Crystal Controlled Oscillator...

[Jan Panteltje]

On a sunny day (Sat, 8 Jan 2022 22:54:49 +1100) it happened Clifford Heath
<no.spam@please.net> wrote in
<16c84983409d8315$1$197710$66dd6c6a@news.thecubenet.com>:

On 8/1/22 6:23 pm, Jan Panteltje wrote:
I also have some ultrasonic distance meter modules from ebay, something like this:
https://www.ebay.com/itm/322948018241
those have some special chip and a crystal.
Cheap way to get transducers

Pretty sure that\'s a version of one of Gerry\'s designs.

Now I just received some about 3 GHz? (still have to measure it) doppler motion detectors that work through glass etc.

There\'s a bunch of new 24GHz ones too, things like this are all over
AliExpress: <https://www.aliexpress.com/item/4000057318135.html

Clifford Heath

Thanks
have bookmarked it

 

[Jan Panteltje]

On a sunny day (Sat, 08 Jan 2022 11:43:11 +0100) it happened Jeroen Belleman
<jeroen@nospam.please> wrote in <srbprv$7t5$1@gioia.aioe.org>:

On 2022-01-08 10:53, Jan Panteltje wrote:
PS
see
https://github.com/jdesbonnet/RCWL-0516

Now I just received some about 3 GHz? (still have to measure it) doppler motion detectors that work through glass etc.
from a local shop, also for about 2 Euro a piece, on ebay those are even cheaper:
https://www.ebay.com/itm/311911747154
Is using that frequency even legal here?
Plenty of stuff play with!



Interesting gadget. I suppose Q1 does double duty as oscillator
and mixer. The schematics are of no help to figure out how it
really works. Anyone care to comment? The secret is all in the
PCB layout around Q1, clearly.

Also, it doesn\'t look like this thing could work for years on
a little battery, like some PIR detectors do.

Jeroen Belleman

I have a big PIR detector that was above the garden door of the old house,
and would start security cams if anybody came up to the house.
But it requires 12 V, and I do not want to drill a hole here and install it
so want to try this one through the glass of the front door.
I will get power from the PC UPS for now.
But first I will experiment with it a bit!

 

[piglet]

On 08/01/2022 02:04, Artist wrote:

Why not a circuit similar to this self excited one used for the muRata
piezoelectric microblower:

https://www.mouser.com/pdfdocs/MurataMicroblowerDriverInfo.pdf

?

The op amp I would use instead is the OPA552P. It is known this has the
bandwidth, and the output power, to do the job. I would, therefore, not
need the buffering transistors.

To determine a compensation network I recognize I will need to
characterize the piezo electric actuator either with a resistor, and a
function generator, or a network analyzer if we have one. It may be that
it won\'t need one due to there being no buffering transistors.

Depending on your piezo device there could be chance of that circuit
oscillating on some mode or overtone but that circuit is simple enough
you could breadboard it and try inside an hour?

piglet

 

[piglet]

On 08/01/2022 10:43, Jeroen Belleman wrote:

On 2022-01-08 10:53, Jan Panteltje wrote:
PS
see
   https://github.com/jdesbonnet/RCWL-0516

Now I just received some about 3 GHz? (still have to measure it)
doppler motion detectors that work through glass etc.
from a local shop, also for about 2 Euro a piece, on ebay those are
even cheaper:
https://www.ebay.com/itm/311911747154
  Is using that frequency even legal here?
Plenty of stuff play with!



Interesting gadget. I suppose Q1 does double duty as oscillator
and mixer. The schematics are of no help to figure out how it
really works. Anyone care to comment? The secret is all in the
PCB layout around Q1, clearly.

Also, it doesn\'t look like this thing could work for years on
a little battery, like some PIR detectors do.

Jeroen Belleman

Yes the oscillator transistor is also the receiver/mixer. Kinda like a
grid dip oscillator or the front end of a WW2 proximity fuze.

As motion detectors they also respond to drapery or foliage movement
unlike PIR which only react to moving thermal emitters, that can make
those microwave motion detectors useless in some applications.

piglet

 

[Clifford Heath]

On 8/1/22 9:43 pm, Jeroen Belleman wrote:

On 2022-01-08 10:53, Jan Panteltje wrote:
PS
see
   https://github.com/jdesbonnet/RCWL-0516

Now I just received some about 3 GHz? (still have to measure it)
doppler motion detectors that work through glass etc.
from a local shop, also for about 2 Euro a piece, on ebay those are
even cheaper:
https://www.ebay.com/itm/311911747154
  Is using that frequency even legal here?
Plenty of stuff play with!



Interesting gadget. I suppose Q1 does double duty as oscillator
and mixer. The schematics are of no help to figure out how it
really works. Anyone care to comment? The secret is all in the
PCB layout around Q1, clearly.

I believe it\'s the same approach that used to be used by the 10GHz
automatic door detectors that used to trigger automotive radar
detectors. Oscillator and mixer in one device, pick out the audio
Doppler signal.

CH

 

[Jeroen Belleman]

On 2022-01-09 00:51, Clifford Heath wrote:

On 8/1/22 9:43 pm, Jeroen Belleman wrote:
On 2022-01-08 10:53, Jan Panteltje wrote:
PS see https://github.com/jdesbonnet/RCWL-0516

Now I just received some about 3 GHz? (still have to measure
it) doppler motion detectors that work through glass etc. from
a local shop, also for about 2 Euro a piece, on ebay those are
even cheaper: https://www.ebay.com/itm/311911747154 Is using
that frequency even legal here? Plenty of stuff play with!



Interesting gadget. I suppose Q1 does double duty as oscillator and
mixer. The schematics are of no help to figure out how it really
works. Anyone care to comment? The secret is all in the PCB layout
around Q1, clearly.

I believe it\'s the same approach that used to be used by the 10GHz
automatic door detectors that used to trigger automotive radar
detectors. Oscillator and mixer in one device, pick out the audio
Doppler signal.

CH

I gathered that much, yes. I was more interested in a discussion
of the PCB traces and how they work together to make an oscillator
and antenna.

I\'m trying to guess the signs of the reactances between the
terminals of Q1 at 3GHz. The trouble is that everything is
coupled to everything else and I\'m at a loss to tell what
is dominant. Every damn bit of trace around Q1 looks like
a resonator that could be either capacitive or inductive at
3GHz!

At least I\'m convinced that none of the actual /components/
on the schematic are involved in determining this oscillator.
(Except for Q1, of course.) It\'s all in the PCB traces.

Jeroen Belleman

 

[Rich S]

On Wednesday, January 5, 2022 at 6:15:37 AM UTC, Artist wrote:

The driven waveform must be sinusoidal. Purity is not critical. It can
be somewhat ragged.

A way to detect phase I am considering is to use comparators to convert
sinewave to square wave, and then detect phase difference in the similar
way the CD4046 does. The logic would have to be more complex than just
an exclusive OR gate though, because the XOR adjusts phase to 90 degrees.

I have trouble finding a successor to the EOL XR-2206. Suggestions would
be appreciated. If I do not find one I may have to try self excitation.

As a solution purely to generate a sinewave
between 70 - 8kHz, in a \"drop in\" strategy,
I would consider either

1. Microchip RE46Cxxx \"Piezoelectric Horn Driver\" IC
with LC tank on output to approx. the sinewave

2. replacements for electronic-synthesizer chips
a VCO like the CEM3340
https://www.ericasynths.lv/shop/ics/voltage-controlled-oscillator-as3340/
or a VCF in self-resonance oscillation
SSI2144
https://www.soundsemiconductor.com/

 

[Anthony William Sloman]

On Monday, January 10, 2022 at 12:41:06 PM UTC+11, Rich S wrote:

On Wednesday, January 5, 2022 at 6:15:37 AM UTC, Artist wrote:
The driven waveform must be sinusoidal. Purity is not critical. It can
be somewhat ragged.

A way to detect phase I am considering is to use comparators to convert
sinewave to square wave, and then detect phase difference in the similar
way the CD4046 does. The logic would have to be more complex than just
an exclusive OR gate though, because the XOR adjusts phase to 90 degrees.

I have trouble finding a successor to the EOL XR-2206. Suggestions would
be appreciated. If I do not find one I may have to try self excitation.
As a solution purely to generate a sinewave
between 70 - 8kHz, in a \"drop in\" strategy,
I would consider either

1. Microchip RE46Cxxx \"Piezoelectric Horn Driver\" IC
with LC tank on output to approx. the sinewave

2. replacements for electronic-synthesizer chips
a VCO like the CEM3340
https://www.ericasynths.lv/shop/ics/voltage-controlled-oscillator-as3340/
or a VCF in self-resonance oscillation
SSI2144
https://www.soundsemiconductor.com/

All of this depends on more or less knowing what you are doing, and Artist doesn\'t seem to have got there yet, and seems resistant to suggestions that might get him to a state where he might get closer to understanding what he is actually trying to do. At the moment what he seems to want is a drop-in replacement for the XR-2206 which produced pretty poor sine waves (by rounding off a triangular wave) and had to be trimmed to get the right drive frequency for each different actuator. It wasn\'t a good solution when it was chosen. He should be able to do better, but doesn\'t seem to realise that he could, or be all that interested in finding out how.

--
Bill Sloman, Sydney

 

[Chris Jones]

On 06/01/2022 02:31, Phil Hobbs wrote:

Artist wrote:
The driven waveform must be sinusoidal. Purity is not critical. It can
be somewhat ragged.

A way to detect phase I am considering is to use comparators to
convert sinewave to square wave, and then detect phase difference in
the similar way the CD4046 does. The logic would have to be more
complex than just an exclusive OR gate though, because the XOR adjusts
phase to 90 degrees.

I have trouble finding a successor to the EOL XR-2206. Suggestions
would be appreciated. If I do not find one I may have to try self
excitation.

A filtered square wave, or (for fun) a 74HC4017 and some weighted
resistors.  We had a thread on that awhile back--2011, it was.  The OP
was George Herold.  (George? You still out there, man?)

https://groups.google.com/g/sci.electronics.design/c/sZWMknd6yjw/m/8HdJPZFUriAJ


Cheers

Phil Hobbs

It sounds like the product is not very cost-sensitive.

There are pretty cheap DDS chips these days (AD9837 $2), which might
solve the problem of generating the waveform well.

Something like the AD5933, AD5934 could also measure the impedance of
the transducer and a micro could use this for adjusting the tuning. This
is what I would do.

 

[Phil Hobbs]

Chris Jones wrote:

On 06/01/2022 02:31, Phil Hobbs wrote:
Artist wrote:
The driven waveform must be sinusoidal. Purity is not critical. It
can be somewhat ragged.

A way to detect phase I am considering is to use comparators to
convert sinewave to square wave, and then detect phase difference in
the similar way the CD4046 does. The logic would have to be more
complex than just an exclusive OR gate though, because the XOR
adjusts phase to 90 degrees.

I have trouble finding a successor to the EOL XR-2206. Suggestions
would be appreciated. If I do not find one I may have to try self
excitation.

A filtered square wave, or (for fun) a 74HC4017 and some weighted
resistors.  We had a thread on that awhile back--2011, it was.  The OP
was George Herold.  (George? You still out there, man?)

https://groups.google.com/g/sci.electronics.design/c/sZWMknd6yjw/m/8HdJPZFUriAJ


It sounds like the product is not very cost-sensitive.

There are pretty cheap DDS chips these days (AD9837 $2), which might
solve the problem of generating the waveform well.

Something like the AD5933, AD5934 could also measure the impedance of
the transducer and a micro could use this for adjusting the tuning. This
is what I would do.

I suspect that the technological impedance mismatch might be a bit of an
issue--the previous version used an XR2206!

(Nice part though.)

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

 

[John Larkin]

On Fri, 7 Jan 2022 18:04:58 -0800, Artist <sepflanze@sj.gmail.com>
wrote:

Why not a circuit similar to this self excited one used for the muRata
piezoelectric microblower:

https://www.mouser.com/pdfdocs/MurataMicroblowerDriverInfo.pdf

?

The op amp I would use instead is the OPA552P. It is known this has the
bandwidth, and the output power, to do the job. I would, therefore, not
need the buffering transistors.

To determine a compensation network I recognize I will need to
characterize the piezo electric actuator either with a resistor, and a
function generator, or a network analyzer if we have one. It may be that
it won\'t need one due to there being no buffering transistors.

If the resonant load has a reasonable Q, you could drive it with a
square wave in a self-oscillating circuit. One simple IC and a few
passives might do it.



--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[Anthony William Sloman]

On Tuesday, January 11, 2022 at 6:09:08 AM UTC+11, John Larkin wrote:

On Fri, 7 Jan 2022 18:04:58 -0800, Artist <sepf...@sj.gmail.com
wrote:
Why not a circuit similar to this self excited one used for the muRata
piezoelectric microblower:

https://www.mouser.com/pdfdocs/MurataMicroblowerDriverInfo.pdf
The op amp I would use instead is the OPA552P. It is known this has the
bandwidth, and the output power, to do the job. I would, therefore, not
need the buffering transistors.

To determine a compensation network I recognize I will need to
characterize the piezo electric actuator either with a resistor, and a
function generator, or a network analyzer if we have one. It may be that
it won\'t need one due to there being no buffering transistors.

If the resonant load has a reasonable Q, you could drive it with a square wave in a self-oscillating circuit. One simple IC and a few passives might do it.

A \"modifed sine wave\" would be almost as simple and would get rid of the third harmonic component. The OP didn\'t like that idea ether.

His actuator produces a optical scan, and he\'d prefer that it generated a smooth scan, but he\'s not up to specifying how smooth a scan he might need, and he clearly isn\'t up to monitoring how smooth it might be.

--
Bill Sloman, Sydney