On 8/22/2017 4:30 PM, Adrian Graham via cctalk wrote:
Hi folks,
Failing Atari PSU aside I remembered a question I had ages ago but never posted
about the power circuit of another 80s home micro, the Enterprise 64. This
machine is powered by a 2A 9V unregulated PSU and internally there’s a pair of
7805s and a 78L12 to smooth things out.
There’s also a small transformer coil in there too (L1 on the following
schematic) and I’m not entirely sure what it’s for. Here’s the schematic of the
original circuit, any enlightenment gratefully received since I have an
Enterprise 64 with a dead coil :)
http://www.binarydinosaurs.co.uk/ep64PowerRegulators.png
<http://www.binarydinosaurs.co.uk/ep64PowerRegulators.png>
Cheers!
—
Adrian/Witchy
Binary Dinosaurs - Celebrating Computing History from 1972 onwards
It is part of a switching power supply to boost the 9VDC input to 13.7V or
greater so that the 78L12 can regulate it down to 12V.
L1 is dual purpose; it provides feedback to the boost switching regulator
oscillator (the tap) and is the main inductor for the boost supply generator.
