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
Crystal Controlled Oscillator
Started by ●January 3, 2022
Reply by ●January 8, 20222022-01-08
Reply by ●January 8, 20222022-01-08
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
Reply by ●January 8, 20222022-01-08
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 HeathThanks have bookmarked it
Reply by ●January 8, 20222022-01-08
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 BellemanI 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!
Reply by ●January 8, 20222022-01-08
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
Reply by ●January 8, 20222022-01-08
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 BellemanYes 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
Reply by ●January 8, 20222022-01-08
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
Reply by ●January 9, 20222022-01-09
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. > > CHI 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
Reply by ●January 9, 20222022-01-09
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/
Reply by ●January 9, 20222022-01-09
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
