<html><body style="font-family: Helvetica,Arial,sans-serif; font-size: 12px;"><div>The power circuit in the RSD-10 provides 0V (ground symbol), +2V,
+4.5V, +7V and +9V. +2V/+7V (a 5V difference) are used for Vss/Vcc on
"digital" chips (e.g. IC12 - 4040 counter, IC16 - 4164 DRAM) and
0V/+4.5V/+9V are used for Vee/GND/Vdd on "analogue" chips e.g. (IC2 -
uPC1571C expander) for a bipolar supply. For example, see IC1a which is
a unity gain inverting op-amp with the + terminal at +4.5V as a virtual
ground.<br></div><div><br></div><div>Cheers,</div>A.<br><br><br><blockquote class="atmailquote"><br>----- Original Message -----<br><div id="origionalMessageFromField" style="width:100%;display:inline;background:rgb(228,228,228);"><div style="display:inline;font-weight:bold;">From:</div> "Adam Inglis" <21pointy@tpg.com.au></div><br><div id="origionalMessageToField" style="display:inline;font-weight:bold;">To:</div>"Synth DIY" <synth-diy@synth-diy.org><br><div id="origionalMessageSentField" style="display:inline;font-weight:bold;">Cc:</div><br><div style="display:inline;font-weight:bold;">Sent:</div>Mon, 10 Jun 2019 12:10:24 +1000<br><div id="origionalMessageSubjectField" style="display:inline;font-weight:bold;">Subject:</div>[sdiy] +7 and + 2 volt supply<br><br><br>
In another thread I mention a bunch of Roland/Boss delay boxes I’m looking at.<br>
Most of these take the usual Boss 9 volt supply and regulate it with a 78L05 giving a +5 to zero volt supply.<br>
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.<br><br>
Anyone care to hazard a guess as to why?<br>
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