<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body dir="auto"><div dir="auto">Actually I think it runs as an oscillator so the operation of the LEDs is pulsed to allow high current for a short period of time.</div><div dir="auto"><br></div><div dir="auto">But then again, I could be way off</div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto"><br></div><div id="composer_signature" dir="auto"><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><div style="font-size:85%;color:#575757">Regards Tony,</div><div style="font-size:85%;color:#575757"><br></div><div style="font-size:85%;color:#575757">Sent from Samsung tablet.</div></div><div dir="auto"><br></div><div><br></div><div align="left" dir="auto" style="font-size:100%;color:#000000"><div>-------- Original message --------</div><div>From: René Schmitz <synth@schmitzbits.de> </div><div>Date: 19/2/24 23:41 (GMT+10:00) </div><div>To: synth-diy@synth-diy.org </div><div>Subject: Re: [sdiy] Vanilla electronics question </div><div><br></div></div>
<p><br>
</p>
<p>Only: SS16 has 60V reverse voltage capability. Probably with
considerable slack until it actually breaks down. I can't see how
it would get into a breakdown with 12V.</p>
<p><br>
</p>
<p><br>
</p>
<p>The reverse leakage current of this device would be in the order
where you can see the LED light up. (0.4mA)</p>
<p>IMO it's an attempt to build a current limit.</p>
<p><br>
</p>
<p>Best,</p>
<p> René<br>
</p>
<p><br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">Am 18.02.2024 um 00:34 schrieb Mike
Bryant:<br>
</div>
<blockquote type="cite">
<style style="display:none;" type="text/css">P {margin-top:0;margin-bottom:0;}</style>
<div style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
Pure guess ... more like a breakdown current. Sort of like a
Zener ... but not quite.</div>
<div style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
<br>
</div>
<div style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">
Conversely there may be a better explanation ... just I can't
think of one.<br>
</div>
<hr tabindex="-1" style="display:inline-block;width:98%">
<div dir="ltr" id="divRplyFwdMsg"><font color="#000000" face="Calibri, sans-serif" style="font-size:11pt"><b>From:</b> Chris
McDowell <a href="mailto:declareupdate@gmail.com" class="moz-txt-link-rfc2396E"><declareupdate@gmail.com></a><br>
<b>Sent:</b> 17 February 2024 23:16<br>
<b>To:</b> Mike Bryant <a href="mailto:mbryant@futurehorizons.com" class="moz-txt-link-rfc2396E"><mbryant@futurehorizons.com></a><br>
<b>Cc:</b> grant musictechnologiesgroup.com <a href="mailto:grant@musictechnologiesgroup.com" class="moz-txt-link-rfc2396E"><grant@musictechnologiesgroup.com></a>;
Rutger Vlek <a href="mailto:rutgervlek@gmail.com" class="moz-txt-link-rfc2396E"><rutgervlek@gmail.com></a>;
SDIY List <a href="mailto:synth-diy@synth-diy.org" class="moz-txt-link-rfc2396E"><synth-diy@synth-diy.org></a><br>
<b>Subject:</b> Re: [sdiy] Vanilla electronics question</font>
<div> </div>
</div>
<div dir="auto">wacky. Is it the leakage current of D1 that allows
C1 to do anything in the first place?
<div><br id="x_lineBreakAtBeginningOfSignature">
<div dir="ltr">Cheers,
<div>Chris </div>
</div>
<div dir="ltr"><br>
<blockquote type="cite">On Feb 17, 2024, at 4:59 PM, Mike
Bryant <a href="mailto:mbryant@futurehorizons.com" class="moz-txt-link-rfc2396E"><mbryant@futurehorizons.com></a>
wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)" class="x_elementToProof">
Yes fairly sure D1 is operating in some form of
avalanche mode, turning the LEDs on for a short while
before it recovers and turns them off again. Could be
at 100Hz, 1Hz or even 0.1Hz though, depends on C1.</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)" class="x_elementToProof">
<br>
</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)" class="x_elementToProof">
As for it not working, it's possibly because D1 is
borked from being used like this.<br>
</div>
<hr style="display:inline-block; width:98%" tabindex="-1">
<div dir="ltr" id="x_divRplyFwdMsg"><font color="#000000" face="Calibri, sans-serif" style="font-size:11pt"><b>From:</b> Synth-diy <a href="mailto:synth-diy-bounces@synth-diy.org" class="moz-txt-link-rfc2396E"><synth-diy-bounces@synth-diy.org></a>
on behalf of Rutger Vlek via Synth-diy <a href="mailto:synth-diy@synth-diy.org" class="moz-txt-link-rfc2396E"><synth-diy@synth-diy.org></a><br>
<b>Sent:</b> 17 February 2024 18:35<br>
<b>To:</b> grant musictechnologiesgroup.com <a href="mailto:grant@musictechnologiesgroup.com" class="moz-txt-link-rfc2396E"><grant@musictechnologiesgroup.com></a><br>
<b>Cc:</b> SDIY List <a href="mailto:Synth-diy@synth-diy.org" class="moz-txt-link-rfc2396E"><Synth-diy@synth-diy.org></a><br>
<b>Subject:</b> Re: [sdiy] Vanilla electronics
question</font>
<div> </div>
</div>
<div>
<div dir="ltr">
<div dir="ltr">
<div>Here's a schematic of the circuit. These are
really all the components. The entire PCB is
really no more than twice the size of my finger
tip. The capacitor value is unknown.</div>
<div><br>
</div>
<div><image.png></div>
<br>
</div>
<br>
<div class="x_x_gmail_quote">
<div class="x_x_gmail_attr" dir="ltr">Op za 17 feb
2024 om 18:58 schreef grant <a href="http://musictechnologiesgroup.com">
musictechnologiesgroup.com</a> <<a class="moz-txt-link-freetext" href="mailto:grant@musictechnologiesgroup.com">grant@musictechnologiesgroup.com</a>>:<br>
</div>
<blockquote style="margin:0px 0px 0px 0.8ex; border-left:1px solid rgb(204,204,204); padding-left:1ex" class="x_x_gmail_quote">
<div class="x_x_msg2538923805455999034">
<div>
<div>Once you all get consensus on the
circuit, any chance us in the peanut gallery
can get some kind of schematic so we can
follow along? Thanks!</div>
<div><br>
</div>
<div>GB</div>
<div style="clear:both"><br>
</div>
<div><br>
</div>
<div>
<div>------ Original Message ------</div>
<div>From "Rutger Vlek via Synth-diy" <<a class="moz-txt-link-freetext" href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a>></div>
<div>To "SDIY List" <<a class="moz-txt-link-freetext" href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a>></div>
<div>Date 2/17/2024 7:48:43 AM</div>
<div>Subject [sdiy] Vanilla electronics
question</div>
</div>
<div><br>
</div>
<div id="x_x_m_2538923805455999034xa788abb1a9f1404">
<blockquote class="x_x_m_2538923805455999034cite2" type="cite">
<div dir="ltr">Dear list,
<div><br>
</div>
<div>Against my wishes, I'm working on
repairing my eBike's rear light,
instead of building something synth
related. However, I'm stumbled by a
seemingly simple circuit that just
does not behave as I expected. Of
course I considered buying a new rear
light, but for the sake of the planet
(and my own knowledge gathering), I'm
trying to revive the original one.</div>
<div><br>
</div>
<div>The circuit is simple, I'll try to
describe it. Positive voltage
(appox. 12V) from the bike's battery
enters two red, parallelled power LEDs
(in forward direction), goes through a
150 ohm resistor, and then through
what seems like a Schottky diode (SMD
package labelled SS16) in reverse (!),
non-conducting direction to ground.
The point before the SS16 is also
connected via a capacitor to the
positive supply.</div>
<div><br>
</div>
<div>I replaced the LEDs and they are
testing fine now (didn't before). From
the start I assumed the SS16 (presumed
Schottky diode) to be there for
reverse voltage protection, until
today... when I looked at the
direction in which it's placed.
Moreover, the resistance and power
dissipation capacity of the resistor
don't seem to fit a traditional LED
circuit. In other words, the resistor
would run the LEDs very close or over
their maximum current rating, and
would burn out due to the heat it had
to dissipate while doing so.</div>
<div><br>
</div>
<div>So....can anyone tell me, what is
this circuit? If I had to guess, it's
either:</div>
<div>(1) an attempt at a traditional LED
circuit by someone who messed-up badly</div>
<div>(2) some kind of switching voltage
regulator (the rear light indicates to
be capable of handling a supply
anywhere between 6V to 12V). So I'm
guessing it's the latter.</div>
<div><br>
</div>
<div>If moderation feels this is way off
topic, I can completely understand.
Although I'm interested to learn about
this circuit, as it perhaps could find
its way into synthesizers too.</div>
<div><br>
</div>
<div>Rutger</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
</div>
</blockquote>
</div>
</div>
</div>
</blockquote>
</div>
</div>
</div>
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<pre wrap="" class="moz-quote-pre">________________________________________________________
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</blockquote>
<pre cols="72" class="moz-signature">--
--
<a href="mailto:synth@schmitzbits.de" class="moz-txt-link-abbreviated moz-txt-link-freetext">synth@schmitzbits.de</a>
<a href="http://schmitzbits.de" class="moz-txt-link-freetext">http://schmitzbits.de</a></pre>
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