[sdiy] Vanilla electronics question
Tony Mowbray
tmowbray at ihug.com.au
Mon Feb 19 17:04:03 CET 2024
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.But then again, I could be way offRegards Tony,Sent from Samsung tablet.
-------- Original message --------From: René Schmitz <synth at schmitzbits.de> Date: 19/2/24 23:41 (GMT+10:00) To: synth-diy at synth-diy.org Subject: Re: [sdiy] Vanilla electronics question
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.
The reverse leakage current of this device would be in the order
where you can see the LED light up. (0.4mA)
IMO it's an attempt to build a current limit.
Best,
René
Am 18.02.2024 um 00:34 schrieb Mike
Bryant:
P {margin-top:0;margin-bottom:0;}
Pure guess ... more like a breakdown current. Sort of like a
Zener ... but not quite.
Conversely there may be a better explanation ... just I can't
think of one.
From: Chris
McDowell <declareupdate at gmail.com>
Sent: 17 February 2024 23:16
To: Mike Bryant <mbryant at futurehorizons.com>
Cc: grant musictechnologiesgroup.com <grant at musictechnologiesgroup.com>;
Rutger Vlek <rutgervlek at gmail.com>;
SDIY List <synth-diy at synth-diy.org>
Subject: Re: [sdiy] Vanilla electronics question
wacky. Is it the leakage current of D1 that allows
C1 to do anything in the first place?
Cheers,
Chris
On Feb 17, 2024, at 4:59 PM, Mike
Bryant <mbryant at futurehorizons.com>
wrote:
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.
As for it not working, it's possibly because D1 is
borked from being used like this.
From: Synth-diy <synth-diy-bounces at synth-diy.org>
on behalf of Rutger Vlek via Synth-diy <synth-diy at synth-diy.org>
Sent: 17 February 2024 18:35
To: grant musictechnologiesgroup.com <grant at musictechnologiesgroup.com>
Cc: SDIY List <Synth-diy at synth-diy.org>
Subject: Re: [sdiy] Vanilla electronics
question
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.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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