Thread: Yaesu FT290
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Old 18th Jul 2021, 5:10 pm   #2
G6Tanuki's Avatar
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 11,361
Default Re: Yaesu FT290

Not sure about your particular circuit but in times-past I built a 1750Hz repeater-toneburst into a Pye "shaver"-style mic casing, using a CMOS chip for the crystal-osc/divider and powering it from a tiny wire-ended NiCd battery of the type intended for memory-backup.

Cunning trick: the battery was charged through a 1N4148-and-5K-resistor combination across the PTT switch; when the PTT was open there was 12V across it and 'stealing' a couple of milliamps to charge the battery was insufficient to cause any issues.

These days I'd use a 'supercapacitor' rather than a battery - either way it should be able to provide a few mA for your processor - just so long as your transmit:receive duty-cycle is sensible and gives the charge-storage-device enough time to refresh itself between 'overs'.
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