More Variable Power Supplies
Variable Gain Amplifiers
AC-AC Converters VARIABLE ISOLATED AC
VOLTAGE SPANS 0VAC TO 280VAC
I designed and built this circuit about 25 years ago. It came in handy for
many projects that were powered from 120 VAC, 240 VAC and 277 VAC. It provides
complete isolation from the power line. It uses two 1:1 isolation transformers
that are wired in parallel for the140vac range and in series for the 280vac range.
The selector switch also diverts power to the appropriate output socket to avoid
mishaps in sending the wrong voltage to the load. My home-built unit also included
an AC volt and Amp meter to monitor the output. However, this circuit only
indicates the AC power connections.
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