Of course the galena was just for fun, and never actually did very much.
The seleniums and tubes were salvaged from old TVs when I was a boy.
(It was a good thing for me that frying seleniums smell so horrible--I
didn\'t realize that the fumes were dangerous.)
There are still things that tubes are unbeatable at. My last tube
circuit used an 811A to control a grid in an electrostatic drift
chamber--it needed to switch some hundreds of volts, and then go
completely away, i.e. have very low leakage and capacitance when off.
(Of course, that was in about 1990.)
My tube-type GDOs are some of my favorite instruments.
(I once needed some vibrators to help parts in tubes slide down
low-slope feeders on a pick-and-place line, for a friend who had an
assembly shop. I found a suitable gadget at Good Vibrations, a
ladies\', umm, accessory store. That was fun.)
Of course the galena was just for fun, and never actually did very much.
The seleniums and tubes were salvaged from old TVs when I was a boy.
(It was a good thing for me that frying seleniums smell so horrible--I
didn\'t realize that the fumes were dangerous.)
There are still things that tubes are unbeatable at. My last tube
circuit used an 811A to control a grid in an electrostatic drift
chamber--it needed to switch some hundreds of volts, and then go
completely away, i.e. have very low leakage and capacitance when off.
(Of course, that was in about 1990.)
My tube-type GDOs are some of my favorite instruments.
Some of the Keithley electrometers used a special electrometer tube.
Mine uses an early vintage mosfet.
John, I do remember my 1st pickle-jar AM radio with Xtal earbud and
On 2023-05-04 12:26, John Larkin wrote:
On Thu, 4 May 2023 10:26:55 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-05-04 08:39, John Larkin wrote:
On Thu, 4 May 2023 00:32:10 -0400, chuck <donnyduck@gmail.com> wrote:
On 02/05/2023 5:53 p.m., John Larkin wrote:
On Tue, 2 May 2023 16:23:53 -0400, chuck <donnyduck@gmail.com> wrote:
On 02/05/2023 2:43 p.m., John Larkin wrote:
The CR things are crystal rectifiers.
Not quite.
CR = CURRENT RECTIFIER
This design intent was to control startup sequence to ensure the highest
voltage source enables the 50V which enables the 15V.
If the HV was slow in rising, some circuit that uses both supply
voltages would see that as a polarity reversal.
For 3 terminal LDO\'s they mitigate this prompting users to add a reverse
diode from input to output so if the higher input voltage goes down
fast, the diode will protect BE junctions from excessive reverse voltage
|Vr| > 5V.
It was a good question that did not deserve snarky responses.
Tony Stewart
EE since 1975
No snark at all. Crystal Rectifier was the initial meaning of CR.
https://www.reddit.com/r/diyelectronics/comments/yl5s28/whats_this_strange_component_designator_cr1/
https://en.wikipedia.org/wiki/Crystal_detector
https://en.wikipedia.org/wiki/Diode
Rad Lab vol 15 is titled \"Crystal Rectifiers.\" Point-contact diode
mixers were one of the three keys to microwave radar, and radar won
WWII.
The diodes in the Tek schematic are not current regulator diodes,
which are actually a form of jfet. I doubt they existed then. I have
not previously heard the term CURRENT RECTIFIER.
John Larkin
EE since 1966
John I guess I started design in Aerospace at the right time in 1975.
and it was probably my draftsman who said it stood for CURRENT RECTIFIER
which a common descriptor. Although I read most of the Mil-Specs and STD
HBBK\'s from our vast library at Bristol Aerospace, I can\'t recall seeing
it there. It was nice to have any test equipment you needed.
Here is the TEK7904 mainframe service manual.
https://w140.com/Tek_7904_OCRed_by_Tabalabs.pdf
I guess you youngsters don\'t remember point-contact rectifiers,
selenium rectifiers, vacuum tube rectifiers, copper oxide rectifiers,
tungar rectifiers, mercury rectifiers, ignitron rectifiers, vibrator
rectifiers, synchronous rectifiers, foxhole (rusty razor blade)
rectifiers, galena rectifiers, or electrolytic rectifiers.
I actually saw a tungar rectifier in operation when I was a kid. In a
gas station.
There were germanium, silicon, and gallium arsenide rectifiers in
WWII. I *don\'t* remember WWII.
I\'m a skosh younger than you, but I\'ve built things with selenium, tube,
point contact, synchronous, and galena rectifiers. I have a couple of
dozen point contact diodes in a Lista cabinet bin (1N34A, 1N38B, and
1N21C).
Your synchronous rectifiers were probably mosfets, but I was thinking
of the motor-driven mechanical contact types.
(Somebody built a DRAM with leaded capacitors on a spinning disk.)
I think that was John D. Atanasoff (of Atanasoff-Berry Computer fame).
One cool device was a DPDT vibrator, sometimes used in car radios. One
set of contacts pushed 12 volts into a transformer primary and the
other set rectified the secondary. Old tube car radios had some
interesting technology. I used to get them free from junkyards.
Yup. As a teenager, I had an old T19 Mk III tank transceiver that
(iirc) had a companion vibrator supply. Interesting gizmo--I never did
get it to work. I remember a weird E1148 VHF superregen oscillator tube
with two caps on it.
(I once needed some vibrators to help parts in tubes slide down
low-slope feeders on a pick-and-place line, for a friend who had an
assembly shop. I found a suitable gadget at Good Vibrations, a
ladies\', umm, accessory store. That was fun.)
Of course the galena was just for fun, and never actually did very much.
The seleniums and tubes were salvaged from old TVs when I was a boy.
(It was a good thing for me that frying seleniums smell so horrible--I
didn\'t realize that the fumes were dangerous.)
There are still things that tubes are unbeatable at. My last tube
circuit used an 811A to control a grid in an electrostatic drift
chamber--it needed to switch some hundreds of volts, and then go
completely away, i.e. have very low leakage and capacitance when off.
(Of course, that was in about 1990.)
My tube-type GDOs are some of my favorite instruments.
Some of the Keithley electrometers used a special electrometer tube.
Mine uses an early vintage mosfet.
I have one of each: a 405 and a 610C like yours. The 405 works on the
100-fA scale if you let it warm up for an hour or so.
https://www.dropbox.com/s/lo8xsx2x07b4zy4/Welwyn_1G_Keithley.jpg?raw=1
When I first played with mosfets I built a voltage follower and
accidentally left the gate open. The source voltage froze and didn\'t
change a bit. I was amazed. Now one can do cool things with a 2N7000.
If you can find one that isn\'t gate-protected, these days. I have a
reel of 2N7002E\'s because NXP discontinued them.
Cheers
Phil Hobbs
On Thu, 4 May 2023 12:57:03 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-05-04 12:26, John Larkin wrote:
On Thu, 4 May 2023 10:26:55 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-05-04 08:39, John Larkin wrote:
On Thu, 4 May 2023 00:32:10 -0400, chuck <donnyduck@gmail.com> wrote:
On 02/05/2023 5:53 p.m., John Larkin wrote:
On Tue, 2 May 2023 16:23:53 -0400, chuck <donnyduck@gmail.com> wrote:
On 02/05/2023 2:43 p.m., John Larkin wrote:
The CR things are crystal rectifiers.
Not quite.
CR = CURRENT RECTIFIER
This design intent was to control startup sequence to ensure the highest
voltage source enables the 50V which enables the 15V.
If the HV was slow in rising, some circuit that uses both supply
voltages would see that as a polarity reversal.
For 3 terminal LDO\'s they mitigate this prompting users to add a reverse
diode from input to output so if the higher input voltage goes down
fast, the diode will protect BE junctions from excessive reverse voltage
|Vr| > 5V.
It was a good question that did not deserve snarky responses.
Tony Stewart
EE since 1975
No snark at all. Crystal Rectifier was the initial meaning of CR.
https://www.reddit.com/r/diyelectronics/comments/yl5s28/whats_this_strange_component_designator_cr1/
https://en.wikipedia.org/wiki/Crystal_detector
https://en.wikipedia.org/wiki/Diode
Rad Lab vol 15 is titled \"Crystal Rectifiers.\" Point-contact diode
mixers were one of the three keys to microwave radar, and radar won
WWII.
The diodes in the Tek schematic are not current regulator diodes,
which are actually a form of jfet. I doubt they existed then. I have
not previously heard the term CURRENT RECTIFIER.
John Larkin
EE since 1966
John I guess I started design in Aerospace at the right time in 1975.
and it was probably my draftsman who said it stood for CURRENT RECTIFIER
which a common descriptor. Although I read most of the Mil-Specs and STD
HBBK\'s from our vast library at Bristol Aerospace, I can\'t recall seeing
it there. It was nice to have any test equipment you needed.
Here is the TEK7904 mainframe service manual.
https://w140.com/Tek_7904_OCRed_by_Tabalabs.pdf
I guess you youngsters don\'t remember point-contact rectifiers,
selenium rectifiers, vacuum tube rectifiers, copper oxide rectifiers,
tungar rectifiers, mercury rectifiers, ignitron rectifiers, vibrator
rectifiers, synchronous rectifiers, foxhole (rusty razor blade)
rectifiers, galena rectifiers, or electrolytic rectifiers.
I actually saw a tungar rectifier in operation when I was a kid. In a
gas station.
There were germanium, silicon, and gallium arsenide rectifiers in
WWII. I *don\'t* remember WWII.
I\'m a skosh younger than you, but I\'ve built things with selenium, tube,
point contact, synchronous, and galena rectifiers. I have a couple of
dozen point contact diodes in a Lista cabinet bin (1N34A, 1N38B, and
1N21C).
Your synchronous rectifiers were probably mosfets, but I was thinking
of the motor-driven mechanical contact types.
(Somebody built a DRAM with leaded capacitors on a spinning disk.)
I think that was John D. Atanasoff (of Atanasoff-Berry Computer fame).
One cool device was a DPDT vibrator, sometimes used in car radios. One
set of contacts pushed 12 volts into a transformer primary and the
other set rectified the secondary. Old tube car radios had some
interesting technology. I used to get them free from junkyards.
Yup. As a teenager, I had an old T19 Mk III tank transceiver that
(iirc) had a companion vibrator supply. Interesting gizmo--I never did
get it to work. I remember a weird E1148 VHF superregen oscillator tube
with two caps on it.
(I once needed some vibrators to help parts in tubes slide down
low-slope feeders on a pick-and-place line, for a friend who had an
assembly shop. I found a suitable gadget at Good Vibrations, a
ladies\', umm, accessory store. That was fun.)
Of course the galena was just for fun, and never actually did very much.
The seleniums and tubes were salvaged from old TVs when I was a boy.
(It was a good thing for me that frying seleniums smell so horrible--I
didn\'t realize that the fumes were dangerous.)
There are still things that tubes are unbeatable at. My last tube
circuit used an 811A to control a grid in an electrostatic drift
chamber--it needed to switch some hundreds of volts, and then go
completely away, i.e. have very low leakage and capacitance when off.
(Of course, that was in about 1990.)
My tube-type GDOs are some of my favorite instruments.
Some of the Keithley electrometers used a special electrometer tube.
Mine uses an early vintage mosfet.
I have one of each: a 405 and a 610C like yours. The 405 works on the
100-fA scale if you let it warm up for an hour or so.
https://www.dropbox.com/s/lo8xsx2x07b4zy4/Welwyn_1G_Keithley.jpg?raw=1
When I first played with mosfets I built a voltage follower and
accidentally left the gate open. The source voltage froze and didn\'t
change a bit. I was amazed. Now one can do cool things with a 2N7000.
If you can find one that isn\'t gate-protected, these days. I have a
reel of 2N7002E\'s because NXP discontinued them.
My 610 doesn\'t work in fast mode, just goes bonkers. Sometimes a
measurement takes half an hour to settle and I have to walk around my
office holding a ground wire. Does yours work in fast mode?
On 2023-05-04 20:22, John Larkin wrote:
On Thu, 4 May 2023 12:57:03 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-05-04 12:26, John Larkin wrote:
On Thu, 4 May 2023 10:26:55 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2023-05-04 08:39, John Larkin wrote:
On Thu, 4 May 2023 00:32:10 -0400, chuck <donnyduck@gmail.com> wrote:
On 02/05/2023 5:53 p.m., John Larkin wrote:
On Tue, 2 May 2023 16:23:53 -0400, chuck <donnyduck@gmail.com> wrote:
On 02/05/2023 2:43 p.m., John Larkin wrote:
The CR things are crystal rectifiers.
Not quite.
CR = CURRENT RECTIFIER
This design intent was to control startup sequence to ensure the highest
voltage source enables the 50V which enables the 15V.
If the HV was slow in rising, some circuit that uses both supply
voltages would see that as a polarity reversal.
For 3 terminal LDO\'s they mitigate this prompting users to add a reverse
diode from input to output so if the higher input voltage goes down
fast, the diode will protect BE junctions from excessive reverse voltage
|Vr| > 5V.
It was a good question that did not deserve snarky responses.
Tony Stewart
EE since 1975
No snark at all. Crystal Rectifier was the initial meaning of CR.
https://www.reddit.com/r/diyelectronics/comments/yl5s28/whats_this_strange_component_designator_cr1/
https://en.wikipedia.org/wiki/Crystal_detector
https://en.wikipedia.org/wiki/Diode
Rad Lab vol 15 is titled \"Crystal Rectifiers.\" Point-contact diode
mixers were one of the three keys to microwave radar, and radar won
WWII.
The diodes in the Tek schematic are not current regulator diodes,
which are actually a form of jfet. I doubt they existed then. I have
not previously heard the term CURRENT RECTIFIER.
John Larkin
EE since 1966
John I guess I started design in Aerospace at the right time in 1975.
and it was probably my draftsman who said it stood for CURRENT RECTIFIER
which a common descriptor. Although I read most of the Mil-Specs and STD
HBBK\'s from our vast library at Bristol Aerospace, I can\'t recall seeing
it there. It was nice to have any test equipment you needed.
Here is the TEK7904 mainframe service manual.
https://w140.com/Tek_7904_OCRed_by_Tabalabs.pdf
I guess you youngsters don\'t remember point-contact rectifiers,
selenium rectifiers, vacuum tube rectifiers, copper oxide rectifiers,
tungar rectifiers, mercury rectifiers, ignitron rectifiers, vibrator
rectifiers, synchronous rectifiers, foxhole (rusty razor blade)
rectifiers, galena rectifiers, or electrolytic rectifiers.
I actually saw a tungar rectifier in operation when I was a kid. In a
gas station.
There were germanium, silicon, and gallium arsenide rectifiers in
WWII. I *don\'t* remember WWII.
I\'m a skosh younger than you, but I\'ve built things with selenium, tube,
point contact, synchronous, and galena rectifiers. I have a couple of
dozen point contact diodes in a Lista cabinet bin (1N34A, 1N38B, and
1N21C).
Your synchronous rectifiers were probably mosfets, but I was thinking
of the motor-driven mechanical contact types.
(Somebody built a DRAM with leaded capacitors on a spinning disk.)
I think that was John D. Atanasoff (of Atanasoff-Berry Computer fame).
One cool device was a DPDT vibrator, sometimes used in car radios. One
set of contacts pushed 12 volts into a transformer primary and the
other set rectified the secondary. Old tube car radios had some
interesting technology. I used to get them free from junkyards.
Yup. As a teenager, I had an old T19 Mk III tank transceiver that
(iirc) had a companion vibrator supply. Interesting gizmo--I never did
get it to work. I remember a weird E1148 VHF superregen oscillator tube
with two caps on it.
(I once needed some vibrators to help parts in tubes slide down
low-slope feeders on a pick-and-place line, for a friend who had an
assembly shop. I found a suitable gadget at Good Vibrations, a
ladies\', umm, accessory store. That was fun.)
Of course the galena was just for fun, and never actually did very much.
The seleniums and tubes were salvaged from old TVs when I was a boy.
(It was a good thing for me that frying seleniums smell so horrible--I
didn\'t realize that the fumes were dangerous.)
There are still things that tubes are unbeatable at. My last tube
circuit used an 811A to control a grid in an electrostatic drift
chamber--it needed to switch some hundreds of volts, and then go
completely away, i.e. have very low leakage and capacitance when off.
(Of course, that was in about 1990.)
My tube-type GDOs are some of my favorite instruments.
Some of the Keithley electrometers used a special electrometer tube.
Mine uses an early vintage mosfet.
I have one of each: a 405 and a 610C like yours. The 405 works on the
100-fA scale if you let it warm up for an hour or so.
https://www.dropbox.com/s/lo8xsx2x07b4zy4/Welwyn_1G_Keithley.jpg?raw=1
When I first played with mosfets I built a voltage follower and
accidentally left the gate open. The source voltage froze and didn\'t
change a bit. I was amazed. Now one can do cool things with a 2N7000.
If you can find one that isn\'t gate-protected, these days. I have a
reel of 2N7002E\'s because NXP discontinued them.
My 610 doesn\'t work in fast mode, just goes bonkers. Sometimes a
measurement takes half an hour to settle and I have to walk around my
office holding a ground wire. Does yours work in fast mode?
Generally, but not on the three bottom ranges (10, 30, and 100 fA FS).
The 10 fA scale is apparently just there to decorate the front
panel--it\'s too unstable to be useful even in slow mode.
Possibly hooking up a LabJack to the analog output and averaging awhile
might fix it, but if I needed to do that I\'d certainly wire up something
dead bug style in a cast-aluminum stomp box instead of using the Keithley.
Sometime in my declining years I might retrofit my old 602, which is
sort of like a more primitive 610C that runs off a zillion dry cells.
I\'d probably pick a 100-pf polystyrene cap out of my drawer, wire it up
as a current integrator with something like an LMC6001 op amp, and
connect it straight to the input. with some very low leakage reset switch.
Then I\'d do a F/V for higher currents, and differentiate the ramp for
lower ones.
Cheers
Phil Hobbs