will try to include a first circuit drawn on ExpressSCH (needs protection diodes and coil voltage divider ) on the earlier mosfet schematic which will probably not work.
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