S
server
Guest
http://www.potatosemi.com/potatosemiweb/index.html
G
Gerhard Hoffmann
Guest
Am 23.07.22 um 19:03 schrieb jlarkin@highlandsniptechnology.com:
Oh, the first reference to potato semi that is not from
a high end audio web site, and with ebay as distributor.
Sorry, no need for inverters that cannot drive 30% of their
own input capacitance with the delays given.
(last time I looked, a few years ago)
Gerhard
Oh, the first reference to potato semi that is not from
a high end audio web site, and with ebay as distributor.
Sorry, no need for inverters that cannot drive 30% of their
own input capacitance with the delays given.
(last time I looked, a few years ago)
Gerhard
P
Phil Hobbs
Guest
jlarkin@highlandsniptechnology.com wrote:
The datasheets all seem to be from 2010, and Octopart doesn\'t return
anything for a search on \'PO74\'. A pity. I could certainly use a
noiseless 1.25 GHz HC4046, for instance. (Many extra points for fixing
the oscillator nonlinearity, some extra points for moving the deadband
away from the servo point.)
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.net
http://hobbs-eo.com
The datasheets all seem to be from 2010, and Octopart doesn\'t return
anything for a search on \'PO74\'. A pity. I could certainly use a
noiseless 1.25 GHz HC4046, for instance. (Many extra points for fixing
the oscillator nonlinearity, some extra points for moving the deadband
away from the servo point.)
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.net
http://hobbs-eo.com
G
Gerhard Hoffmann
Guest
Am 23.07.22 um 19:28 schrieb Phil Hobbs:
It seems, the 4096 with it\'s cleaned-up deadband has died.
> Cheers
Gerhard
It seems, the 4096 with it\'s cleaned-up deadband has died.
> Cheers
Gerhard
P
Phil Hobbs
Guest
Gerhard Hoffmann wrote:
Yeah, we\'ve gone round the mulberry bush about the 4046\'s deadband
several times here in the last decade or so. It\'s no big deal as long
as you know the trick--a 1M resistor to ground, just enough to pull the
servo point a few nanoseconds to one side.
A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0
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.net
http://hobbs-eo.com
Yeah, we\'ve gone round the mulberry bush about the 4046\'s deadband
several times here in the last decade or so. It\'s no big deal as long
as you know the trick--a 1M resistor to ground, just enough to pull the
servo point a few nanoseconds to one side.
A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0
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.net
http://hobbs-eo.com
B
boB
Guest
On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Which phase detector do you prefer ?
boB
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Which phase detector do you prefer ?
boB
P
Phil Hobbs
Guest
boB wrote:
I haven\'t built an RF PLL in a few years, but at VHF and above I
normally use a diode ring mixer such as a Mini Circuits MPD-1. Next
time I want a narrowish-bandwidth loop with very accurate average phase,
I might try out JL\'s PECL d-flop trick.
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.net
http://hobbs-eo.com
I haven\'t built an RF PLL in a few years, but at VHF and above I
normally use a diode ring mixer such as a Mini Circuits MPD-1. Next
time I want a narrowish-bandwidth loop with very accurate average phase,
I might try out JL\'s PECL d-flop trick.
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.net
http://hobbs-eo.com
S
server
Guest
On Tue, 26 Jul 2022 08:51:01 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
What I needed wasn\'t frequency lock as such, but picosecond time
alignment of my clock the the OC3 optical data stream.
Imagine using an XOR or diode mixer to compare my vcxo to an incoming
square wave. Period is 7 ns, so a +-0.5 volt xor (or mixer) will have
an error slope of 0.3 volts per ns, 300 uv/ps. Tiny analog errors
anywhere make picoseconds of time error short term and long term. The
ecl d-flop has an essentially infinite detector gain, and differential
ecl is super temperature stable.
I analyzed the loop assuming that the effective gain was determined by
jitter and guessed that the detector output would go rail to rail
differential in 20 ps, once it was lowpass filtered. That was the
starting point for tweaking, but it was about right. There are a few
papers out there on infinite-gain pll\'s but they mostly confused me.
Simple phase detectors don\'t find lock if the VCO isn\'t already close
to the right frequency, so I used a switchable loop filter, wideband
to find lock then narrow for low jitter.
https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?dl=0
<pcdhSpamMeSenseless@electrooptical.net> wrote:
What I needed wasn\'t frequency lock as such, but picosecond time
alignment of my clock the the OC3 optical data stream.
Imagine using an XOR or diode mixer to compare my vcxo to an incoming
square wave. Period is 7 ns, so a +-0.5 volt xor (or mixer) will have
an error slope of 0.3 volts per ns, 300 uv/ps. Tiny analog errors
anywhere make picoseconds of time error short term and long term. The
ecl d-flop has an essentially infinite detector gain, and differential
ecl is super temperature stable.
I analyzed the loop assuming that the effective gain was determined by
jitter and guessed that the detector output would go rail to rail
differential in 20 ps, once it was lowpass filtered. That was the
starting point for tweaking, but it was about right. There are a few
papers out there on infinite-gain pll\'s but they mostly confused me.
Simple phase detectors don\'t find lock if the VCO isn\'t already close
to the right frequency, so I used a switchable loop filter, wideband
to find lock then narrow for low jitter.
https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?dl=0
P
Phil Hobbs
Guest
jlarkin@highlandsniptechnology.com wrote:
Yup, that\'s pretty compelling. AIUI the loop bandwidth has to be fairly
narrow, though, because there\'s a large-amplitude pseudorandom pulse
train coming out of the d-flop that you have to get rid of.
Yeah, and pull-in is unreliable if the loop filter isn\'t super simple.
When the loop is out of lock, the phase detector produces a beat note at
the difference frequency. The VCO frequency gets pushed slightly higher
on the positive half cycle of the ripple, and slightly lower on the
negative half cycle. The half cycle tends to reduce the frequency error
will get stretched out slightly, and hence the DC component of the beat
note will not be zero, but will gradually push the loop toward lock.
With a one-pole loop filter, i.e. a lead-lag integrator, the small
average DC will push the loop towards lock until it gets within the
closed-loop bandwidth, at which point it jumps into lock. This mechanism
is called \"pull-in\". It tends to be quadratically slow--if your initial
error is 10x the closed-loop bandwidth, it takes four times longer to
lock than if it\'s 5x. (Every acquisition transient is an individual, of
course, but the tendency is quadratic.)
If you put in additional poles to help get rid of the reference
frequency ripple, they phase shift the reference ripple, so that there
are beat-frequency regions where the pull-in voltage changes sign,
tending to push the loop further from lock. Once that starts happening,
the loop drifts towards the nearest stable null (where the pull-in
voltage passes through zero). This condition is called \"false lock\".
Thus it\'s usually helpful to add some acquisition aid. One can use a
phase-frequency detector, for instance, or (my fave) a triangle sweep
made out of the loop integrator plus a Schmitt trigger, e.g.
<https://electrooptical.net/www/sed/PLLSweeper2.asc>.
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.net
http://hobbs-eo.com
Yup, that\'s pretty compelling. AIUI the loop bandwidth has to be fairly
narrow, though, because there\'s a large-amplitude pseudorandom pulse
train coming out of the d-flop that you have to get rid of.
Yeah, and pull-in is unreliable if the loop filter isn\'t super simple.
When the loop is out of lock, the phase detector produces a beat note at
the difference frequency. The VCO frequency gets pushed slightly higher
on the positive half cycle of the ripple, and slightly lower on the
negative half cycle. The half cycle tends to reduce the frequency error
will get stretched out slightly, and hence the DC component of the beat
note will not be zero, but will gradually push the loop toward lock.
With a one-pole loop filter, i.e. a lead-lag integrator, the small
average DC will push the loop towards lock until it gets within the
closed-loop bandwidth, at which point it jumps into lock. This mechanism
is called \"pull-in\". It tends to be quadratically slow--if your initial
error is 10x the closed-loop bandwidth, it takes four times longer to
lock than if it\'s 5x. (Every acquisition transient is an individual, of
course, but the tendency is quadratic.)
If you put in additional poles to help get rid of the reference
frequency ripple, they phase shift the reference ripple, so that there
are beat-frequency regions where the pull-in voltage changes sign,
tending to push the loop further from lock. Once that starts happening,
the loop drifts towards the nearest stable null (where the pull-in
voltage passes through zero). This condition is called \"false lock\".
Thus it\'s usually helpful to add some acquisition aid. One can use a
phase-frequency detector, for instance, or (my fave) a triangle sweep
made out of the loop integrator plus a Schmitt trigger, e.g.
<https://electrooptical.net/www/sed/PLLSweeper2.asc>.
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.net
http://hobbs-eo.com
S
server
Guest
On Tue, 26 Jul 2022 10:41:02 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
That system sends Manchester data at 77 Mbits/sec. It sends a square
wave most of the time, with burst of data at about 22 KHz, a couple
hundred bits. This PLL actually uses the data edges to make lock
decisions too.
There are ambiguities so we may have to flip the 77 MHz clock phase
and try again.
The wobble-towards-lock is fun to see, but as the VCO freq is further
off, the wobble gets weaker and eventually doesn\'t work.
With 2 KHz loop bandwidth and a 77 MHz clock, ripple wasn\'t a problem.
VCXOs have their own lowpass filters inside, ahead of the varicap,
typically in the 10s of KHz, often undocumented.
All great fun. I had software looking for broken-lock indicators and
switching the clock phase and the loop filters, which was good enough,
given a perfect GPS based data stream and a good, expensive VCXO that
was pretty close to start.
We\'ve had a couple hundred in the field for about 20 years and they
have been very good. Too good. I\'m trying to convince the user that
it\'s time to replace them all, but the dumb things refuse to wear out.
<pcdhSpamMeSenseless@electrooptical.net> wrote:
That system sends Manchester data at 77 Mbits/sec. It sends a square
wave most of the time, with burst of data at about 22 KHz, a couple
hundred bits. This PLL actually uses the data edges to make lock
decisions too.
There are ambiguities so we may have to flip the 77 MHz clock phase
and try again.
The wobble-towards-lock is fun to see, but as the VCO freq is further
off, the wobble gets weaker and eventually doesn\'t work.
With 2 KHz loop bandwidth and a 77 MHz clock, ripple wasn\'t a problem.
VCXOs have their own lowpass filters inside, ahead of the varicap,
typically in the 10s of KHz, often undocumented.
All great fun. I had software looking for broken-lock indicators and
switching the clock phase and the loop filters, which was good enough,
given a perfect GPS based data stream and a good, expensive VCXO that
was pretty close to start.
We\'ve had a couple hundred in the field for about 20 years and they
have been very good. Too good. I\'m trying to convince the user that
it\'s time to replace them all, but the dumb things refuse to wear out.
P
Phil Hobbs
Guest
jlarkin@highlandsniptechnology.com wrote:
Like old HP laser printers.
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.net
http://hobbs-eo.com
Like old HP laser printers.
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.net
http://hobbs-eo.com
S
server
Guest
On Tue, 26 Jul 2022 11:16:04 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
Mine did, and the cartrige prices were absurd anyhow. I got a Brother
that\'s great. Refills are big and cheap, and it prints on both sides,
which I didn\'t expect from a cheap printer.
It just sits there quietly. The HP used to power itself up and do a
cleaning or something noisy in the middle of the night.
<pcdhSpamMeSenseless@electrooptical.net> wrote:
jlarkin@highlandsniptechnology.com wrote:
On Tue, 26 Jul 2022 10:41:02 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
jlarkin@highlandsniptechnology.com wrote:
On Tue, 26 Jul 2022 08:51:01 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
boB wrote:
On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
Gerhard Hoffmann wrote:
Am 23.07.22 um 19:28 schrieb Phil Hobbs:
jlarkin@highlandsniptechnology.com wrote:
http://www.potatosemi.com/potatosemiweb/index.html
Fun.
The datasheets all seem to be from 2010, and Octopart doesn\'t return
anything for a search on \'PO74\'. A pity. I could certainly use a
noiseless 1.25 GHz HC4046, for instance. (Many extra points for
fixing the oscillator nonlinearity, some extra points for moving the
deadband away from the servo point.)
It seems, the 4096 with it\'s cleaned-up deadband has died.
Cheers
Gerhard
Yeah, we\'ve gone round the mulberry bush about the 4046\'s deadband
several times here in the last decade or so. It\'s no big deal as long
as you know the trick--a 1M resistor to ground, just enough to pull the
servo point a few nanoseconds to one side.
A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0
Which phase detector do you prefer ?
I haven\'t built an RF PLL in a few years, but at VHF and above I
normally use a diode ring mixer such as a Mini Circuits MPD-1. Next
time I want a narrowish-bandwidth loop with very accurate average phase,
I might try out JL\'s PECL d-flop trick.
What I needed wasn\'t frequency lock as such, but picosecond time
alignment of my clock the the OC3 optical data stream.
Imagine using an XOR or diode mixer to compare my vcxo to an incoming
square wave. Period is 7 ns, so a +-0.5 volt xor (or mixer) will have
an error slope of 0.3 volts per ns, 300 uv/ps. Tiny analog errors
anywhere make picoseconds of time error short term and long term. The
ecl d-flop has an essentially infinite detector gain, and differential
ecl is super temperature stable.
Yup, that\'s pretty compelling. AIUI the loop bandwidth has to be fairly
narrow, though, because there\'s a large-amplitude pseudorandom pulse
train coming out of the d-flop that you have to get rid of.
That system sends Manchester data at 77 Mbits/sec. It sends a square
wave most of the time, with burst of data at about 22 KHz, a couple
hundred bits. This PLL actually uses the data edges to make lock
decisions too.
There are ambiguities so we may have to flip the 77 MHz clock phase
and try again.
I analyzed the loop assuming that the effective gain was determined by
jitter and guessed that the detector output would go rail to rail
differential in 20 ps, once it was lowpass filtered. That was the
starting point for tweaking, but it was about right. There are a few
papers out there on infinite-gain pll\'s but they mostly confused me.
Simple phase detectors don\'t find lock if the VCO isn\'t already close
to the right frequency, so I used a switchable loop filter, wideband
to find lock then narrow for low jitter.
https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?dl=0
Yeah, and pull-in is unreliable if the loop filter isn\'t super simple.
When the loop is out of lock, the phase detector produces a beat note at
the difference frequency. The VCO frequency gets pushed slightly higher
on the positive half cycle of the ripple, and slightly lower on the
negative half cycle. The half cycle tends to reduce the frequency error
will get stretched out slightly, and hence the DC component of the beat
note will not be zero, but will gradually push the loop toward lock.
The wobble-towards-lock is fun to see, but as the VCO freq is further
off, the wobble gets weaker and eventually doesn\'t work.
With a one-pole loop filter, i.e. a lead-lag integrator, the small
average DC will push the loop towards lock until it gets within the
closed-loop bandwidth, at which point it jumps into lock. This mechanism
is called \"pull-in\". It tends to be quadratically slow--if your initial
error is 10x the closed-loop bandwidth, it takes four times longer to
lock than if it\'s 5x. (Every acquisition transient is an individual, of
course, but the tendency is quadratic.)
If you put in additional poles to help get rid of the reference
frequency ripple, they phase shift the reference ripple, so that there
are beat-frequency regions where the pull-in voltage changes sign,
tending to push the loop further from lock. Once that starts happening,
the loop drifts towards the nearest stable null (where the pull-in
voltage passes through zero). This condition is called \"false lock\".
With 2 KHz loop bandwidth and a 77 MHz clock, ripple wasn\'t a problem.
VCXOs have their own lowpass filters inside, ahead of the varicap,
typically in the 10s of KHz, often undocumented.
Thus it\'s usually helpful to add some acquisition aid. One can use a
phase-frequency detector, for instance, or (my fave) a triangle sweep
made out of the loop integrator plus a Schmitt trigger, e.g.
https://electrooptical.net/www/sed/PLLSweeper2.asc>.
All great fun. I had software looking for broken-lock indicators and
switching the clock phase and the loop filters, which was good enough,
given a perfect GPS based data stream and a good, expensive VCXO that
was pretty close to start.
We\'ve had a couple hundred in the field for about 20 years and they
have been very good. Too good. I\'m trying to convince the user that
it\'s time to replace them all, but the dumb things refuse to wear out.
Like old HP laser printers.
Cheers
Phil Hobbs
Mine did, and the cartrige prices were absurd anyhow. I got a Brother
that\'s great. Refills are big and cheap, and it prints on both sides,
which I didn\'t expect from a cheap printer.
It just sits there quietly. The HP used to power itself up and do a
cleaning or something noisy in the middle of the night.
P
Phil Hobbs
Guest
jlarkin@highlandsniptechnology.com wrote:
We have a LaserJet 2300DTN, which does duplex as well. It\'s recently
become a bit hard to get good cartridges for it, so it may have to be
replaced.
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.net
http://hobbs-eo.com
On Tue, 26 Jul 2022 11:16:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
jlarkin@highlandsniptechnology.com wrote:
On Tue, 26 Jul 2022 10:41:02 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
jlarkin@highlandsniptechnology.com wrote:
On Tue, 26 Jul 2022 08:51:01 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
boB wrote:
On Sat, 23 Jul 2022 14:55:03 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
Gerhard Hoffmann wrote:
Am 23.07.22 um 19:28 schrieb Phil Hobbs:
jlarkin@highlandsniptechnology.com wrote:
http://www.potatosemi.com/potatosemiweb/index.html
Fun.
The datasheets all seem to be from 2010, and Octopart doesn\'t return
anything for a search on \'PO74\'. A pity. I could certainly use a
noiseless 1.25 GHz HC4046, for instance. (Many extra points for
fixing the oscillator nonlinearity, some extra points for moving the
deadband away from the servo point.)
It seems, the 4096 with it\'s cleaned-up deadband has died.
Cheers
Gerhard
Yeah, we\'ve gone round the mulberry bush about the 4046\'s deadband
several times here in the last decade or so. It\'s no big deal as long
as you know the trick--a 1M resistor to ground, just enough to pull the
servo point a few nanoseconds to one side.
A 1.25 GHz version would be pretty slick, in a 1980s retro sort of way. ;0
Which phase detector do you prefer ?
I haven\'t built an RF PLL in a few years, but at VHF and above I
normally use a diode ring mixer such as a Mini Circuits MPD-1. Next
time I want a narrowish-bandwidth loop with very accurate average phase,
I might try out JL\'s PECL d-flop trick.
What I needed wasn\'t frequency lock as such, but picosecond time
alignment of my clock the the OC3 optical data stream.
Imagine using an XOR or diode mixer to compare my vcxo to an incoming
square wave. Period is 7 ns, so a +-0.5 volt xor (or mixer) will have
an error slope of 0.3 volts per ns, 300 uv/ps. Tiny analog errors
anywhere make picoseconds of time error short term and long term. The
ecl d-flop has an essentially infinite detector gain, and differential
ecl is super temperature stable.
Yup, that\'s pretty compelling. AIUI the loop bandwidth has to be fairly
narrow, though, because there\'s a large-amplitude pseudorandom pulse
train coming out of the d-flop that you have to get rid of.
That system sends Manchester data at 77 Mbits/sec. It sends a square
wave most of the time, with burst of data at about 22 KHz, a couple
hundred bits. This PLL actually uses the data edges to make lock
decisions too.
There are ambiguities so we may have to flip the 77 MHz clock phase
and try again.
I analyzed the loop assuming that the effective gain was determined by
jitter and guessed that the detector output would go rail to rail
differential in 20 ps, once it was lowpass filtered. That was the
starting point for tweaking, but it was about right. There are a few
papers out there on infinite-gain pll\'s but they mostly confused me.
Simple phase detectors don\'t find lock if the VCO isn\'t already close
to the right frequency, so I used a switchable loop filter, wideband
to find lock then narrow for low jitter.
https://www.dropbox.com/s/cobd3t4eorcsgrt/22S880D.pdf?dl=0
Yeah, and pull-in is unreliable if the loop filter isn\'t super simple.
When the loop is out of lock, the phase detector produces a beat note at
the difference frequency. The VCO frequency gets pushed slightly higher
on the positive half cycle of the ripple, and slightly lower on the
negative half cycle. The half cycle tends to reduce the frequency error
will get stretched out slightly, and hence the DC component of the beat
note will not be zero, but will gradually push the loop toward lock.
The wobble-towards-lock is fun to see, but as the VCO freq is further
off, the wobble gets weaker and eventually doesn\'t work.
With a one-pole loop filter, i.e. a lead-lag integrator, the small
average DC will push the loop towards lock until it gets within the
closed-loop bandwidth, at which point it jumps into lock. This mechanism
is called \"pull-in\". It tends to be quadratically slow--if your initial
error is 10x the closed-loop bandwidth, it takes four times longer to
lock than if it\'s 5x. (Every acquisition transient is an individual, of
course, but the tendency is quadratic.)
If you put in additional poles to help get rid of the reference
frequency ripple, they phase shift the reference ripple, so that there
are beat-frequency regions where the pull-in voltage changes sign,
tending to push the loop further from lock. Once that starts happening,
the loop drifts towards the nearest stable null (where the pull-in
voltage passes through zero). This condition is called \"false lock\".
With 2 KHz loop bandwidth and a 77 MHz clock, ripple wasn\'t a problem.
VCXOs have their own lowpass filters inside, ahead of the varicap,
typically in the 10s of KHz, often undocumented.
Thus it\'s usually helpful to add some acquisition aid. One can use a
phase-frequency detector, for instance, or (my fave) a triangle sweep
made out of the loop integrator plus a Schmitt trigger, e.g.
https://electrooptical.net/www/sed/PLLSweeper2.asc>.
All great fun. I had software looking for broken-lock indicators and
switching the clock phase and the loop filters, which was good enough,
given a perfect GPS based data stream and a good, expensive VCXO that
was pretty close to start.
We\'ve had a couple hundred in the field for about 20 years and they
have been very good. Too good. I\'m trying to convince the user that
it\'s time to replace them all, but the dumb things refuse to wear out.
Like old HP laser printers.
Cheers
Phil Hobbs
Mine did, and the cartrige prices were absurd anyhow. I got a Brother
that\'s great. Refills are big and cheap, and it prints on both sides,
which I didn\'t expect from a cheap printer.
It just sits there quietly. The HP used to power itself up and do a
cleaning or something noisy in the middle of the night.
We have a LaserJet 2300DTN, which does duplex as well. It\'s recently
become a bit hard to get good cartridges for it, so it may have to be
replaced.
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.net
http://hobbs-eo.com
C
Clifford Heath
Guest
On 27/7/22 04:20, Phil Hobbs wrote:
My venerable HP LJ6L only died a couple of years back, after well over a
decade of service, including many toner transfer PCBs. When I dismantled
it I found no fewer than eight things broken internally, yet none had
stopped it from working until the last one.
The replacement HP P2055dn is nice with the duplexer and all, but it has
such advanced toner management (turning solid blacks into microscopic
cross-hatch patterns) that it\'s useless for toner transfer, so it\'s just
as well the PCB prototyping services are so cheap and quick these days.
I still miss being able to do a Saturday afternoon turn-around from
layout to soldering an under an hour though.
Clifford Heath
jlarkin@highlandsniptechnology.com wrote:
On Tue, 26 Jul 2022 11:16:04 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
Like old HP laser printers.
Mine did, and the cartrige prices were absurd anyhow. I got a Brother
that\'s great. Refills are big and cheap, and it prints on both sides,
which I didn\'t expect from a cheap printer.
It just sits there quietly. The HP used to power itself up and do a
cleaning or something noisy in the middle of the night.
We have a LaserJet 2300DTN, which does duplex as well. It\'s recently
become a bit hard to get good cartridges for it, so it may have to be
replaced.
My venerable HP LJ6L only died a couple of years back, after well over a
decade of service, including many toner transfer PCBs. When I dismantled
it I found no fewer than eight things broken internally, yet none had
stopped it from working until the last one.
The replacement HP P2055dn is nice with the duplexer and all, but it has
such advanced toner management (turning solid blacks into microscopic
cross-hatch patterns) that it\'s useless for toner transfer, so it\'s just
as well the PCB prototyping services are so cheap and quick these days.
I still miss being able to do a Saturday afternoon turn-around from
layout to soldering an under an hour though.
Clifford Heath
R
Rich S
Guest
HI Clifford, Re cross hatch pattern, maybe it is in \"toner-saving\"
mode, a.k.a. draft mode. If even \"standard\" quality has this problem
then try \"high-quality\" mode. (I couldn\'t confirm that this model has
those quality settings, as strangely, HP does not have any specs
for it posted on their Support area.)
In general monochrome lasers from HP & Brother have had the fewest
reported major problems (\'more reliable\') than any other brand or type
of printer. If queried about what printer to buy, always start your
recommendations there, friends.
Regards, Rich S.
C
Clifford Heath
Guest
On 27/7/22 11:58, Rich S wrote:
I think I\'ve tried all the settings hat are available to me through
MacOS CUPS printer subsystem, and through the printer menus. It\'s
possible I missed something of course. But \"solid\" blacks were always
difficult for laser mechanisms, because to evenly distribute a strong
static charge (without it repelling itself and causing white blotches)
is hard. So I think the cross-hatching is a feature of how they handle that.
I also acquired a HP Color C1518ni (best possible price - I swapped it
for a homegrown pumpkin!), but only turn it on when I want colour,
because the cartridges are so expensive.
A lot of folk who\'ve tried toner transfer with Brother lasers say that
the toner doesn\'t transfer. I don\'t know what series or version those
were, but I didn\'t want to buy one to find out that it didn\'t work.
Clifford Heath.
I think I\'ve tried all the settings hat are available to me through
MacOS CUPS printer subsystem, and through the printer menus. It\'s
possible I missed something of course. But \"solid\" blacks were always
difficult for laser mechanisms, because to evenly distribute a strong
static charge (without it repelling itself and causing white blotches)
is hard. So I think the cross-hatching is a feature of how they handle that.
I also acquired a HP Color C1518ni (best possible price - I swapped it
for a homegrown pumpkin!), but only turn it on when I want colour,
because the cartridges are so expensive.
A lot of folk who\'ve tried toner transfer with Brother lasers say that
the toner doesn\'t transfer. I don\'t know what series or version those
were, but I didn\'t want to buy one to find out that it didn\'t work.
Clifford Heath.
D
Dan Purgert
Guest
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Clifford Heath wrote:
I have a Brother 21x0 (70? 80? can\'t remember, it\'s still buried under
moving boxes). It works alright; but in doing research I have found
that those models (~2004-6) were the start of the \"newer(tm)\" toners
that fuse at higher temperatures; which lead to problems for various
toner-transfer methods (I\'ve only done the laminator approach).
Granted, I also don\'t do toner-transfer all that much, so the errors
could just as easily be my fault as the toner\'s.
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|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860
Hash: SHA512
Clifford Heath wrote:
I have a Brother 21x0 (70? 80? can\'t remember, it\'s still buried under
moving boxes). It works alright; but in doing research I have found
that those models (~2004-6) were the start of the \"newer(tm)\" toners
that fuse at higher temperatures; which lead to problems for various
toner-transfer methods (I\'ve only done the laminator approach).
Granted, I also don\'t do toner-transfer all that much, so the errors
could just as easily be my fault as the toner\'s.
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--
|_|O|_|
|_|_|O| Github: https://github.com/dpurgert
|O|O|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860