<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
p.MsoPlainText, li.MsoPlainText, div.MsoPlainText
{mso-style-priority:99;
mso-style-link:"Texte brut Car";
margin:0cm;
font-size:11.0pt;
font-family:"Calibri",sans-serif;
mso-ligatures:standardcontextual;
mso-fareast-language:EN-US;}
pre
{mso-style-priority:99;
mso-style-link:"Préformaté HTML Car";
margin:0cm;
font-size:10.0pt;
font-family:"Courier New";}
span.TextebrutCar
{mso-style-name:"Texte brut Car";
mso-style-priority:99;
mso-style-link:"Texte brut";
font-family:"Calibri",sans-serif;
mso-ligatures:standardcontextual;
mso-fareast-language:EN-US;}
span.PrformatHTMLCar
{mso-style-name:"Préformaté HTML Car";
mso-style-priority:99;
mso-style-link:"Préformaté HTML";
font-family:"Consolas",serif;}
span.EmailStyle24
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;
mso-ligatures:none;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:70.85pt 70.85pt 70.85pt 70.85pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=FR-CA link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p>>> I.e. Vout from the boost converter, via resistor 1k to the transistor base, zener from base to gnd to delimit the voltage.<br>But doing so I’ll need a 15vdc zener (and also a 30vdc zener for the other BUCK) and I’ll have to readjust the BUCK<br>Vout to eliminate the base/emitter .6v drop.. <o:p></o:p></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=FR>De :</span></b><span lang=FR> Synth-diy <synth-diy-bounces@synth-diy.org> <b>De la part de</b> René Schmitz<br><b>Envoyé :</b> 16 février 2024 12:26<br><b>À :</b> synth-diy@synth-diy.org<br><b>Objet :</b> Re: [sdiy] BUCK stepup converter module... output goes way too high on startup !!!<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p>Maybe use an NPN emitter follower as a pass element instead of the resistor. Doesn't load the converter, and you don't need heavy duty zeners either. <o:p></o:p></p><p>I.e. Vout from the boost converter, via resistor 1k to the transistor base, zener from base to gnd to delimit the voltage.<o:p></o:p></p><p><o:p> </o:p></p><p>Best,<o:p></o:p></p><p> René<o:p></o:p></p><p><o:p> </o:p></p><div><p class=MsoNormal>Am 16.02.2024 um 17:45 schrieb Jean-Pierre Desrochers:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoPlainText>Hi all,<o:p></o:p></p><p class=MsoPlainText> <o:p></o:p></p><p class=MsoPlainText>I’m using this type of stepup voltage regulator to generate +15vdc and +30vdc<o:p></o:p></p><p class=MsoPlainText>From an incoming single +9vdc power adapter.<o:p></o:p></p><p class=MsoPlainText>These BUCK’S converters generate very good regulated voltage outputs but I noticed<o:p></o:p></p><p class=MsoPlainText>that on power up they ‘need’ to rise up to around +48vdc<o:p></o:p></p><p class=MsoPlainText>Before settling down to their trimmed voltages.<o:p></o:p></p><p class=MsoPlainText>Well these 2 voltages will supply a DSP module @ +15vdc (not more !!!)<br>and a dual opamp TL072 that has a maximum allowed supply voltage of +/- 18vdc (36vdc overall).<o:p></o:p></p><p class=MsoPlainText>I tried putting a 16v zener diode in parallel with the trimmed +15vdc<o:p></o:p></p><p class=MsoPlainText>But the BUCK goes wild (input current rise up to around 2.5 amp and stays there !!)<o:p></o:p></p><p class=MsoPlainText>I also tried to put an RC circuit at the input (33ohms + 100uf) of one of these BUCKs<o:p></o:p></p><p class=MsoPlainText>But again the modules rise its input current to ‘try’ stabilize the regulation..<o:p></o:p></p><p class=MsoPlainText>Even with 100ohms resistors and 16v zeners.. the BUCKs won’t start<br>and finalise their outputs (inrush current installs).<o:p></o:p></p><p class=MsoPlainText> <o:p></o:p></p><p class=MsoPlainText>So.. I’m stuck with this problem..<o:p></o:p></p><p class=MsoPlainText>Any possible solutions ???<o:p></o:p></p><p class=MsoPlainText><span style='mso-ligatures:none'><img width=1302 height=1286 style='width:13.5625in;height:13.3958in' id="Image_x0020_5" src="cid:image001.jpg@01DA60D4.EC18C330"></span><o:p></o:p></p><p class=MsoNormal><br><br><o:p></o:p></p><pre>________________________________________________________<o:p></o:p></pre><pre>This is the Synth-diy mailing list<o:p></o:p></pre><pre>Submit email to: <a href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a><o:p></o:p></pre><pre>View archive at: <a href="https://synth-diy.org/pipermail/synth-diy/">https://synth-diy.org/pipermail/synth-diy/</a><o:p></o:p></pre><pre>Check your settings at: <a href="https://synth-diy.org/mailman/listinfo/synth-diy">https://synth-diy.org/mailman/listinfo/synth-diy</a><o:p></o:p></pre><pre>Selling or trading? Use <a href="mailto:marketplace@synth-diy.org">marketplace@synth-diy.org</a><o:p></o:p></pre></blockquote><pre>-- <o:p></o:p></pre><pre>--<o:p></o:p></pre><pre><a href="mailto:synth@schmitzbits.de">synth@schmitzbits.de</a><o:p></o:p></pre><pre><a href="http://schmitzbits.de">http://schmitzbits.de</a><o:p></o:p></pre></div></div></body></html>