2 component negative feedback oscillator and voltage "multip

R

Robert Baer

Guest
Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.
Go buy the Dollar Tree LED Flashlight and Lantern Combination SKU:
286458 and see (do not forget it needs one AA cell).


Version 4
SHEET 1 5945676 13421556
WIRE 2080 -592 1648 -592
WIRE 2080 -560 2080 -592
WIRE 2080 -496 2048 -496
WIRE 2176 -496 2080 -496
WIRE 1648 -480 1648 -592
WIRE 2048 -448 2048 -496
WIRE 2176 -384 2176 -496
WIRE 1648 -368 1648 -400
WIRE 2048 -336 2048 -368
WIRE 2112 -336 2048 -336
WIRE 2176 -240 2176 -288
WIRE 2176 -240 2080 -240
WIRE 2080 -192 2080 -240
FLAG 1648 -368 0
FLAG 2080 -192 0
SYMBOL voltage 1648 -496 R0
WINDOW 3 -25 166 Left 2
WINDOW 123 24 44 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value PULSE(0 1.5 10n 1n 1n 1 2 1)
SYMATTR Value2 AC 1.5
SYMATTR InstName V1
SYMBOL npn 2112 -384 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL ind 2064 -352 R180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L1
SYMATTR Value 5.6m
SYMATTR SpiceLine Ipk=0.9 Rser=2.2 Rpar=173693 Cpar=0
SYMBOL LED 2096 -496 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value NSCW100
SYMATTR Description Diode
SYMATTR Type diode
TEXT 1928 -368 Left 2 ;2.2 ohms
TEXT 1622 -296 Left 2 !.tran 0 5 0 1u startup
 
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
<robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.
Click to expand...

Maybe it's not a transistor.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
<robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.
Click to expand...

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.




--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.
Click to expand...
Standard NPN, i think.
Things seem to not oscillate in Spice.
 
On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.
Click to expand...

The original circuit oscillates if you put 100k from supply to base. But
only puts 20uA RMS through the LED used
 
On Sat, 25 Jan 2020 23:35:25 -0500, bitrex <user@example.net> wrote:

On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.




The original circuit oscillates if you put 100k from supply to base. But
only puts 20uA RMS through the LED used
Click to expand...

The LED is back-biased.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.
Click to expand...

With lossless L this is about 95% efficient:

Version 4
SHEET 1 5945676 13421556
WIRE 2160 -592 1680 -592
WIRE 2160 -512 2160 -592
WIRE 1680 -480 1680 -592
WIRE 1904 -384 1904 -496
WIRE 1680 -368 1680 -400
WIRE 2160 -368 2160 -432
WIRE 2336 -368 2160 -368
WIRE 2160 -320 2160 -368
WIRE 1904 -224 1904 -304
WIRE 1968 -224 1904 -224
WIRE 2080 -224 2032 -224
WIRE 2336 -208 2336 -368
WIRE 2160 -160 2160 -240
WIRE 1904 -112 1904 -224
WIRE 1952 -112 1904 -112
WIRE 2080 -112 2080 -224
WIRE 2080 -112 2032 -112
WIRE 2096 -112 2080 -112
WIRE 2160 0 2160 -64
WIRE 2336 0 2336 -144
FLAG 1680 -368 0
FLAG 2160 0 0
FLAG 2336 0 0
FLAG 1904 -496 0
SYMBOL voltage 1680 -496 R0
WINDOW 3 -394 13 Left 2
WINDOW 123 48 57 Left 2
WINDOW 39 0 0 Left 2
WINDOW 0 72 26 Left 2
SYMATTR Value PULSE(0 1.5 10n 1n 1n 1 2 1)
SYMATTR Value2 AC 1.5
SYMATTR InstName V1
SYMBOL LED 2320 -208 R0
SYMATTR InstName D1
SYMATTR Value NSCW100
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL ind2 2144 -528 R0
SYMATTR InstName L2
SYMATTR Value 47Âľ
SYMBOL ind2 1920 -288 R180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L1
SYMATTR Value 47Âľ
SYMBOL npn 2096 -160 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL ind2 2144 -336 R0
SYMATTR InstName L3
SYMATTR Value 47Âľ
SYMBOL res 2048 -128 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 37 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 100
SYMBOL cap 2032 -240 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 470p
TEXT 1288 -448 Left 2 !.tran 0 5 0 1u startup uic
TEXT 1936 -336 Left 2 !K L1 L2 L3 0.99
 
On 1/26/20 1:06 AM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 23:35:25 -0500, bitrex <user@example.net> wrote:

On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.




The original circuit oscillates if you put 100k from supply to base. But
only puts 20uA RMS through the LED used

The LED is back-biased.
Click to expand...

It must be sucking the light _in_!
 
On Sun, 26 Jan 2020 01:09:29 -0500, bitrex <user@example.net> wrote:

On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.



With lossless L this is about 95% efficient:

Version 4
SHEET 1 5945676 13421556
WIRE 2160 -592 1680 -592
WIRE 2160 -512 2160 -592
WIRE 1680 -480 1680 -592
WIRE 1904 -384 1904 -496
WIRE 1680 -368 1680 -400
WIRE 2160 -368 2160 -432
WIRE 2336 -368 2160 -368
WIRE 2160 -320 2160 -368
WIRE 1904 -224 1904 -304
WIRE 1968 -224 1904 -224
WIRE 2080 -224 2032 -224
WIRE 2336 -208 2336 -368
WIRE 2160 -160 2160 -240
WIRE 1904 -112 1904 -224
WIRE 1952 -112 1904 -112
WIRE 2080 -112 2080 -224
WIRE 2080 -112 2032 -112
WIRE 2096 -112 2080 -112
WIRE 2160 0 2160 -64
WIRE 2336 0 2336 -144
FLAG 1680 -368 0
FLAG 2160 0 0
FLAG 2336 0 0
FLAG 1904 -496 0
SYMBOL voltage 1680 -496 R0
WINDOW 3 -394 13 Left 2
WINDOW 123 48 57 Left 2
WINDOW 39 0 0 Left 2
WINDOW 0 72 26 Left 2
SYMATTR Value PULSE(0 1.5 10n 1n 1n 1 2 1)
SYMATTR Value2 AC 1.5
SYMATTR InstName V1
SYMBOL LED 2320 -208 R0
SYMATTR InstName D1
SYMATTR Value NSCW100
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL ind2 2144 -528 R0
SYMATTR InstName L2
SYMATTR Value 47ľ
SYMBOL ind2 1920 -288 R180
WINDOW 0 36 80 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName L1
SYMATTR Value 47ľ
SYMBOL npn 2096 -160 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL ind2 2144 -336 R0
SYMATTR InstName L3
SYMATTR Value 47ľ
SYMBOL res 2048 -128 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 37 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 100
SYMBOL cap 2032 -240 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 470p
TEXT 1288 -448 Left 2 !.tran 0 5 0 1u startup uic
TEXT 1936 -336 Left 2 !K L1 L2 L3 0.99
Click to expand...

That needs a 3-winding transformer and doesn't start reliably. It has
a do-nothing state.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
On 1/26/20 10:56 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 26 Jan 2020 01:09:29 -0500, bitrex <user@example.net> wrote:

On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.



With lossless L this is about 95% efficient:
Click to expand...

<snip>

That needs a 3-winding transformer and doesn't start reliably. It has
a do-nothing state.
Click to expand...

All one-transistor positive feedback oscillators have a "do nothing'
state my dude...

I don't know any 1 winding or 2 winding one-transistor oscillators that
have very good efficiency driving an LED, the current ramp needs to be
well-controlled and the transistor driven hard on and off. A sine
oscillator won't do that, a naive blocking oscillator doesn't do it
either and taking the LED output from the transistor collector shits it
up. Rectifying and filtering would improve it but then you burn power in
the rectifier.
 
On Sun, 26 Jan 2020 15:28:55 -0500, bitrex <user@example.net> wrote:

On 1/26/20 10:56 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 26 Jan 2020 01:09:29 -0500, bitrex <user@example.net> wrote:

On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.



With lossless L this is about 95% efficient:


snip

That needs a 3-winding transformer and doesn't start reliably. It has
a do-nothing state.

All one-transistor positive feedback oscillators have a "do nothing'
state my dude...
Click to expand...

Not so. Any decently-designed oscillator will always oscillate when
power is present, and has no hang state. Quench it and it starts back
up.

I don't know any 1 winding or 2 winding one-transistor oscillators that
have very good efficiency driving an LED, the current ramp needs to be
well-controlled and the transistor driven hard on and off. A sine
oscillator won't do that, a naive blocking oscillator doesn't do it
either and taking the LED output from the transistor collector shits it
up. Rectifying and filtering would improve it but then you burn power in
the rectifier.
Click to expand...

A good blocking oscillator puts most of the cycle energy into the LED.
Neither ideal inductors nor switches dissipate power, and it's not
hard to get close to ideal. And sensible blocking oscillators always
oscillate.

But there are cheap chips that power an LED from one cell and only
need one inductor.








--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"
 
On Saturday, January 25, 2020 at 1:18:30 PM UTC-5, jla...@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.
Click to expand...

Probably not. The solar lights & cheesy flashlights I've dissected
use little 3 or 4-pin boost converters, one inductor, and not much
else.

QX5252F is one such beast, and the S-8351 series is another.
https://www.digikey.com/product-detail/en/ablic-u-s-a-inc/S-8351B33MA-J4ST2G/S-8351B33MA-J4ST2G-ND/1661764

Cheers,
James Arthur
 
On Saturday, January 25, 2020 at 2:50:03 AM UTC-5, Robert Baer wrote:
Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.
Go buy the Dollar Tree LED Flashlight and Lantern Combination SKU:
286458 and see (do not forget it needs one AA cell).
Click to expand...

I don't seem unijunction transistors much these days. I would think they'd do pretty well for this sort of circuit. Sort of a single transistor 555 timer.

I have to say no one has been able to explain to me why they disappeared.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
 
On 1/26/20 4:45 PM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 26 Jan 2020 15:28:55 -0500, bitrex <user@example.net> wrote:

On 1/26/20 10:56 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 26 Jan 2020 01:09:29 -0500, bitrex <user@example.net> wrote:

On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.



With lossless L this is about 95% efficient:


snip

That needs a 3-winding transformer and doesn't start reliably. It has
a do-nothing state.

All one-transistor positive feedback oscillators have a "do nothing'
state my dude...

Not so. Any decently-designed oscillator will always oscillate when
power is present, and has no hang state. Quench it and it starts back
up.


I don't know any 1 winding or 2 winding one-transistor oscillators that
have very good efficiency driving an LED, the current ramp needs to be
well-controlled and the transistor driven hard on and off. A sine
oscillator won't do that, a naive blocking oscillator doesn't do it
either and taking the LED output from the transistor collector shits it
up. Rectifying and filtering would improve it but then you burn power in
the rectifier.

A good blocking oscillator puts most of the cycle energy into the LED.
Neither ideal inductors nor switches dissipate power, and it's not
hard to get close to ideal. And sensible blocking oscillators always
oscillate.
Click to expand...

The list that comes up when you search "high efficiency Joule thief" is
long, but I've found that actual numbers whether simulated or
experimental are pretty thin on the ground. In a real circuit with
small-ish value of inductance to get the oscillation frequency up the
core is always going to be going into saturation on every cycle I dunno
how that could be very efficient.

But there are cheap chips that power an LED from one cell and only
need one inductor.
Click to expand...

This one works great it can do a string of 7 LEDs with PWM dimming:

<https://www.newark.com/on-semiconductor/cat4237td-gt3/white-led-driver-boost-tsot-23/dp/08R5269>

It can even be pressed into service as a CM flyback controller for
well-behaved secondary loads
 
jlarkin@highlandsniptechnology.com wrote...
Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192
Click to expand...

The ZXSC380 circuit has only three parts, a sot-23
"transistor", an inductor and LED. The same three
parts in the .asc circuit are arraigned differently,
but as you pointed out, the LED is back biased, and
cannot work as drawn. So, the reverse engineering
on the Dollar Tree LED Flashlight must be in error.
The ZXSC380 likely costs pennies, in high volumes.




--
Thanks,
- Win
 
bitrex wrote:
On 1/26/20 10:56 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 26 Jan 2020 01:09:29 -0500, bitrex <user@example.net> wrote:

On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

     Problems are: Spice version does not oscillate, and Spice
LED voltage
is not 3V.

Maybe it's not a transistor.



    Standard NPN, i think.
    Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192


but not that exact circuit.



With lossless L this is about 95% efficient:


snip

That needs a 3-winding transformer and doesn't start reliably. It has
a do-nothing state.

All one-transistor positive feedback oscillators have a "do nothing'
state my dude...

I don't know any 1 winding or 2 winding one-transistor oscillators that
have very good efficiency driving an LED, the current ramp needs to be
well-controlled and the transistor driven hard on and off. A sine
oscillator won't do that, a naive blocking oscillator doesn't do it
either and taking the LED output from the transistor collector shits it
up. Rectifying and filtering would improve it but then you burn power in
the rectifier.
Click to expand...
What about the joule thief? Seems to run until the cell is damn near
dead.
 
jlarkin@highlandsniptechnology.com wrote:
On Sun, 26 Jan 2020 15:28:55 -0500, bitrex <user@example.net> wrote:

On 1/26/20 10:56 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 26 Jan 2020 01:09:29 -0500, bitrex <user@example.net> wrote:

On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.



With lossless L this is about 95% efficient:


snip

That needs a 3-winding transformer and doesn't start reliably. It has
a do-nothing state.

All one-transistor positive feedback oscillators have a "do nothing'
state my dude...

Not so. Any decently-designed oscillator will always oscillate when
power is present, and has no hang state. Quench it and it starts back
up.


I don't know any 1 winding or 2 winding one-transistor oscillators that
have very good efficiency driving an LED, the current ramp needs to be
well-controlled and the transistor driven hard on and off. A sine
oscillator won't do that, a naive blocking oscillator doesn't do it
either and taking the LED output from the transistor collector shits it
up. Rectifying and filtering would improve it but then you burn power in
the rectifier.

A good blocking oscillator puts most of the cycle energy into the LED.
Neither ideal inductors nor switches dissipate power, and it's not
hard to get close to ideal. And sensible blocking oscillators always
oscillate.

But there are cheap chips that power an LED from one cell and only
need one inductor.
* ...very much like the one you cited from Zetex.
Click to expand...
 
Winfield Hill wrote:
jlarkin@highlandsniptechnology.com wrote...

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

The ZXSC380 circuit has only three parts, a sot-23
"transistor", an inductor and LED. The same three
parts in the .asc circuit are arraigned differently,
but as you pointed out, the LED is back biased, and
cannot work as drawn. So, the reverse engineering
on the Dollar Tree LED Flashlight must be in error.
The ZXSC380 likely costs pennies, in high volumes.




I messed on the trace-out to schematic. Sorry.
Click to expand...
 
On 1/27/20 1:39 PM, bitrex wrote:
On 1/27/20 1:13 PM, Robert Baer wrote:
bitrex wrote:
On 1/26/20 10:56 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 26 Jan 2020 01:09:29 -0500, bitrex <user@example.net> wrote:

On 1/25/20 9:39 PM, jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

     Problems are: Spice version does not oscillate, and Spice
LED voltage
is not 3V.

Maybe it's not a transistor.



    Standard NPN, i think.
    Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192


but not that exact circuit.



With lossless L this is about 95% efficient:


snip

That needs a 3-winding transformer and doesn't start reliably. It has
a do-nothing state.

All one-transistor positive feedback oscillators have a "do nothing'
state my dude...

I don't know any 1 winding or 2 winding one-transistor oscillators
that have very good efficiency driving an LED, the current ramp needs
to be well-controlled and the transistor driven hard on and off. A
sine oscillator won't do that, a naive blocking oscillator doesn't do
it either and taking the LED output from the transistor collector
shits it up. Rectifying and filtering would improve it but then you
burn power in the rectifier.
   What about the joule thief? Seems to run until the cell is damn
near dead.


Ya, it can boost a very low voltage that doesn't automatically imply its
very efficient at transferring energy for any given combination of
components and supply voltage. The very simple ones with one coupled
inductor and a resistor I don't know how they would achieve very high
efficiency (>90%) AFAIK they operate by allowing the transformer core to
saturate that's not efficient.

Could probably cut-and-try component values to get it in the 80s but
performance would depend heavily on the properties of the inductor and LED.

There are lots of variations like:

https://homemade-circuits.com/wp-content/uploads/2012/01/LEDDriver-1.png

and:

https://devopedia.org/images/article/181/7660.1559297408.png

Some may be inherently better than others.
Click to expand...

If it were easy to make a highly efficient 1 transistor oscillator/LED
driver that was highly efficient and somewhat insensitive to supply
variation, inductor properties and LED type I don't think they could
make much $$$ selling 3 terminal integrated boost converters for driving
single LEDs for 75 cent in singles
 
jlarkin@highlandsniptechnology.com wrote:
On Sat, 25 Jan 2020 18:19:04 -0800, Robert Baer
robertbaer@localnet.com> wrote:

jlarkin@highlandsniptechnology.com wrote:
On Fri, 24 Jan 2020 23:49:53 -0800, Robert Baer
robertbaer@localnet.com> wrote:

Problems are: Spice version does not oscillate, and Spice LED voltage
is not 3V.

Maybe it's not a transistor.



Standard NPN, i think.
Things seem to not oscillate in Spice.

That circuit would never oscillate. If it did, it would pump energy
*into* the battery.

Might be something like this:

https://www.digikey.com/product-detail/en/diodes-incorporated/ZXSC380FHTA/ZXSC380FHCT-ND/1767192

but not that exact circuit.
Click to expand...
I took some measurements and note that indeed you are correct, except
the circuit on page 5 of the ZXSC380 is the one i cited.
Thanks for the part type and data sheet.
 
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