> On Aug 24, 6:09 am, "Tom Del Rosso" <td...@att.net.invalid> wrote:
> >
> > > ftp://jjlarkin.lmi.net/BlockOsc.JPG
> >
> > How can that oscillate without feedback? I mean, would this
> > oscillate?
> >
>
> No, but that has no inductor in it...
It does, but it's not very recognizable in ASCII. The C's are supposed to
represent a coil.
--
Reply in group, but if emailing add one more
zero, and remove the last word.
Reply by fungus●August 28, 20092009-08-28
On Aug 24, 6:09=A0am, "Tom Del Rosso" <td...@att.net.invalid> wrote:
>
> That's a horrible circuit. Too many conflicting parameters depend on
> the value of R1. A proper blocking oscillator uses an RC time constant
> to set the rep rate, and a separate resistor to limit the base
> current.
>
> ftp://jjlarkin.lmi.net/BlockOsc.JPG
How can that oscillate without feedback? I mean, would this oscillate?
------------------------
|
|
|
R
R
R
R
|
|
|
|--------CCCCC------RRRRR------|
| |
| |
| -------
----- \ /
----- \ /
| \ /
| -------
| |
| |
| |
----------- -----------
------- -------
--- ---
--
Reply in group, but if emailing add one more
zero, and remove the last word.
Reply by fungus●August 12, 20092009-08-12
On Aug 12, 9:35=A0am, "Paul E. Schoen" <p...@peschoen.com> wrote:
>
> I would be careful about what you may read on that website. Just the name
> overunity is a red flag. Usually the claims of getting more power out tha=
n
> is put in are based on incorrect assumptions and bad measurements that
> don't take into account the effects of unusual waveforms and phase shift
> and cheap meters.
>
Oh, don't worry ... I'm not going to pay any attention
to all that that nonsense. I believe firmly in the laws
of physics.
Reply by Paul E. Schoen●August 12, 20092009-08-12
"fungus" <openglMYSOCKS@artlum.com> wrote in message
news:d45ed82f-6cc1-4ee7-8b91-4eb529bbf97d@c2g2000yqi.googlegroups.com...
On Aug 11, 10:23 pm, "bw" <bweg...@hotmail.com> wrote:
>
> Also, I've found a couple flash units that use a single AA cell to
> charge.
> Most use 2 AA cells, older and larger flash units used 6 volts. Older
> styles
> are also easier to reverse engineer and had larger transformers, making
> them
> easier to remove and re-use.
I've seen a lot of web sites using the flash
unit from disposable cameras to make JTs.
eg. http://www.overunity.com/index.php?topic=6942.0
They use them to light up fluorescent tubes,
400LEDs with a single AA battery, etc.
-------------------------------------------------
I would be careful about what you may read on that website. Just the name
overunity is a red flag. Usually the claims of getting more power out than
is put in are based on incorrect assumptions and bad measurements that
don't take into account the effects of unusual waveforms and phase shift
and cheap meters. I did not see any figures for efficiency of any of the
circuits shown, but I did see links for nonsense like a fan that charges
its own battery (unless it uses external wind power).
Paul
Reply by fungus●August 12, 20092009-08-12
On Aug 11, 10:23=A0pm, "bw" <bweg...@hotmail.com> wrote:
>
> Also, I've found a couple flash units that use a single AA cell to charge=
.
> Most use 2 AA cells, older and larger flash units used 6 volts. Older sty=
les
> are also easier to reverse engineer and had larger transformers, making t=
hem
> easier to remove and re-use.
I've seen a lot of web sites using the flash
unit from disposable cameras to make JTs.
eg. http://www.overunity.com/index.php?topic=3D6942.0
They use them to light up fluorescent tubes,
400LEDs with a single AA battery, etc.
Reply by bw●August 11, 20092009-08-11
"ehsjr" <ehsjr@NOSPAMverizon.net> wrote in message
news:2Ifgm.1688$Jg.556@nwrddc01.gnilink.net...
> David Eather wrote:
>> bw wrote:
>>
>>>
>>> All the cheap film cameras with flash have them. A local Goodwill store
>>> will have a box full of cheap chinese cameras. Take one apart. The flash
>>> unit just takes the 3 volts (from 2 AA cells) and fills a 100 uF
>>> capacitor to 330 volts. The switching xformer is about a 1/4 inch cube.
>>> There will also be a "pulse" transformer that is not in the power
>>> supply, it only flashes the xenon tube.
>>>
>>
>> Don't be tempted to power the camera in the dismantled state. The
>> capacitor can store power for a little while and will give you a serious
>> bite. (take a 5 or 10 minute delay after powering the circuit before you
>> start pulling it apart)
>>
>
> And short the capacitor with a screwdriver blade as soon as you
> get it far enough apart to do so. Otherwise, you might be in
> for an "exhilarating" experience. :-)
>
> Ed
Good advice. Newer caps seem to hold charge for days or longer. Older caps,
such as in Polaroids, leak faster. You can see the technology advance in
that the same voltage & capacity caps are now much smaller volume, and leak
less.
Charge drops slowly to about 50 volts, then holds there for much longer,
even weeks.
Also, I've found a couple flash units that use a single AA cell to charge.
Most use 2 AA cells, older and larger flash units used 6 volts. Older styles
are also easier to reverse engineer and had larger transformers, making them
easier to remove and re-use.
Reply by ehsjr●August 11, 20092009-08-11
David Eather wrote:
> bw wrote:
>
>> "fungus" <openglMYSOCKS@artlum.com> wrote in message
>> news:1fa52b8a-5e8b-44e1-931e-cd4ca416185e@k26g2000vbp.googlegroups.com...
>> On Aug 10, 9:24 am, ehsjr <eh...@NOSPAMverizon.net> wrote:
>>
>>> fungus wrote:
>>>
>>> <snip>
>>>
>>>> As an aside, would a transformer not work for a joule
>>>> thief?
>>>
>>> While it may have been called an "inductor" in the thread,
>>> that's just imprecise wording. Throughout the thread, it
>>> has always been a transformer in spite of however it has been
>>> worded, as long as it referred to the component in the joule
>>> thief circuit.
>>>
>>
>> I guess what I meant was, would a 'transformer'
>> which is designed for efficient conversion of
>> voltages be suitable for making efficient joule
>> thieves. Maybe the characteristics are completely
>> different.
>>
>> All the cheap film cameras with flash have them. A local Goodwill
>> store will have a box full of cheap chinese cameras. Take one apart.
>> The flash unit just takes the 3 volts (from 2 AA cells) and fills a
>> 100 uF capacitor to 330 volts. The switching xformer is about a 1/4
>> inch cube. There will also be a "pulse" transformer that is not in the
>> power supply, it only flashes the xenon tube.
>>
>>
>
> Don't be tempted to power the camera in the dismantled state. The
> capacitor can store power for a little while and will give you a serious
> bite. (take a 5 or 10 minute delay after powering the circuit before you
> start pulling it apart)
>
And short the capacitor with a screwdriver blade as soon as you
get it far enough apart to do so. Otherwise, you might be in
for an "exhilarating" experience. :-)
Ed
Reply by David Eather●August 11, 20092009-08-11
bw wrote:
> "fungus" <openglMYSOCKS@artlum.com> wrote in message
> news:1fa52b8a-5e8b-44e1-931e-cd4ca416185e@k26g2000vbp.googlegroups.com...
> On Aug 10, 9:24 am, ehsjr <eh...@NOSPAMverizon.net> wrote:
>> fungus wrote:
>>
>> <snip>
>>
>>> As an aside, would a transformer not work for a joule
>>> thief?
>> While it may have been called an "inductor" in the thread,
>> that's just imprecise wording. Throughout the thread, it
>> has always been a transformer in spite of however it has been
>> worded, as long as it referred to the component in the joule
>> thief circuit.
>>
>
> I guess what I meant was, would a 'transformer'
> which is designed for efficient conversion of
> voltages be suitable for making efficient joule
> thieves. Maybe the characteristics are completely
> different.
>
> All the cheap film cameras with flash have them. A local Goodwill store will
> have a box full of cheap chinese cameras. Take one apart. The flash unit
> just takes the 3 volts (from 2 AA cells) and fills a 100 uF capacitor to 330
> volts. The switching xformer is about a 1/4 inch cube. There will also be a
> "pulse" transformer that is not in the power supply, it only flashes the
> xenon tube.
>
>
Don't be tempted to power the camera in the dismantled state. The
capacitor can store power for a little while and will give you a serious
bite. (take a 5 or 10 minute delay after powering the circuit before you
start pulling it apart)
Reply by bw●August 10, 20092009-08-10
"fungus" <openglMYSOCKS@artlum.com> wrote in message
news:1fa52b8a-5e8b-44e1-931e-cd4ca416185e@k26g2000vbp.googlegroups.com...
On Aug 10, 9:24 am, ehsjr <eh...@NOSPAMverizon.net> wrote:
> fungus wrote:
>
> <snip>
>
> > As an aside, would a transformer not work for a joule
> > thief?
>
> While it may have been called an "inductor" in the thread,
> that's just imprecise wording. Throughout the thread, it
> has always been a transformer in spite of however it has been
> worded, as long as it referred to the component in the joule
> thief circuit.
>
I guess what I meant was, would a 'transformer'
which is designed for efficient conversion of
voltages be suitable for making efficient joule
thieves. Maybe the characteristics are completely
different.
All the cheap film cameras with flash have them. A local Goodwill store will
have a box full of cheap chinese cameras. Take one apart. The flash unit
just takes the 3 volts (from 2 AA cells) and fills a 100 uF capacitor to 330
volts. The switching xformer is about a 1/4 inch cube. There will also be a
"pulse" transformer that is not in the power supply, it only flashes the
xenon tube.