On Tuesday, June 26, 2018 at 5:45:49 PM UTC+2, John Larkin wrote:
> On Mon, 25 Jun 2018 19:10:55 -0400, Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>
> >On 06/25/18 13:03, John Larkin wrote:
> >> On Sun, 24 Jun 2018 12:05:48 -0400, Phil Hobbs
> >> <pcdhSpamMeSenseless@electrooptical.net> wrote:
> >>
> >>> On 06/24/18 10:17, John Larkin wrote:
> >>>> On Sun, 24 Jun 2018 00:59:15 -0700 (PDT), pcdhobbs@gmail.com wrote:
> >>>>
> >>>>>> It's also faster (near zero t_rr), because it's never saturated.
> >>>>>
> >>>>> Falls apart at low current though, on account of beta rolling off. The 'diode-connected transistor' is the world's simplest feedback amp. I've seen them oscillate, too--that was a weird one to debug.
> >>>>>
> >>>>> Cheers
> >>>>>
> >>>>> Phil Hobbs
> >>>>
> >>>> I'll never get any sleep if you keep inventing horrors like that.
> >>>>
> >>>
> >>> I did a proof of concept for a long range IR remote control for Samsung
> >>> some years back--it got them a factor of three increase in range, which
> >>> they were happy about. The main issue, interestingly, was avoiding the
> >>> forest of optical spurs put out by electronic-ballast fluorescent
> >>> lights. The biggest headache was the spectral lines from the mercury
> >>> emission, which (near the ends of the tubes) have important harmonics of
> >>> 40 kHz that extend out past a megahertz. So naturally I built them what
> >>> was basically an AM radio, complete with a 455-kHz ceramic IF filter,
> >>> and used an interference filter to select an optical band with no
> >>> emission lines.
> >>>
> >>> The point of this story is that the low frequency bias loop used five
> >>> diode-connected BFT25As in series, to give a wide operating range
> >>> without adding much shot noise. It worked fine at high currents, but
> >>> just crapped out below about 5 nA--the diodes stopped behaving like
> >>> diodes.
> >>>
> >>> It turned out that the 5-GHz BFT25As were slowing down so much at those
> >>> low currents that they ran out of gain at 1 MHz. I switched to using
> >>> the CB junctions instead, and the circuit started working.
> >>>
> >>> With a sub-optimal layout, a diode-connected BFT25A can oscillate above
> >>> about 100 uA I_C.
> >>>
> >>> Cheers
> >>>
> >>> Phil Hobbs
> >>
> >> I did some work on Fourier Transform Mass Spectroscopy. The old
> >> electronics had been design by a couple of chemists, and the spectrum
> >> was dominated by junk from fluorescent lights. The 30 dB excess
> >> wideband noise floor did make that look not as bad as it really was.
> >>
> >> Sadly, Agilent acquired Varian and killed off both the NMR and FTMS
> >> operations.
> >>
> >>
> >Yeah, that's why I sell a lot of photon budgets. You don't know how
> >you're doing till you know how good it _could_ be.
> >
> >Cheers
> >
> >Phil Hobbs
>
> I had about convinced myself that we could detect a single molecule in
> orbit in the machine, but then Agilent killed the whole thing.
>
> Once we did single molecules, that would be the end of it. No point in
> getting better from there.
"Molecule" is rather broad concept. Being able to detect a helium molecule - actually an ionised helium molecule - is nice, but the two stage mass spectrometer that I worked on (briefly) in 1992 was supposed to detect ionised protein molecules, and their fragmentation products.
Very precise molecular weights - good enough to allow you to keep track of the mass defects in the atoms in the molecule - were promised (and probably delivered).
--
Bill Sloman, Sydney
Reply by Phil Hobbs●June 25, 20182018-06-25
On 06/25/18 13:03, John Larkin wrote:
> On Sun, 24 Jun 2018 12:05:48 -0400, Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>
>> On 06/24/18 10:17, John Larkin wrote:
>>> On Sun, 24 Jun 2018 00:59:15 -0700 (PDT), pcdhobbs@gmail.com wrote:
>>>
>>>>> It's also faster (near zero t_rr), because it's never saturated.
>>>>
>>>> Falls apart at low current though, on account of beta rolling off. The 'diode-connected transistor' is the world's simplest feedback amp. I've seen them oscillate, too--that was a weird one to debug.
>>>>
>>>> Cheers
>>>>
>>>> Phil Hobbs
>>>
>>> I'll never get any sleep if you keep inventing horrors like that.
>>>
>>
>> I did a proof of concept for a long range IR remote control for Samsung
>> some years back--it got them a factor of three increase in range, which
>> they were happy about. The main issue, interestingly, was avoiding the
>> forest of optical spurs put out by electronic-ballast fluorescent
>> lights. The biggest headache was the spectral lines from the mercury
>> emission, which (near the ends of the tubes) have important harmonics of
>> 40 kHz that extend out past a megahertz. So naturally I built them what
>> was basically an AM radio, complete with a 455-kHz ceramic IF filter,
>> and used an interference filter to select an optical band with no
>> emission lines.
>>
>> The point of this story is that the low frequency bias loop used five
>> diode-connected BFT25As in series, to give a wide operating range
>> without adding much shot noise. It worked fine at high currents, but
>> just crapped out below about 5 nA--the diodes stopped behaving like
>> diodes.
>>
>> It turned out that the 5-GHz BFT25As were slowing down so much at those
>> low currents that they ran out of gain at 1 MHz. I switched to using
>> the CB junctions instead, and the circuit started working.
>>
>> With a sub-optimal layout, a diode-connected BFT25A can oscillate above
>> about 100 uA I_C.
>>
>> Cheers
>>
>> Phil Hobbs
>
> I did some work on Fourier Transform Mass Spectroscopy. The old
> electronics had been design by a couple of chemists, and the spectrum
> was dominated by junk from fluorescent lights. The 30 dB excess
> wideband noise floor did make that look not as bad as it really was.
>
> Sadly, Agilent acquired Varian and killed off both the NMR and FTMS
> operations.
>
>
Yeah, that's why I sell a lot of photon budgets. You don't know how
you're doing till you know how good it _could_ be.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.nethttp://hobbs-eo.com
Reply by John Larkin●June 25, 20182018-06-25
On Sun, 24 Jun 2018 12:05:48 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
>On 06/24/18 10:17, John Larkin wrote:
>> On Sun, 24 Jun 2018 00:59:15 -0700 (PDT), pcdhobbs@gmail.com wrote:
>>
>>>> It's also faster (near zero t_rr), because it's never saturated.
>>>
>>> Falls apart at low current though, on account of beta rolling off. The 'diode-connected transistor' is the world's simplest feedback amp. I've seen them oscillate, too--that was a weird one to debug.
>>>
>>> Cheers
>>>
>>> Phil Hobbs
>>
>> I'll never get any sleep if you keep inventing horrors like that.
>>
>
>I did a proof of concept for a long range IR remote control for Samsung
>some years back--it got them a factor of three increase in range, which
>they were happy about. The main issue, interestingly, was avoiding the
>forest of optical spurs put out by electronic-ballast fluorescent
>lights. The biggest headache was the spectral lines from the mercury
>emission, which (near the ends of the tubes) have important harmonics of
>40 kHz that extend out past a megahertz. So naturally I built them what
>was basically an AM radio, complete with a 455-kHz ceramic IF filter,
>and used an interference filter to select an optical band with no
>emission lines.
>
>The point of this story is that the low frequency bias loop used five
>diode-connected BFT25As in series, to give a wide operating range
>without adding much shot noise. It worked fine at high currents, but
>just crapped out below about 5 nA--the diodes stopped behaving like
>diodes.
>
>It turned out that the 5-GHz BFT25As were slowing down so much at those
>low currents that they ran out of gain at 1 MHz. I switched to using
>the CB junctions instead, and the circuit started working.
>
>With a sub-optimal layout, a diode-connected BFT25A can oscillate above
>about 100 uA I_C.
>
>Cheers
>
>Phil Hobbs
I did some work on Fourier Transform Mass Spectroscopy. The old
electronics had been design by a couple of chemists, and the spectrum
was dominated by junk from fluorescent lights. The 30 dB excess
wideband noise floor did make that look not as bad as it really was.
Sadly, Agilent acquired Varian and killed off both the NMR and FTMS
operations.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by Steve Wilson●June 25, 20182018-06-25
On Monday, June 25, 2018 at 8:21:23 AM UTC-4, pcdh...@gmail.com wrote:
> I didn't receive it--thanks for persisting.
> Cheers
> Phil Hobbs
Thanks for the reply. Just so you don't start worrying about other emails you may have missed, I'm pretty sure the problem is on my end. This has happened once or twice before where my email server simply refused to send emails to particular addresses. I don't know why.
Steve Wilson
Reply by ●June 25, 20182018-06-25
I didn't receive it--thanks for persisting.
Cheers
Phil Hobbs
Reply by ●June 25, 20182018-06-25
On Friday, June 22, 2018 at 2:48:45 PM UTC-4, Phil Hobbs wrote:
Here is the original readable version:
Pease Bounding and Clamping
https://drive.google.com/open?id=1mn0AMW76Y4nU63hYRv9w3xCycQm6w43X
Phil,
I sent you a copy earlier, but you didn't respond. I assume you didn't receive it or you are too busy.
There is a lot of useful information in the file that may be of interest to others, so I decided to go ahead and upload it and post the url here.
Reply by Phil Hobbs●June 24, 20182018-06-24
On 06/24/18 10:17, John Larkin wrote:
> On Sun, 24 Jun 2018 00:59:15 -0700 (PDT), pcdhobbs@gmail.com wrote:
>
>>> It's also faster (near zero t_rr), because it's never saturated.
>>
>> Falls apart at low current though, on account of beta rolling off. The 'diode-connected transistor' is the world's simplest feedback amp. I've seen them oscillate, too--that was a weird one to debug.
>>
>> Cheers
>>
>> Phil Hobbs
>
> I'll never get any sleep if you keep inventing horrors like that.
>
I did a proof of concept for a long range IR remote control for Samsung
some years back--it got them a factor of three increase in range, which
they were happy about. The main issue, interestingly, was avoiding the
forest of optical spurs put out by electronic-ballast fluorescent
lights. The biggest headache was the spectral lines from the mercury
emission, which (near the ends of the tubes) have important harmonics of
40 kHz that extend out past a megahertz. So naturally I built them what
was basically an AM radio, complete with a 455-kHz ceramic IF filter,
and used an interference filter to select an optical band with no
emission lines.
The point of this story is that the low frequency bias loop used five
diode-connected BFT25As in series, to give a wide operating range
without adding much shot noise. It worked fine at high currents, but
just crapped out below about 5 nA--the diodes stopped behaving like
diodes.
It turned out that the 5-GHz BFT25As were slowing down so much at those
low currents that they ran out of gain at 1 MHz. I switched to using
the CB junctions instead, and the circuit started working.
With a sub-optimal layout, a diode-connected BFT25A can oscillate above
about 100 uA I_C.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.nethttp://hobbs-eo.com
Reply by ●June 24, 20182018-06-24
On Friday, June 22, 2018 at 5:02:20 PM UTC+10, Piotr Wyderski wrote:
> I need a low current, low voltage and extremely low leakage diode.
> The gate junction of MMBFJ202 seems extremely well-suited for the job.
> The datasheet says its absolute maximum gate current is 50mA.
> Can I operate it reliably at 20mA for years? I mean, would there
> be any relevant degradation mechanism or is this junction an ordinary
> diode and I shouldn't worry about it?
The Siliconix PAD1 asnd JPAD10 were exactly that. They were part of range that also offered higher reverse currents at lower prices.
Calogic now seems to make them
http://calogic.net/j_diode.html
--
Bill Sloman, Sydney
Reply by John Larkin●June 24, 20182018-06-24
On Sun, 24 Jun 2018 00:59:15 -0700 (PDT), pcdhobbs@gmail.com wrote:
>>It's also faster (near zero t_rr), because it's never saturated.
>
>Falls apart at low current though, on account of beta rolling off. The 'diode-connected transistor' is the world's simplest feedback amp. I've seen them oscillate, too--that was a weird one to debug.
>
>Cheers
>
>Phil Hobbs
I'll never get any sleep if you keep inventing horrors like that.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
Reply by ●June 24, 20182018-06-24
>It's also faster (near zero t_rr), because it's never saturated.
Falls apart at low current though, on account of beta rolling off. The 'diode-connected transistor' is the world's simplest feedback amp. I've seen them oscillate, too--that was a weird one to debug.
Cheers
Phil Hobbs