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<p>From the datasheet:<br>
"<span class="markedContent" id="page39R_mcid5"><span style="left:
118.24px; top: 226.44px; font-size: 16.6px; font-family:
sans-serif; transform: scaleX(1.02109);" role="presentation"
dir="ltr">The AS3394E was designed to operate from +5V and </span><span
style="left: 524.907px; top: 226.44px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr"> </span><span
style="left: 526.517px; top: 226.44px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr">-</span><span
style="left: 532.117px; top: 226.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.01799);"
role="presentation" dir="ltr">6.5V supplies. The non</span><span
style="left: 705.167px; top: 226.44px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr">-</span><span
style="left: 710.767px; top: 226.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.01258);"
role="presentation" dir="ltr">standard negative supply </span><span
style="left: 902.364px; top: 226.44px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr"> </span><span
style="left: 903.767px; top: 226.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.00184);"
role="presentation" dir="ltr">was </span><br
role="presentation">
<span style="left: 118.24px; top: 248.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.00406);"
role="presentation" dir="ltr">necessary not to compromise the
VCO frequency resolution, which ranges from </span><span
style="left: 710.167px; top: 248.44px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr">-</span><span
style="left: 715.767px; top: 248.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.00436);"
role="presentation" dir="ltr">4 to +4 volts, in favor of a </span><span
style="left: 907.4px; top: 248.44px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr">-</span><span
style="left: 913.2px; top: 248.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(0.996);"
role="presentation" dir="ltr">5V </span><br
role="presentation">
<span style="left: 118.24px; top: 270.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(0.999472);"
role="presentation" dir="ltr">supply </span><span
style="left: 170.812px; top: 270.44px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr"> </span><span
style="left: 174.233px; top: 270.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(0.974825);"
role="presentation" dir="ltr">(this is because there needs to
be 4 diode dr</span><span style="left: 534.717px; top:
270.44px; font-size: 16.6px; font-family: sans-serif;
transform: scaleX(0.979598);" role="presentation" dir="ltr">ops
for the current mirrors</span><span style="left: 740.367px;
top: 270.44px; font-size: 16.6px; font-family: sans-serif;
transform: scaleX(1.01349);" role="presentation" dir="ltr">).</span><span
style="left: 750.567px; top: 270.44px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr"> </span><span
style="left: 755.181px; top: 270.44px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr"> </span><span
style="left: 758.567px; top: 270.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(0.975485);"
role="presentation" dir="ltr">Any one of the readily </span><br
role="presentation">
<span style="left: 118.24px; top: 292.64px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.00248);"
role="presentation" dir="ltr">available 3</span><span
style="left: 197.833px; top: 292.64px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr">-</span><span
style="left: 203.433px; top: 292.64px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.00504);"
role="presentation" dir="ltr">terminal regulators may b</span><span
style="left: 391.883px; top: 292.64px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.00499);"
role="presentation" dir="ltr">e used to supply the </span><span
style="left: 546.117px; top: 292.64px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr">-</span><span
style="left: 551.717px; top: 292.64px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.0081);"
role="presentation" dir="ltr">6.5V negative supply. Since the
stability and jitter of </span><br role="presentation">
<span style="left: 118.24px; top: 314.64px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.01439);"
role="presentation" dir="ltr">the VCO are directly affected by
noise on the positive supply, a supply as stable and clean as
possible should </span><br role="presentation">
<span style="left: 118.24px; top: 336.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(0.999048);"
role="presentation" dir="ltr">be use </span><span
style="left: 172.633px; top: 336.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.00311);"
role="presentation" dir="ltr">(not the +5Vdigital supply</span><span
style="left: 360.483px; top: 336.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.01349);"
role="presentation" dir="ltr">) </span><span style="left:
370.683px; top: 336.44px; font-size: 16.6px; font-family:
sans-serif; transform: scaleX(1.00318);" role="presentation"
dir="ltr">Maximum supply allowable across </span><span
style="left: 628.317px; top: 336.44px; font-size: 16.6px;
font-family: sans-serif; transform: scaleX(1.00227);"
role="presentation" dir="ltr">the device is 25 volts.</span><span
style="left: 787.767px; top: 336.44px; font-size: 16.6px;
font-family: sans-serif;" role="presentation" dir="ltr"></span></span>"</p>
<p>When I've tried CEM & AS chips I've used a 78L05 for the +ve
and LM337LZ for the -6.5V (only marginally more complicated than a
79L0X type).<br>
But I've still never quite zoned in to suitable ranges &
offsets for all the control pins so my projects have always
remained stuck :(</p>
<p>Tom<br>
</p>
<div class="moz-cite-prefix">On 18/11/2021 15:31, Roman Sowa wrote:<br>
</div>
<blockquote type="cite"
cite="mid:8730e95c-d0a7-4ae6-d394-069c7d0cbe7c@go2.pl">Why not
7905?
<br>
It's -6.5V maximum, 5V recommended.
<br>
<br>
Roman
<br>
<br>
W dniu 2021-11-18 o 15:09, Benjamin Tremblay via Synth-diy pisze:
<br>
<blockquote type="cite">Greetings,
<br>
<br>
I have been intrigued by the CEM3394 for a long time. I realize
it’s the part of the Sequential Six Trak I like; the rest of the
Six Trak leaves a lot to be desired.
<br>
<br>
What is a straightforward way to obtain the -6.5V negative
supply? Use a 9V regulator and drop it with diodes? Use an
adjustable switching supply? Add a feedback loop to a regulator?
I’m assuming even a gaggle of 3394 chips won’t consume much
current on the negative side.
<br>
<br>
I’m lazy (working 2 jobs and taking care of 2 kids and a puppy)
and I won’t get much done unless I can breadboard the chip and
try out some s/h ideas.
<br>
<br>
Thanks,
<br>
Ben
<br>
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