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</o:shapelayout></xml><![endif]--></head><body lang=FR-CA link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='mso-fareast-language:EN-US'>Tests made on the +15vdc BUCK output :<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>100 ohms resistor to the GND.. no startup.. inrush current.<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>Even with a 1k ohms resistor to the GND the BUCK won’t settle up.<o:p></o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:EN-US'>When the BUCK starts to work correctly it’s when the >30vdc output riseup starts to occurs..<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> The SynthiMuse <<a href="mailto:synthimuse@gmail.com">synthimuse@gmail.com</a>> <br><b>Envoyé :</b> 16 février 2024 12:05<br><b>À :</b> Jean-Pierre Desrochers <<a href="mailto:jpdesroc@oricom.ca">jpdesroc@oricom.ca</a>><br><b>Cc :</b> Synth DIY <<a href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>><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><div><p class=MsoNormal>Hi Jean-Pierre <o:p></o:p></p><div><p class=MsoNormal>It might be a load issue. Most buck regulators need a minimum load of about 5% to 10% of their max rating. <o:p></o:p></p></div><div><p class=MsoNormal>It could be that you're not loading it appropriately and it's struggling to establish on startup.<o:p></o:p></p></div><div><p class=MsoNormal>Not a solution, but if you give it an appropriate resistive load, it might give you an insight in to the problem.<o:p></o:p></p></div><div><p class=MsoNormal>Best wishes <o:p></o:p></p></div><div><p class=MsoNormal>Gerry<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Fri, 16 Feb 2024, 16:50 Jean-Pierre Desrochers, <<a href="mailto:jpdesroc@oricom.ca">jpdesroc@oricom.ca</a>> wrote:<o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt'><div><div><p class=m6699767645608166082msoplaintext>Hi all,<o:p></o:p></p><p class=m6699767645608166082msoplaintext> <o:p></o:p></p><p class=m6699767645608166082msoplaintext>I’m using this type of stepup voltage regulator to generate +15vdc and +30vdc<o:p></o:p></p><p class=m6699767645608166082msoplaintext>From an incoming single +9vdc power adapter.<o:p></o:p></p><p class=m6699767645608166082msoplaintext>These BUCK’S converters generate very good regulated voltage outputs but I noticed<o:p></o:p></p><p class=m6699767645608166082msoplaintext>that on power up they ‘need’ to rise up to around +48vdc<o:p></o:p></p><p class=m6699767645608166082msoplaintext>Before settling down to their trimmed voltages.<o:p></o:p></p><p class=m6699767645608166082msoplaintext>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=m6699767645608166082msoplaintext>I tried putting a 16v zener diode in parallel with the trimmed +15vdc<o:p></o:p></p><p class=m6699767645608166082msoplaintext>But the BUCK goes wild (input current rise up to around 2.5 amp and stays there !!)<o:p></o:p></p><p class=m6699767645608166082msoplaintext>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=m6699767645608166082msoplaintext>But again the modules rise its input current to ‘try’ stabilize the regulation..<o:p></o:p></p><p class=m6699767645608166082msoplaintext>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=m6699767645608166082msoplaintext> <o:p></o:p></p><p class=m6699767645608166082msoplaintext>So.. I’m stuck with this problem..<o:p></o:p></p><p class=m6699767645608166082msoplaintext>Any possible solutions ???<o:p></o:p></p><p class=m6699767645608166082msoplaintext><img border=0 width=1302 height=1286 style='width:13.5625in;height:13.3958in' id="_x0000_i1025" src="cid:image001.jpg@01DA60CD.A2F81360"><o:p></o:p></p></div></div><p class=MsoNormal>________________________________________________________<br>This is the Synth-diy mailing list<br>Submit email to: <a href="mailto:Synth-diy@synth-diy.org" target="_blank">Synth-diy@synth-diy.org</a><br>View archive at: <a href="https://synth-diy.org/pipermail/synth-diy/" target="_blank">https://synth-diy.org/pipermail/synth-diy/</a><br>Check your settings at: <a href="https://synth-diy.org/mailman/listinfo/synth-diy" target="_blank">https://synth-diy.org/mailman/listinfo/synth-diy</a><br>Selling or trading? 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