<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Thanks All!<div class=""><br class=""></div><div class="">I can’t get advice like this anywhere else. Only other lazy impulse left in me is: I might actually have some 7906 regulators in a bin. Maybe good enough?<br class=""><div class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Nov 19, 2021, at 5:59 AM, The SynthiMuse via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" class="">synth-diy@synth-diy.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="auto" class="">I think adjusting the voltage on a 7905 with diodes in a non-critical supply is fine except it reminds me.... <div dir="auto" class=""><br class=""><div dir="auto" class="">As a 23 year old junior tech (1981), I got a gentle 'bollocking' for replacing a VCS3 -ve power regulator with a 7905 and a zener to bring it up to the right voltage.</div><div dir="auto" class="">He told me that so much of the synth depended on good PSU regulation that doing this wouldn't give a solid enough rail for stable operation as the voltage could drift up and down with temperature.</div><div dir="auto" class="">I learned my psu lesson.</div><div dir="auto" class=""><br class=""></div><div dir="auto" class="">So, overall, an LM337-type solution is the one I would go for.</div><div dir="auto" class=""><br class=""></div><div dir="auto" class="">Gerry</div><div dir="auto" class=""><br class=""></div></div></div><br class=""><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, 19 Nov 2021, 09:34 Gordonjcp, <<a href="mailto:gordonjcp@gjcp.net" class="">gordonjcp@gjcp.net</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Thu, Nov 18, 2021 at 03:49:00PM +0000, Tom Bugs via Synth-diy wrote:<br class="">
> necessary not to compromise the VCO frequency resolution, which ranges from<br class="">
> -4 to +4 volts, in favor of a -5V<br class="">
> supply (this is because there needs to be 4 diode drops for the current<br class="">
> mirrors).Any one of the readily<br class="">
> available 3-terminal regulators may be used to supply the -6.5V negative<br class="">
<br class="">
So why not a cheap readily-available 7905 with two diodes in its ground leg?<br class="">
<br class="">
-- <br class="">
Gordonjcp<br class="">
<br class="">
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