Solar "radar" light control module - with schematic (and fix!)

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The peril of making videos late at night. I completely screwed up the frequency by a significant factor. The 5ns waveform is around 200MHz (0.2GHz), so it could be the oscillator frequency.
A fairly standard style of module used in solar powered lighting systems. The circuit board has a very intriguing mix of RF, analogue and digital circuitry.
Having reverse engineered the design without testing it first, it was a bit annoying to find out that it was faulty. But it was a good excuse to scope out the filtered doppler waveform.
Not sure what was causing the specific frequency of the rogue waveform. It might have been a hybrid of the 300kHz switching 5V supply combined with an unstable RF oscillator to create a harmonic effect.
Seeing the bursts of low frequency doppler frequency shift was quite cool (if that's what it actually was). The fact it changed frequency with speed of objects approaching the oscillator does hint at doppler detection, where a signal reflection from a moving object will be at a slightly different frequency from the RF transmitter. In this case I think it disturbs the oscillators natural frequency and causes it to modulate its current draw.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- www.bigclive.c...
This also keeps the channel independent of RU-vid's algorithm quirks, allowing it to be a bit more dangerous and naughty.
#ElectronicsCreators

Опубликовано:

29 сен 2024

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Комментарии : 158

@davidrichter57 3 месяца назад

Meh, nanoseconds vs. milliseconds. What's six orders of magnitude between friends?

@rimmersbryggeri 3 месяца назад

It depends if you are measuring from the root or from the asshole. 🤣 OR maybe that is meters rather than seconds?

@snakezdewiggle6084 3 месяца назад

But that statement is incorrect. Have a little think about it.

@Deipnosophist_the_Gastronomer 3 месяца назад

20 Aspro a day takes a man's pain away

@timonarthur 3 месяца назад

micro.

@DavidLessem 3 месяца назад

I have a million friends who could answer the question, but he's out of town.

@kevin30b90 3 месяца назад

What an adventure! Going through this circuit has been totally captivating. Thank you for being the guide 😊. You clearly had quite a challenge putting this description together 👍

@Uncle-Duncan-Shack 3 месяца назад

Very interesting, I enjoyed the video. Note that these will go deaf around wifi routers as the router emissions do drown out the doppler signals. A few meters of separation is normally good enought o fix that. Appreciate the effort that went into this one.

@markfergerson2145 3 месяца назад

Yeah, good old fashioned front end capture. It’s a consequence of the 5GHz band having to be shared by devices that do different things, and (in the US) one of them having to accept interference by the other.

@A65Bill 2 месяца назад

I have read all the comments after watching the video twice & now realise i am an Expert! I verified this status by a simple process of rating my grasp of the technology at each point in the design. Zero across the board and an overall average of nil on my scorecard is worthy of note. Nonetheless i enjoyed it all thanks Clive & all.

@terrym1065 3 месяца назад

👍👍 Good job Clive, thank you.

@ricoma6037 3 месяца назад

You continue to demonstrate your brilliance with our appreciation!

@Mike_Hughes 2 месяца назад

I'm sorry Clive, I fell asleep (repeatedly), every time you got to 'nano seconds'... I just can't help it. You are clearly brilliant though, I wish we could meet, so that I could learn more... Keep up the good work, regards, Mike

@TonyLing 3 месяца назад

Good job Clive, thank you for your service Sir

@KarldorisLambley 3 месяца назад

i am too tight to pay for a TV license, and i never watch YT ads. but i'll gladly contribute to your work.

@bigclivedotcom 3 месяца назад

Thanks.

@kevtris 3 месяца назад

the rf section reminds me a lot of a regenerative receiver, where you monitor the current draw to pick off the received signal. I guess this is not much different than this- it is just receiving its own signal after it bounces off something.

@TechyBen 3 месяца назад

There's an amazing animation of a solid state beam steering antenna. Can be made similar to the traces there, but is a weird asterisk shape: * . Slow mode field animation shows if you send signal/power to one side not the other it "forms" the beam to point in the other direction, and likewise can fill each finger with more or less power/pulsed waves to shape it's direction. I wonder if those through holes help shape the direction?

@petehiggins33 3 месяца назад

I don't think that 2.5kHz signal is meant to be there at all, it's a spurious oscillation of the band pass filter (the left hand op amp). The output of this op amp is supposed to be a dc level at half the supply voltage when there's no movement. The threshold of the comparator (the right hand op amp) is about 0.12V below that dc level. So any low frequency Doppler frequency that gets through the band pass filter larger than 0.12V will be detected and turn the light on. The presence of the large 2.5kHz oscillation will produce continuous output and prevent it from working. By attenuating the spurious signal you have prevented this from happening and allowed movement to be detected. The bodge capacitor was probably and attempt to stop the spurious oscillation.

@rarbiart 4 месяца назад

"There are advantages on the doppler, especially if it's working"

@Clark-Mills 3 месяца назад

2:06 Are the resistors in parallel or series? Your photo looks like parallel but could easily be deceiving me... Irrespective, many thanks for your continued work... It's all greatly appreciated. [edit] Ah watched a bit further... 4:13 they are in parallel, thanks!

@LutzSchafer 3 месяца назад

It's milliseconds 😆 Clive and not Doppler radar. For this you would need two parch antennas. The RF circuit is just an oscillator. Someone analyzed it years ago. Guess you need to Google for it. I believe what you saw was interference with the reflected wave.

@zh84 4 месяца назад

Curious Marc calls microwave circuitry "the blackest of black arts in analogue electronics". If anyone who enjoys Big Clive's teardowns and explanations of electronics ISN'T subscribed to Curious Marc, I suggest they look him up. There is a magnificent stage-by-stage analysis of how data, voice, telemetry, television and more was encoded and decoded into a single signal sent back from the Apollo capsules to Earth during the Moon missions.

@phonotical 4 месяца назад

He would, it doesn't take a genius to work it out

@misterhat5823 3 месяца назад

Years ago I went for a job interview at RF Micro. The lead engineer called 100MHz "practically DC."

@twocvbloke 3 месяца назад

As long as it provides a Homer Simpson "Light goes on, light goes off, light goes on, light goes off!" level of entertainment, then that's what matters... :P

@andrewsmythe-lg5ce 3 месяца назад

It's doppler, Andreas tested some, but what's the nighttime standby drain like? I have some modules, but they greedy, I forget the drain, but not suitable for battery powered home automation, which is a shame. There are some quite advanced programmable ones now, I believe they can detect your chest raising and lowering as you breathe at night while asleep, which makes a perfect presence detector, finally.

@bigclivedotcom 3 месяца назад

The standby current is definitely significant compared to PIR.

@CrazyOregonBeaver 4 месяца назад

I wonder if you could use it for a proximity fuse for your ground to air missile. Maybe your next video. 😂😂😂

@stevebabiak6997 3 месяца назад

2:07 - “… three one ohm resistors in parallel to give about 3.3 ohms …” Please try that one again: three one ohm resistors in parallel will give about 0.33 ohms, whereas three one ohm resistors in series will give about 3 ohms.

@Richardincancale 3 месяца назад

Next step - download and disassemble the code in the microprocessor!

@bigclivedotcom 3 месяца назад

Unknown processor and probably locked.

@tonyweavers4292 4 месяца назад

Meanwhile, somewhere in China... "Ah Big Clive he fix our module, we need put capacitor back"

@dashcamandy2242 3 месяца назад

If it's not true Doppler, would it be appropriate to call it a Dopplerganger? 🤣

@ulrikesteinkogler4755 3 месяца назад

Sonst aber meisterhaft!

@HytelGrp 3 месяца назад

Hi Clive, We called that area by B a tuning stub when I worked at Motorola. You design the capacitor values as needed, but because of capacitor and high frequency part tolerances you need to match the capacitance to the high frequency part. We used a laser to remove a small amount of metal to 'tune' the circuit to the exact frequency. The squiggly track is also to match the impedance of the circuit to the antenna (VSWR) to deliver maximum power to the antenna (or from, in this case), and it is a simple formula of frequency to a single sign wave (2 kHz = a wavelength of 35 cm). It reduces the tract length (from straight, as in an collapsible FM radio antenna) by zig-zagging it on the substrate.

@markfergerson2145 3 месяца назад

Yep. That stub in combination with the ground plane next to it *and* the ground plane under it form a tuned circuit making the basis of a single-transistor RF oscillator. The squiggly bit is the antenna + z matcher in one piece. It’s not really that simple of course- the resonator and the antenna/matcher interact too kind of like a tuned-plate tuned- grid tube oscillator works but the coupling isn’t as strong, until someone walks by and it is. Anyway, Clive is right, it’s a Doppler detector. Reflected RF adds to or subtracts from the current in the antenna and the difference gets passively filtered and sent to the active low pass filter about which he is also correct.

@snakezdewiggle6084 3 месяца назад

@HytelGrp "Tract" vs Track.

@Mike_Hughes 2 месяца назад

Clever Bugger, I'm impressed, honestly. I keep learning things that I don't quite understand... er, completely.

@EShirako 2 месяца назад

Wow, even trimming it off with LASERS! That's finicky! I'm impressed. I knew RF analog was a bit of a trick but I hadn't realized it was that much of a trick.

@snakezdewiggle6084 2 месяца назад

@HytelGrp The Wavelength of 2kHz = 149,.896 Kilometres. What is VSWR.

@nate_0723 3 месяца назад

RF is a black art - even to RF experts.

@sometimesleela5947 3 месяца назад

It's true; alot of rf guys I know 'cheat' by watching a scope while adding components rather than just designing it so it should work in the first place.

@Qwarzz 3 месяца назад

@@sometimesleela5947 Are you saying RF stuff can actually be designed instead of just stumbling upon a working configuration? :)

@oliverer3 3 месяца назад

@@QwarzzYou can kinda design qualified guesses xD

@iaov 3 месяца назад

We called it PFM…. Pure f&$cking magic!

@BB-iq4su 3 месяца назад

All geometry with unknown parasitics....

@dascandy 4 месяца назад

err, 3 1ohm resistors in parallel seems to be 0.33 ohm? @2:10 . Also, around @11:22 you have "0.5 nanoseconds is about 2 kilohertz". I think you misread the "ms" as "ns"?

@n-steam 3 месяца назад

He's reviewed so many chinese electronics, he's began to use their accuracy.

@joeboatwrench9315 4 месяца назад

Thank you Clive. We all are hoping that hand is healing up well. Burns can be problematical especially on busy hands.

@Simplyrecovery 3 месяца назад

Very bright guy our clive. Well impressed with his knowledge.

@piconano 3 месяца назад

This module was inspired by the RCWL-0516 module. That one operates at 3.2 GHz. Didn't think they could make it cheaper? They did. They eliminated the need for that chip, with clever filtering and amp section.

@BanzaiFU2 3 месяца назад

I concur..I use the "cheap like borscht" RCWL-0516 units with a FET to switch on LEDS, alarms, etc.

@hubertnnn 3 месяца назад

Wouldn't a single chip be cheaper than 5 layers of filtering?

@piconano 3 месяца назад

@@hubertnnn Good point. LM358 is cheaper than dirt. So are resistors and caps. I don't know the costs, but given the way Chinese operate, I wouldn't be surprised if they came across tons of these Op Amps on the cheap, and designed around them. They do that for all through hole components which have no market left since SMD.

@jaro6985 2 месяца назад

@@hubertnnn LM358 can be had for 1.5c each, 10 passives cost maybe 1c. So you are competing with a cost of ~3c.

@simontillson482 3 месяца назад

Don’t doubt yourself, Clive! You had it right the first time. It clearly says 0.2 milli seconds per div on the scope image, which makes the frequency 2kHz ish. If it was 0.2 nano seconds, the frequency would have been 2 gigahertz. By the way, doppler frequency is about 20Hz per m/s, so a waving hand might give 50 to 150Hz, and a swaying Clive closer to 30Hz. Not sure if this makes a case for or against it using doppler shift, but considering it only uses an audio-frequency low pass filter, I’m leaning towards yes - I can’t imagine how an LM358 could respond to any kind of reflected power ratio measurement, cos it would have to be operating at RF frequency to do that, or at least have an RF detector (diode and cap integrator?) as the front end, rather than the low pass filter. Then again, if we guess that it’s operating around 5GHz or so, the reflected wave would interfere with the transmitted one in a varying way as objects moved in its vicinity. Nah… that would have no effect on the oscillator - it would be way too tiny. I’m sticking with doppler, via mixing of the transmitted and received waves generating a doppler difference frequency.

@lmamakos 3 месяца назад

I've played around with standalone versions of these "doppler radar motion detectors" and I believe they are doppler based. That one transistor oscillator is working pretty hard, and also serves as a mixer for the signals that are bounced back from nearby targets. Their shifted frequency based on the motion of the object causes the low-frequency mixing product to be generated and detected in that "audio" region.

@markfergerson2145 3 месяца назад

It definitely is Doppler. What you’re missing is that the outgoing and incoming signals are mixed in the antenna (the squiggly trace) and the low frequency sum and difference are what the passive LC filter sees, and its output goes to the active low pass filter. A swaying Clive should be more in the .3-3Hz neighborhood…

@phonotical 4 месяца назад

Don't think it's doppler, I think it's a bad self feedback, which your waveform suggests also, being in a constant state

@andreasdill4329 3 месяца назад

The question-mark cap may be coupled to the antenna to give a feedback to the base of the transistor to get the circuit to oscillate. Reflected RF will then be mixed by the same transistor. The doppler frequency is then filtered by the first op-amp. This is a typical bandpass, It will be tuned to pick out the typical frequency's made by objects moving at human typical speed. To filter out flying bugs.

@inseries5494 3 месяца назад

The opamp with RC network shown is a typical band pass filter

@SirBoden 3 месяца назад

Analog RF posse reporting Sir 🫡 It is Doppler shift sensing a low frequency RF signal ~2kHz. The length and shape of the antenna gives it away. 🙂

@rarbiart 4 месяца назад

incredible what technology we can get for a small buck nowadays.

@Zadster 3 месяца назад

Multi-path interference. Basically heterodyning itself but with slightly different phases, the result of which is a low frequency signal. The difference in signal path is doing the work, not the speed of movement (doppler).

@LutzSchafer 3 месяца назад

It likely is just constructive/destructive interference with the reflected wave. For mixing (heterodyne) you need multiplication. Such nonlinearity is not given in this simple circuit.

@JoseSilveira-newhandleforYT 3 месяца назад

Interesting little circuit! My experience with "radar" detectors is a bit unusual - I installed one on my balcony light, outside the room I have the PC, so that I could note when people passed by at night. I found out that it was able to sense across the wall and trigger on any movement I made, inside the house! This was easy to fix with a grounded metal plate, but I didn't bother. It's still there, but I disconnected its power - that's how lazy I became :-)

@iamfubar1 4 месяца назад

Nice workaround for fixing a bad module :)

@ms2649 3 месяца назад

I really love the longer/complex ones. Its fascinating to see how those boards work, especially with how well you explain all part but keep it simple at the same time ❤.

@snakezdewiggle6084 3 месяца назад

Yeah, but does it come Pink?!😆 RF is easier than AC. Clive, you would pick it up in about 20hrs. Rule of thumb. 1. All RF circuits are either, a filter, or an amplifier, or a mix of both.

@roysigurdkarlsbakk3842 3 месяца назад

That was milliseconds, not nanoseconds. If you had .5ns wavelength of that thing, it'd be at 2GHz

@rarbiart 4 месяца назад

11:25 i assume it's 0.2ms on the photo. so 2k5kHz is right (the device will probably not get that resolution on 2,5GHz ;-)

@tazz1669 4 месяца назад

Thanks Clive, sounds like it took a long time to get this one reverse engineered

@starlights50 3 месяца назад

Ya think! Yay BC

@iaov 3 месяца назад

very cool Clive. Thanks for sharing ❤️

@rexsceleratorum1632 3 месяца назад

Pretty sure it's 5ms on a DSO "scope" scare quotes. You are not seeing microwaves.

@gregorythomas333 3 месяца назад

Wow...this is an extremely complicated board...very cool! Thank you for explaining it so well :)

@deltab9768 3 месяца назад

Quite a complex functioning circuit! It’s like a solid state version of the proximity fuzes used in WW2, plus a microcontroller to select different modes. I was surprised to see several of these online claiming 5 or 10 meter sensing range. Pretty significant for such a small, low cost and low powered unit. Well done with the reverse engineering!

@mrdovie47 3 месяца назад

I believe you have it right on Doppler. The microwave oscillator is so fast that even a slow reflected movement will change the frequency down to an audio signal not just a different RF signal. The opamp can pick this up and filter it to a DC level and trigger the light.

@raymitchell9736 3 месяца назад

I agree! RF is black magic. Good job sorting it out.

@jlucasound 3 месяца назад

@2:09 Aren't three 1 Ohm resistors in parallel .33 Ohms? Maybe I misunderstood you. I thought you said 3.3 Ohms. 🙂 OK, @4:15 you said .33. 🥰🤩

@demef758 3 месяца назад

Ain't no LM358 on this planet that can output a signal in the GHz region! It's 0.5 mS, or about 2 kHz, which the LM358 can certainly handle. Having said that, one well-known problem with an actual LM358 chip (not an updated LM358) was its awful totem pole output. If you bias the op amp in its mid range, as is the case here, then the output will have odd crossover distortion artifacts as the output tries to alternate between sink (PNP) and source (NPN) of currents to some light load. The fix is to add something like a 1 kohm resistor to ground on each output, which effectively biases the output so that the NPN output transistor in conjunction with the pulldown resistor are always supplying the output current. The PNP output transistor is then effectively cut off. Any newer updated version of the LM358 (which will never include "LM" in its name) fixes this known flaw in the opamp. Whenever I see any kind of design that uses an actual LM358 in it, it immediately tells me that the designer was not very experienced in linear design. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-VgodYtiD_F0.htmlsi=wK2MK04FJWuOPijM

@misterhat5823 3 месяца назад

The "splooge" capacitor is not a normal place for one. With some opamps, it could cause oscillations. The LM358 happens to not be normal under the hood and not very fast either, so all bets are off for why it's there.

@PaulSteMarie 2 месяца назад

Re that op amp feedback circuit, the main element is that cap going directly from out to -in. That drops the gain to unity for higher frequencies. The whole thing looks like an active low-pass filter. The input cap blocks DC and the voltage divider recenters the waveform at 2.5V.

@glasseffect 3 месяца назад

The PIR is ineffective with ambient temperatures around 48c, common in tropical regions. Doppler however is succeptible to false trigerring around water bodies and plants and trees.

@ryanmccarthy2033 3 месяца назад

I work at a place that sells fitness equiptment and we have a TM that is notorious for blowing the lower control board because of friction. I wonder if big clive would be interested in finding out why the boards are so junky straight from the factory. I wish i knew how to get ahold of him but im not great with computers. Its from a BH S5TIB. They used to be good TMs. We are stuck with a whole container of those and they are nightmarish for us

@angeldelvax7219 3 месяца назад

The wiggly track is actually the antenna. If I'm reading it correctly (I'm by no means an expert in this...) the antenna transmits a frequency, and when it receives the reflected signal, the interference on the antenna gets amplified by the op-amp circuit. The scope screen does look like it shows 0.2ms, but then, I didn't do the measuring, so you likely know best ;) But if the 2kHz is correct, it's 0.5ms, not ns. The filtering caps in the op-amp section, especially the one between the 1M resistors, might be used to vary amplification depending on the frequency.

@Simplyrecovery 3 месяца назад

I believe the track your referring to is an inductor, if you mean the one on the emmiter of Y2

@Simplyrecovery 3 месяца назад

Ooh I see the track you mean my bad, your absolutely correct, apologies

@karltest1314 3 месяца назад

Good tear-down. Never knew you could dopler rf, sure you dont mean phase shift detection?

@chuckmuziani6262 2 месяца назад

358 circuit looks like a bandpass and was maybe oscillating.

@hubertnnn 3 месяца назад

Excuse me, the filter on my filter's filter is not filtering. Could you add an extra filter on that filter?

@anon-means-anon 2 месяца назад

RF design is indistinguishable from magic.

@kellyeye7224 3 месяца назад

I'd say that copper pad is an inductor, not capacitor as it is a 'short' possibly forming a feedback circuit in an oscillating transmitter?

@TheCORC964 2 месяца назад

You should start a podcast, I love having your videos on in the background just for the background noise. And of course they’re informative and interesting too

@bigclivedotcom 2 месяца назад

There was a live stream channel on RU-vid, but I recently moved to Twitch due to problems with RU-vid. The twitch channel is also called bigclivedotcom.

@royshaft 3 месяца назад

These radar detectors rather than PIR are a real pain . I fitted a light with one built in , it sees you through the door in the hall , and even through the floor to the landing upstairs . The light is nearly always on because the cloakroom is dark and waiting for a trigger , which it almost constantly gets .

@mrgrumpy9077 3 месяца назад

Luckily not your right hand 🖐 😂

@BB-iq4su 3 месяца назад

In my garage I have a RaspberryPi server with a camera and Python code to send me, when image pixels change, photos to my email. I was overloaded with photos in my email. I put one of those RF detectors on the GPI and modified the code to only send email if the RF detected motion. It works just fine. I keep the extra images/movies on a thumb drive that are less than two weeks old. Each night a crontab schedule deletes old images. It's the best of my hobby projects yet. RF detectors are much better than PIR.

@starlights50 3 месяца назад

Waa. Neato

@nomusicrc 3 месяца назад

Why did you leave a blank page between the pages of the schematic What is Doppler

@bigclivedotcom 3 месяца назад

To stop the image coming through under the bright lights.

@stephenamor7762 3 месяца назад

Wow, that's not a BC108 then!

@waltahlgrim5508 3 месяца назад

The doppler we had sensed movement thru the wall, floors and ceiling. I was very confused for some time before I understood why the light was on so much.

@bigclivedotcom 3 месяца назад

And often stuff like trees moving outside too.

@t1d100 3 месяца назад

Just sharing a sneaky VS1838 Infrared Receiver Transistor failure, here, to get the word out... I was repairing a solar light, which was controlled by an IR remote control. I discovered that its 1838 was faulty, which was causing the MCU to keep the light switched off. Here's the sneaky part... I tested the transistor function of the 1838 with a multimeter and the transistor tested as working. The problem was that the 1838 looks for a 38KHz "modulation" signal from the IR transmitter (inside the remote control.) The 1838 had lost its ability to read that modulation signal. As said, sneaky, because the transistor function tested as working. Hope that helps someone. Cheers.

@GregBurrowa 3 месяца назад

2:08 in 3 one ohm in parallel?

@neilobusk 3 месяца назад

omg...doppler radar for solar lights...... so can like detect an incomming Russian Su 25 .....Su34 or Mig31... and light up my garden to warn me..... you soooo remind me of old electronics teacher... apart he had a white board... Top videooooo N x

@fredfred2363 3 месяца назад

If it is doppler, there'd be some sort of "mixer" on the pcb track. So imagine one part of the PCB oscillates generating an RF output (transmit beam if you like), and then the receive part of the same PCB has to interfere with the reflection signal. Or "mix". So the result would be a low frequency. Perhaps that 2kHz signal means the receive part of the PCB was "out". Instead of generating frequency bursts, it is probably meant to generate very low frequency pulses. Like on or off blips. Think of police radar detectors which use horns and precision cavity resonators. School "Young's slits wave experiments". What's the sensitivity range like?

@isoufacker 3 месяца назад

its a puzzle and a maze

@tniemi 3 месяца назад

"with schematic" Aw yiss, the good stuff! "and fix" That's the luxury!

@mazzg1966 3 месяца назад

Thanks Clive you rock!! We appreciate the work you put into your videos and reverse engineering, making it easier (but still very complicated) to understand. I find myself nodding like ya that makes total sense...but I am still totally clueless! Ha ha ha...Love your videos and I will always return for more!

@tubastuff 3 месяца назад

Thanks for the detail, Clive. I have one of those solar street lights with LiFePO₄ cells in it that's been running for years. It's surprising to see that it will occasionally respond to insects or bats chasing them, strong winds, especially when accompanied by rain. Fortunately, the thing has a "full on" time of about 30 seconds, so it's not really an issue.

@thepagan5432 3 месяца назад

Really fascinating subject matter, I understand the principles of the build, but would not attempt to build it myself. I've e purchased plans to build a Bluetooth speaker with 10 watt speakers. I bought all the components and have started to build. You are a bad influence on some people Clive as this is the fourth project that I've begun since I started watching you years ago. Believe me when I say it is not just electronic projects but all kinds that stop the decay of the grey matter. Good post, thank you👍

@terryhayward7905 3 месяца назад

I have a complaint, you didn't put a link to tell us where to buy one of these this time. I believe that the "doppler" works in a similar way to a theramin, moving close to it will change the frequency of the oscillator and the change is detected by the first op-amp. ( I could be wrong, but that is how it looks to me )

@smalcolmbrown 3 месяца назад

Thanks :) 8:32 is an economy version of a twin T filter in the negative feedback loop of the first opamp. So the first opamp is a narrow pass filter. I shudder to thing what the bandwidth is More gain less bandwidth and all that

@Jack_Ratchet 3 месяца назад

Wow and Wow! Yo Da Man! I'm going to have to watch this many times to even begin to get an idea of a grasp on this black art. So Interesting

@rowanjones3476 3 месяца назад

‘Trigged’ on the scope… is that like triggered with extra trigonometric math? There’s even spare characters 😂

@mauanderuk 3 месяца назад

You need a few jewels on the glove, hope your hand is healing.

@d.t.4523 3 месяца назад

Thank you, keep working.

@TimoNoko 3 месяца назад

The Dobbler Radar circuitry is very interesting. Some half century ago I tried to build emergency morse radio for standard SOS-frequency, now defunct. Suitable transistors were quite expensive, I recall.

@mattmoreira210 3 месяца назад

8:07 looks like that 150 Ohm resistor serves double duty as both a shunt and as a means for setting the DC bias for the transistor. The capacitors across it serve as bypass to ground for the RF. Anyway, the designers seem to be interested only on the average current across the "shunt", thus the 1st order low-pass filter formed by the adjacent 1K5 and 47K resistors and capacitor (the 47K resistor would have negligible attenuating effect, and could be omitted with no major impact on performance). In your diagram, there are a few essential microstrip elements missing. I've simulated it as is, and the oscillator performs poorly.

@dosgos 3 месяца назад

Oh this would be an interesting follow up video!

@jp040759 3 месяца назад

Thank you

@mattmoreira210 3 месяца назад

hello world

@sudheerkumar5966 3 месяца назад

Very nice

@starlights50 3 месяца назад

T.y. The remotes.. power reduction feature, I encountered on solar banks for fairy lights The long dim rice lights.. self dimming...

@joehopfield 3 месяца назад

There are plastics that are IR transparent - for all that extra complexity (and need for power), I sure hope radar actually adds something useful... Black magic is also a good place to hide back doors ;-)

@icecreamtruckog3667 3 месяца назад

When an inductor is used for switching on and off, as it switches off it makes a reverse current for a short time and the resistor and capacitor could reduce that effect.

@strehlow 4 месяца назад

I'm having trouble undering how the RF section at 7:14 will oscillate. I don't see a feedback path back to the base of the transistor. Could it be from the physical placement of the tracks which is causing capacitive or inductive coupling to the large pad at the base?

@bigclivedotcom 4 месяца назад

It's hard to say when working in such high frequencies. Everything behaves differently.

@angeldelvax7219 3 месяца назад

At RF EVERY part of the circuit is inductive and capacitive. And they all resonate. Even changing a track width, or placing it 0.1mm closer to another track changes the frequency.

@dcallan812 4 месяца назад

Interesting fault 2x👍 The PCB antenna working are something I never really wanted to know about, (as long as they work). We had microwave antennas for speed trap detection and Im just happy they all worked out the box. It was interesting to see the difference between the UK and USA versions.