[sdiy] +7 and + 2 volt supply

Gordonjcp gordonjcp at gjcp.net
Mon Jun 10 07:29:34 CEST 2019

On Mon, Jun 10, 2019 at 12:10:24PM +1000, Adam Inglis wrote:
> In another thread I mention a bunch of Roland/Boss delay boxes I’m looking at.
> Most of these take the usual Boss 9 volt supply and regulate it with a 78L05 giving a +5 to zero volt supply.
> However, in one of these machines, which uses much the same circuitry as the others (the RSD-10) and the same 9 volt DC adapter, Roland have used a 78L07 next to a 79L05 to give a +7 v to +2 v supply.
> Anyone care to hazard a guess as to why?

So that the digital side has a 0V/+5V supply, and the analogue side has a
-2V/0V/+5V supply which is "sufficient" given the limitations of an
unregulated 9V input?


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