K
Klaus Kragelund
Guest
On Tuesday, January 7, 2020 at 7:37:13 AM UTC+1, Steve Wilson wrote:
Very nice indeed. Thanks
Very nice indeed. Thanks
Guest
On Tue, 7 Jan 2020 06:37:09 -0000 (UTC), Steve Wilson <no@spam.com>
wrote:
Find one that works and keep buying them. If volume is high, have an
understanding with the maker to not change the fab. Smearing out a
spectrum is hardly a precise thing anyhow.
As far as his circuit goes, we don't know what it is.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
wrote:
Find one that works and keep buying them. If volume is high, have an
understanding with the maker to not change the fab. Smearing out a
spectrum is hardly a precise thing anyhow.
As far as his circuit goes, we don't know what it is.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
Guest
On Tue, 7 Jan 2020 01:25:38 -0800 (PST), Klaus Kragelund
<klauskvik@hotmail.com> wrote:
That was just a tangent discussion about generating true randomness.
All you need is a triangle wave to modulate the frequency. Best-case,
all you might need is a uP pin and one resistor.
Or maybe just the uP pin.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
<klauskvik@hotmail.com> wrote:
That was just a tangent discussion about generating true randomness.
All you need is a triangle wave to modulate the frequency. Best-case,
all you might need is a uP pin and one resistor.
Or maybe just the uP pin.
--
John Larkin Highland Technology, Inc
lunatic fringe electronics
S
Steve Wilson
Guest
jlarkin@highlandsniptechnology.com wrote:
It may be hard to find a diode with high enough capacity to work in his
circuit. Shielding and proper oscillator adjustment may be all that is
needed.
> As far as his circuit goes, we don't know what it is.
Klaus seems to like Colpitts, Clapp and Pierce. How many other types are
there?
It may be hard to find a diode with high enough capacity to work in his
circuit. Shielding and proper oscillator adjustment may be all that is
needed.
> As far as his circuit goes, we don't know what it is.
Klaus seems to like Colpitts, Clapp and Pierce. How many other types are
there?
R
Robert Baer
Guest
Klaus Kragelund wrote:
Do not believe a word of that bunk.
Many power diodes will act a a varicap, and even in the FM band.
Diodes are not cheap?
Do not believe a word of that bunk.
Many power diodes will act a a varicap, and even in the FM band.
S
Steve Wilson
Guest
Steve Wilson <no@spam.com> wrote:
It occurs to me it may be a simple layout problem. Perhaps Klaus is using
two-sided FR1 or FR2 with not much room for a good ground plane. There might
be room for improvement.
It occurs to me it may be a simple layout problem. Perhaps Klaus is using
two-sided FR1 or FR2 with not much room for a good ground plane. There might
be room for improvement.
C
Clifford Heath
Guest
On 8/1/20 7:06 am, Robert Baer wrote:
It's not the power, but the voltage. High stand-off voltages are
achieved with a PIN structure, and that gives you the varactor behaviour.
It's not the power, but the voltage. High stand-off voltages are
achieved with a PIN structure, and that gives you the varactor behaviour.
K
Klaus Kragelund
Guest
On Tuesday, January 7, 2020 at 5:04:57 PM UTC+1, jla...@highlandsniptechnology.com wrote:
The Colpitts BJT base is biased with 6k and 2k from a 5V supply (AFAIC). So to move the midpoint to have a different trigger point, I need to inject a current into the midpoint
It seems to me, this will mostly just offset the bias point and not alter the frequency much. I did a simulation of it, where I injected a 100Hz sine of 10V into the bias point with a 1nF cap. That did move the frequency somewhat, but did not seem to be consistent (the 10V 100Hz was from the ac ripple on the DC link capacitor, since that is a place I can get a rampling voltage without the aid of the microcontroller. Must try the micro instead, since the DC link voltage ripple is load dependant
A lot of weak words, I have not had much time to look into it, have a manager that wants me to work on other stuff
Cheers
Klaus
The Colpitts BJT base is biased with 6k and 2k from a 5V supply (AFAIC). So to move the midpoint to have a different trigger point, I need to inject a current into the midpoint
It seems to me, this will mostly just offset the bias point and not alter the frequency much. I did a simulation of it, where I injected a 100Hz sine of 10V into the bias point with a 1nF cap. That did move the frequency somewhat, but did not seem to be consistent (the 10V 100Hz was from the ac ripple on the DC link capacitor, since that is a place I can get a rampling voltage without the aid of the microcontroller. Must try the micro instead, since the DC link voltage ripple is load dependant
A lot of weak words, I have not had much time to look into it, have a manager that wants me to work on other stuff
Cheers
Klaus
K
Klaus Kragelund
Guest
On Tuesday, January 7, 2020 at 6:36:00 PM UTC+1, Steve Wilson wrote:
I like the Colpitts due to a single inductor circuit, whereas the Hartley needs two inductors
This link has some details of the workings and formulas:
http://www.eng.auburn.edu/~deanron/Lecture_21419.pdf
Cheers
Klaus
I like the Colpitts due to a single inductor circuit, whereas the Hartley needs two inductors
This link has some details of the workings and formulas:
http://www.eng.auburn.edu/~deanron/Lecture_21419.pdf
Cheers
Klaus
K
Klaus Kragelund
Guest
On Tuesday, January 7, 2020 at 10:20:11 PM UTC+1, Steve Wilson wrote:
We have 4 sided board. This is not a layout problem, but we have a parasitic capacitance over an barrier with a cable connected. THe oscillator is no symmetric, so it forces a current into this parasitic capacitor which spreads into the cable
I could filter it out, but that is expensive. I could make the oscillator symmetric around GND, but that is not easy for this design
Cheers
Klaus
We have 4 sided board. This is not a layout problem, but we have a parasitic capacitance over an barrier with a cable connected. THe oscillator is no symmetric, so it forces a current into this parasitic capacitor which spreads into the cable
I could filter it out, but that is expensive. I could make the oscillator symmetric around GND, but that is not easy for this design
Cheers
Klaus
P
Phil Hobbs
Guest
On 2020-01-07 19:05, Klaus Kragelund wrote:
The key distinctive of the Hartley is that the inductors are coupled, so
that you get better impedance transformation from the emitter to the
base. A single-layer tapped coil will give coupling coefficients of
about 0.4 to 0.7, depending on the geometry.
With uncoupled inductors, it becomes just a minor Colpitts variant.
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 key distinctive of the Hartley is that the inductors are coupled, so
that you get better impedance transformation from the emitter to the
base. A single-layer tapped coil will give coupling coefficients of
about 0.4 to 0.7, depending on the geometry.
With uncoupled inductors, it becomes just a minor Colpitts variant.
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
J
Jeroen Belleman
Guest
Phil Hobbs wrote:
Funny how different people select different criteria to
classify oscillators. To me, the distinction between Colpitts
and Hartley is that the former has two capacitive reactances
and one inductive one as principal components of its tank,
while the latter has L's where the former had C's and vice-
versa. In my mind, the fact that the Hartley inductors might
be coupled is just a minor variant.
Those criteria are vague, anyway. A capacitor in series with
the Colpitts inductor and it turns into a Clapp. Choose the
node between the two capacitors of a Colpitts for GND and
suddenly it gets called a Pierce. What if I do both?
There so many ways to make oscillators and only a few
names to choose from.
Jeroen Belleman
Funny how different people select different criteria to
classify oscillators. To me, the distinction between Colpitts
and Hartley is that the former has two capacitive reactances
and one inductive one as principal components of its tank,
while the latter has L's where the former had C's and vice-
versa. In my mind, the fact that the Hartley inductors might
be coupled is just a minor variant.
Those criteria are vague, anyway. A capacitor in series with
the Colpitts inductor and it turns into a Clapp. Choose the
node between the two capacitors of a Colpitts for GND and
suddenly it gets called a Pierce. What if I do both?
There so many ways to make oscillators and only a few
names to choose from.
Jeroen Belleman
P
piglet
Guest
On 07/01/2020 23:54, Klaus Kragelund wrote:
This may be the kind of off-label usage where simulation differs from
real-life. In the 1960s folk made one-transistor bugs where the ca.
100MHz oscillator transistor base was jiggled up and down by the
microphone signal - even microvolts audio made kHz of deviation.
piglet
This may be the kind of off-label usage where simulation differs from
real-life. In the 1960s folk made one-transistor bugs where the ca.
100MHz oscillator transistor base was jiggled up and down by the
microphone signal - even microvolts audio made kHz of deviation.
piglet
P
Phil Hobbs
Guest
On 2020-01-08 03:42, Jeroen Belleman wrote:
Coupled inductors give you some autotransformer action, which makes the
impedance-transforming behaviour of the tank circuit work better,
especially at lower loaded Q. A Colpitts has only the tank Q to enforce
the impedance transformation, and so falls apart at Q values where a
Hartley is still working fine.
There's nothing analogous for capacitors, of course, so without mutual
inductance there's little difference between tapping down the
capacitance or the inductance.
I've never been a big fan of minute classifications of oscillator types
either, except for Hartley vs. Colpitts. The practical distinctions
have a lot more to do with things like tank impedance (especially with
crystals) and the effect of bias resistors on Q--in a Colpitts the base
bias string shunts the whole tank, whereas in some others it just shunts
part of it. Even there, if you use n*V_BE biasing (C-B feedback at DC,
emitter at DC ground), you can jack the impedance of the bias string way
up compared with the usual CE bias network.
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
Coupled inductors give you some autotransformer action, which makes the
impedance-transforming behaviour of the tank circuit work better,
especially at lower loaded Q. A Colpitts has only the tank Q to enforce
the impedance transformation, and so falls apart at Q values where a
Hartley is still working fine.
There's nothing analogous for capacitors, of course, so without mutual
inductance there's little difference between tapping down the
capacitance or the inductance.
I've never been a big fan of minute classifications of oscillator types
either, except for Hartley vs. Colpitts. The practical distinctions
have a lot more to do with things like tank impedance (especially with
crystals) and the effect of bias resistors on Q--in a Colpitts the base
bias string shunts the whole tank, whereas in some others it just shunts
part of it. Even there, if you use n*V_BE biasing (C-B feedback at DC,
emitter at DC ground), you can jack the impedance of the bias string way
up compared with the usual CE bias network.
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
Steve Wilson
Guest
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
A Colpitts runs fine at Q=1, as demonstrated by the vigorous parasitic
oscillations commonly found.
I doubt a Hartley with a coupling coefficient less than 1 would oscillate
as strongly.
Version 4
SHEET 1 880 708
WIRE -96 -112 -160 -112
WIRE -32 -112 -96 -112
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SYMATTR Value 5V
SYMATTR SpiceLine Rser=0
SYMBOL npn -224 -80 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL cap -352 -16 R0
SYMATTR InstName C1
SYMATTR Value 1.2732nF
SYMBOL cap -352 80 R0
SYMATTR InstName C2
SYMATTR Value 1.2732nF
SYMBOL ind -400 -16 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
WINDOW 39 -16 53 VBottom 2
SYMATTR InstName L1
SYMATTR Value 1.5915uh
SYMATTR SpiceLine Rser=50
SYMBOL voltage -608 -16 R0
WINDOW 123 0 0 Left 2
WINDOW 0 33 33 Left 2
WINDOW 3 33 80 Left 2
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SYMATTR Value 2.5V
SYMATTR SpiceLine Rser=0
SYMBOL res -176 64 R0
SYMATTR InstName R1
SYMATTR Value 560
TEXT -408 -240 Left 2 !.tran 0 20u 0 50p
TEXT -408 -264 Left 2 ;'Colpitts Q=1
A Colpitts runs fine at Q=1, as demonstrated by the vigorous parasitic
oscillations commonly found.
I doubt a Hartley with a coupling coefficient less than 1 would oscillate
as strongly.
Version 4
SHEET 1 880 708
WIRE -96 -112 -160 -112
WIRE -32 -112 -96 -112
WIRE -32 -96 -32 -112
WIRE -160 -80 -160 -112
WIRE -576 -32 -608 -32
WIRE -496 -32 -576 -32
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WIRE -160 64 -336 64
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FLAG -336 160 0
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FLAG -608 96 0
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SYMBOL npn -224 -80 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL cap -352 -16 R0
SYMATTR InstName C1
SYMATTR Value 1.2732nF
SYMBOL cap -352 80 R0
SYMATTR InstName C2
SYMATTR Value 1.2732nF
SYMBOL ind -400 -16 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
WINDOW 39 -16 53 VBottom 2
SYMATTR InstName L1
SYMATTR Value 1.5915uh
SYMATTR SpiceLine Rser=50
SYMBOL voltage -608 -16 R0
WINDOW 123 0 0 Left 2
WINDOW 0 33 33 Left 2
WINDOW 3 33 80 Left 2
SYMATTR InstName V1
SYMATTR Value 2.5V
SYMATTR SpiceLine Rser=0
SYMBOL res -176 64 R0
SYMATTR InstName R1
SYMATTR Value 560
TEXT -408 -240 Left 2 !.tran 0 20u 0 50p
TEXT -408 -264 Left 2 ;'Colpitts Q=1
S
Steve Wilson
Guest
Steve Wilson <no@spam.com> wrote:
The Colpitts runs fine at Q=0.25
Change Rser in my previous post to 200 ohms and R1 to 50 ohms.
XL = 2 * pi * 1.59e-6 * 5e6 = 49.9513231921 ohms
Q = XL / R = 50/200 = 0.25
The Colpitts runs fine at Q=0.25
Change Rser in my previous post to 200 ohms and R1 to 50 ohms.
XL = 2 * pi * 1.59e-6 * 5e6 = 49.9513231921 ohms
Q = XL / R = 50/200 = 0.25
P
Phil Hobbs
Guest
On 2020-01-08 09:41, Steve Wilson wrote:
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
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
Steve Wilson
Guest
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
Troll.
You used "fine" first: "where a Hartley is still working fine." So you are
criticizing yourself.
There is nothing wrong with the operation of the Colpitts. It starts at
very low amplitude and increases exponentially until it reaches the maximum
amplitude. This is determined by the current through the emitter resistor.
The frequency is determined by the LC product, with an offset due to the
low Q of the tank. See Chapter 9. Tuned Circuits, Equation 3, Page 449, in
the Radiotron Designers Handbook, 1954 edition, at
<http://preview.tinyurl.com/hmnpj2r>
The Colpitts is operating normally in every sense of the word.
However, you are completely missing the significance of these demos. They
show the Colpitts is perfectly capable of oscillating with extremely low Q
tanks, such as in parasitic oscillations. This is why you should provide
for base suppression resistors or beads for any circuit that may be capable
of parasitic oscillations. See the Readme.txt file for 02.ASC Colpitts Q=1
in Oscillator.zip at
https://drive.google.com/open?id=1ZsbpkV0aaKS5LURIb1dfu_ndshsSaYtf
Troll.
You used "fine" first: "where a Hartley is still working fine." So you are
criticizing yourself.
There is nothing wrong with the operation of the Colpitts. It starts at
very low amplitude and increases exponentially until it reaches the maximum
amplitude. This is determined by the current through the emitter resistor.
The frequency is determined by the LC product, with an offset due to the
low Q of the tank. See Chapter 9. Tuned Circuits, Equation 3, Page 449, in
the Radiotron Designers Handbook, 1954 edition, at
<http://preview.tinyurl.com/hmnpj2r>
The Colpitts is operating normally in every sense of the word.
However, you are completely missing the significance of these demos. They
show the Colpitts is perfectly capable of oscillating with extremely low Q
tanks, such as in parasitic oscillations. This is why you should provide
for base suppression resistors or beads for any circuit that may be capable
of parasitic oscillations. See the Readme.txt file for 02.ASC Colpitts Q=1
in Oscillator.zip at
https://drive.google.com/open?id=1ZsbpkV0aaKS5LURIb1dfu_ndshsSaYtf