[sdiy] Vanilla electronics question

[Rutger Vlek]

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.

[image: image.png]

Op za 17 feb 2024 om 18:58 schreef grant musictechnologiesgroup.com <
grant at musictechnologiesgroup.com>:

> 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!
>
> GB
>
>
> ------ Original Message ------
> From "Rutger Vlek via Synth-diy" <Synth-diy at synth-diy.org>
> To "SDIY List" <Synth-diy at synth-diy.org>
> Date 2/17/2024 7:48:43 AM
> Subject [sdiy] Vanilla electronics question
>
> Dear list,
>
> 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.
>
> 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.
>
> 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.
>
> So....can anyone tell me, what is this circuit? If I had to guess, it's
> either:
> (1) an attempt at a traditional LED circuit by someone who messed-up badly
> (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.
>
> 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.
>
> Rutger
>
>
>
>
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