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- Опубліковано 27 сер 2024
- Dave shows a potential problem with Super Regenerative Receiver circuits, and looks at the issue of interference with his LED light remote control mains switches.
Some fun with two spectrum analysers, a scope, a H-Field probe, and yes, of course a teardown.
The Tekbox EMC near field probes: amzn.to/1Ma20zh
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Ah super-regens, one of my pet subjects! They always have had this problem of radiated crap because the detector is going in and out of oscillation at some supersonic frequency- often around 50-100khz hence the broadband nature of the noise radiated. It consists mostly of sidebands of the quench frequency. You can't screen it or you will stop it working as a receiver! But you can add an RF stage, which will isolate the detector from the antenna and also increase the sensitivity a bit. But they aren't gonna do that in an article that costs just a few bucks. Some people might remember the real cheapie one-hung-lo 27MHz walkie talkies you used to be able to get, they had super-regens in them and made all kinds of strange noises if you brought them close together, due to the same phenomena. They had other problems too, like you could shout further than these things could reach, but that's another topic!
Alan Cordwell Oh wow, yes, I remember those Tandy/Radio Shack walkie talkies doing that! 1970's that was.... Playing sword fights with the antennas making them make weird noises.
Marketed for how many transistors they had!
Alan Cordwell I had these as a young pup, eventually got some Realistic FM 2ways and became the coolest kids in the street. I think they were the first thing I tore down to attempt to make a wireless horror mask speaker to scare my brother. Classic.
Alan Cordwell Statement is basically correct but not precise, all what you wrote about that is only correct for super-regenerative receiver with loop antenna in other cases is not.
The old X10 home automation modules from the 90's and early 2000's had a similar problem. Sometimes the remote wasn't turning the modules on/off depending on their location. Now it all makes sense. wow
Could you do a fundamentals friday about frequency multiplication and/or division or general RF? Imho, the whole RF (and so on) stuff is pretty much voodoo for many hobbyists^^
***** I agree a fundamentals friday about RF components like mixers, multipliers, detectors and such would be awesome!
+1
Lan Party Hosting Vote on that! Maybe some SDR stuff too!
Vote
***** voodoo is easier to understand :(
This channel is like the House MD of electronics, you exclamations are so great, and the content is full of great info. 10/10
As Wikipedia says: "This circuit was widely used in radio receivers, called regenerative receivers, between 1915 and World War II."
Yup, pretty old design ;)
dismayer666
Most radios were no longer using regenerative circuits by 1930. TRF and superheterodyne circuits were easier to use and performed much better.
Having a neighbour that plays with his ham rig also makes these things unusable :)
I hate when #1 isn't working for me either, no matter how hard I push.
I love how I was right about the distance thing, great video dave!
What did they think? How can they ignore that 4 way blocks exist? The case looks like a nice bit of plastic though.
For those new, or unaware of the history there is a chap largely forgotten that invented among other things ''Regeneration'' Edwin Armstrong also invented FM and the superheterodyne receiver and that, to me, ought to make him more famous than he was. He made De Forests Audion work to detect, amplify and transmit, he most likely had a better understanding than De Forest himself. RCA. just as they had done with TV shafted Armstrong over FM good and proper until he jumped from his 13th floor window.
Edit..Oops Forgot to say: great stuff as usual Dave. You are now my very favourite You Tuber.
Ozzie power sockets look so sad. like "oooough"
American sockets look so pissed off like D=
Nukle0n Meanwhile all French sockets are having an erection...
The Danish ones are super happy though
Nukle0n look at the side, it looks mad \ \
___
Nukle0n It's like the mask from Scream.
They look shocked to me like "Oooo!" :0
The scariest thing is you have stuffed your “crawl space” with OneHungLow random/spontaneous deflagration units.
Cheers,
Mark
********************
I have very little problem with the word "regenerative". I have a lot of problems with the word "compartmentalisation".
TheUnnamedGent I have no problems with that one!
EEVblog I think I might be learning to say it now I've typed it out.
TheUnnamedGent thats kinda like how i cant spell short words.... but big long ones i spell just fine. side effect of dyslexia? no idea.
TheUnnamedGent
Just, oh, I don't know. Split the word up into it's individual parts, and take it one one syllable at a time...
You know... compartmentalization
Amazing how it was even certified for sale...a .05 cent high pass (or
even maybe a high and a low pass) filter, a .001 cent random length
antenna, and the thing would work great. Companies should hire quality
engineers like Dave - who know not only how to make something that
works, but with the requisite expertise
to test the prototypes - and the stones to tell the bean counters NO, I
WILL NOT LET YOU CUT THIS CORNER. I completely agree with the other
gentleman, things like this are wrecking HF, even VHF and UHF. Haha,
your neighbor saves 5 dollars on his remote power relay, and you have to
spend $7,500 dollars on filtering, tower, rotor, preamp, digital noise
reduction hardware, and a 5 element cushcraft to be able to make a QSO.
(Or just move and buy a new house!) The governments of the world need to
get it together or one day they will find their satellites and public
safety radios are going to be plagued with constructive and destructive
interference so bad, noise levels so high - they cease to function. Then, without a doubt, someone will spend 5 billion taxpayer dollars to completely revise the satcom
network. Reminds me of the P25 multi-path modulation disaster. Dont get
me wrong, I love new technology - but not when it becomes incompatible
with older, self sufficient infrastructure - in a natural environment
where things fail - it is very dangerous to move forward without looking
back and considering the opportunity cost. I remember once the whole
city's power went out, the noise floor dropped out, and it was 5 watt
10,000 mile 20M QSOs all night off the old 2kw battery bank.
Regen receivers were quite infamous back in the 1920's for interfering with other radios.
you should disable the internal 10dB ATT to lower the DANL by 10dB....and the signal will be much more clear
and the winner of todays,"Geez that was a boring video" award goes to ...
HI Dave,
You commented that the filter cap looked quite good, but of course it wasn't being used as a filter, it was the main component in a transformerless power supply.
A lot of people seem unaware of these very cheap low current supply solutions. A good primer is Microchip's application note; AN954
you got me there on the super regenerative receiver
Really interesting, Dave thanks. I have a couple of these to control some lights in the house and ran into the same problem when they were close together - I had assumed it was the due to the same phase, TIL.
Super-regenerative receiver with loop antenna (and that is what they use and antenna is in same time inductor) are notorious that they create interference for other receivers operating nearby, they even change frequency by moving hand near antenna and there is not many thing that someone can do to fix that issues (shielding is of no use here, only solution is to use RF amplifier that will "isolate" the resonant tank from the antenna but that solution will increase price and is not applicable to when you use loop antenna).
Yes, they intervere each other when close together.. common knowledge, it even says so on the box (here in The Netherlands that is)
I had a gut feeling you were going to explore into the remote issue! Glad you did, thanks for sharing it!
Raise the lumens ( a bit ) over your assistants work bench as reward for making the tool for the tamper-proof screws. Might have seemed like a mundane/lowly task, but we know better! (and...when he screws up...drop the lumens back down!)
The retuning of the receivers may help for range dave, dont forget that the temprature of the room they were setup at will be slightly different to yours, even broardband has its limits.
The remote has a cristal so its accuracy would be different as well at room tempratures, still crappy due to the large multiplication of the cristal.
Interesting to see the measurement quality and speed difference between Tektronix and Rigol.
Superregs should always be shielded and have an RF amp with high reverse isolation (common base) between antenna and detector.
Maybe a project for David2? Building a board that receives the signal with the receiver of one unit, and then decode the signal.
I deal with these all the time, just keep the button pressed, the xmitter away enough to replicate issue and adjust the tuner in the receiver till it works. So far, 100% success rate. (I buy things like this every year during the post xmas liquidation sale.)
I didn't get what you were talking about at first. We call them "odbiornik superreakcyjny" (superreactive receiver) in my country. But I remember having the same problems with it when I used it to control my RC airship (aka. Zeppelin) :)
EDIT: Dave, you have these high speed scopes. You could just see how crappy that noisy waveform (one generated by the receiver) looks like.
With all the knowledge and tools you have, I'm surprised you didn't just build you own remote switching solution. Awesome video however..:-)
i have some kambrook ones. they are fantastic. two of them are right next to each other. no issues at all.
Nice video. I would like to see a properly designed shield so I could see the difference.
dave, they are just FM modulating a counter at 32x the crystal frequency. I did this with a Parallax Propeller chip to broadcast a WAV file to a broadcast FM receiver. Lots of jitter and sideband noise though.
Maybe it is also interesting to show the one-transistor Doppler motion sensor.
EEVblog Haha, that's funny: My remote (of course, with a label that conforms to European standards, telling the battery voltage, and the range to be up to 40m, but not the radio frequency) states the model to be "RC202", or "Type 10164". Also, my set had two sockets that have a dimmer circuit in them, so if you hold the on/off switch, it will dim the light up or down. And yes, that's what all the space on the PCB is for, because the one that I have had open, was one with the dimmer circuit, and it was much more packed. Still, they probably came out of the same factory as yours did (of course with a European/German "Schuko" plug), as the remote and all the design stuff is exactly the same. And I've also had the problem with the screws...
Here they were sold in a discount supermarket chain (by the name of Lidl), so they were actually extra cheap, like 20-25 Euros or something.
.I would be interested to see the IF frequency. I have found most RF interference in receivers enters at the IF section rather than the primary tank circuit.
Would have been fun to see what you can do about it, shield the whole thing (except the antenna)?
Hi Dave, the receiver circuitry is exactly same looking as those 433MHz RF modules currently selling hot at ebay. The 8 pin surface chip is very well a micro, and is probably detecting actual digital messages sent from the different buttons of the transmitter.
Arduino hobbyists are doing these, these days, they are not signal and RF specialists, just putting different messages for different buttons. All digital, no analog. :)
I have a US version of these. I tore one apart and it had a discrete riser board for the receiver, looked very similar to the little receiver boards you can buy on SparkFun and the likes. I found out it was a 315MHz system using the 315MHz and 433MHz receivers I bought there and my scope. Then I traced out the protocol for each button and made a USB interface for it so I can control my lamps from my PC.
Oddly enough I've had three of them on a T-shaped wall tap no more than a few inches apart and they all received just fine. No crystals and no metal shields in them. My PC based transmitter can control lights all the way across the house. I used a technique I learned in your fundamentals friday videos (charge pumping) to boost USB 5V up to 8-9V for more range.
No device shall create harmful interference.
Hi Dave You have two issues to deal with there. Recovering intelligence from a signal is all one thing, Signal to Noise ratio. And noise is a cumulative quantity. Every government agency also specifies the maximum effective radiated power. For unlicensed incidental radiators which is extremely low. If its too high you wind up in trouble with the authorities. Super Regens are known cheap receivers that generate lots of junk. The manufacturer could either build a better receiver to decrease the necessary SNR or increase the transmitter power if it stays with legal limit.
Would that kill the signal from a powerline homeplug ?
I use these a lot! but I use the jackson brand? the dark grey coloured brand from bunnings and they work brilliantly!
We used to use an old portable super-regen radio to 'squeel' other radios.
Get in close, figure out what atation the other guy was listening to, then tune slightly off...big noise!
I used to be really into amateur radio and your teardown explains why every time I would start tuning my stuff it would switch on/off his remote control lights.
I think shielding would not help a lot in this case. There's single transistor circuit, so you don't have reliable antenna separation. Even if you shield the circuit like a nuclear reactor, you will still have non separated antenna, which will 'transmit'.
So, you're saying that if you put two of these in two adjacent sockets, they'll screw each other up? Well done Arlec, well done.
I was hoping he'd put the analyzer antenna next to an unplugged unit and press a button on the remote from across the room, then plug the unit in and do the same and show how the apparent signal from the remote appeared amplified when the unit was plugged in (because of its regeneration).
I have the same problem with a well-known brand in The Netherlands, “ Klik en Klaar”. Receivers 2 meters apart but on the same mains-phase. I could not get it working. Even shielding with alufoil of one of them still failed. So I think the disturbance signal is also transmitted via the mains.
I now have one of the receivers plugged in a wall socket close to the transmitter and use a mains wire to the location where i had my receiver. Crazy solution but it works.
I always think those Australian mainstream sockets look sad about something...
powerline adapters for networking over the power network cause similar problems to sw/hf radios, loads of interference.
i'm sure you know this, but using a dremmel to cut metal in an electronics lab is a bad idea. doesn't matter much at first, but that can be murderous in the long run. just take it outside.
kght222 I don't have an "outside". And that's the first time I've ever done it, two seconds work.
EEVblog fair, and as i said, i'm sure you knew it wasn't the greatest idea. i also pointed out that it is an accumulative thing. i apologize if i sound like an ass.
kght222 It's a fair assertion -- that metal dust gets everywhere. I like (if I have a partner to hold it) to use a small vacuum to catch the sparks directly as they fly off to reduce the amount that gets airborne.
kght222 You should see where I work. People grinding carbon fiber all around sensitive electronics.
I can't wait to see what happens when its all powered up.
I wonder if it is a big problem when you use a magnet to catch the iron-parts. Just below the dremel I use this to keep the surroundings a bit cleaner. Plastic dust is also not sooooo nice though...
Did you make an extra space now in your new lab?
Needs a one transistor input amp and short antenna on the rx circuit. Then shield the super regenerative oscillator coils. Problem solved and greatly improved range. Too much bother though. More fun to short it's output then push the remote and watch the relay go BAM!
i had a couple of the same remote sockets but of course uk version that can receive the remote signal from my garden roughly 40m away from where they are plugged in and no interference between both . i paid about £10
If you were to shield it, would you also be shielding out the signal from the transmitter that you want it to receive? If it can't get out, it can't get in?
Those recievers radiate as part of the reception method. Same with cheap 433.92 cheap car alarmas. The cheapo receiver at 60 cents, is super regenerative. When two of them are close, since they ouput a tone as part of the process, you have a degrade performance
EEVblog , how would you shield a tank circuit? Wouldn't that also block it from receiving the intended signal?
I thought these would emit some kind of intermediate frequency; that would obviously require a more costly circuit though.
If you used a 200Mhz Scope, maybe the sinus-form is just due to the Lowpass in the input and in reallity there was a square?
Did you try putting in your own shielding? Maybe some tin foil or whatever? Not sure if it would work, just curious.
joshcryer That would be interesting to see a DIY shielding video on these
joshcryer That's a slippery slope I didn't really want to go down. As was further details and measurements etc.
joshcryer shielding would not work on this design as the noise is on the receiving antenna (coil) ?
airwood99 Plopped some aluminum foil on my NES which was showing bad banding in the video, something around the video output was putting off some nasty interference. Sometimes it "just works." :) No idea in this case.
joshcryer
But your NES doesn't need to receive RF signals. If you foiled that coil, you'd foil the antenna. No interference, but that would also prohibit receiving.
If you had separate antenna, then you could have it outside the shield.
Last time I used a spectrum analyzer, we had to move the "signal" top near to the top of the screen. The internal gain circuit got adjusted by the max value of the screen, and the noise seen at the bottom was all internal input circuit noise (when using 20dB/div). Maybe you could get a better "signal" view if you lower your reference?
It's baffling that we still don't have a worldwide power plug standard yet. Got pretty much all computer and charging ports standardized except power plugs. smh
Did you know you can get 4-way remote powerboards from Bunnings? They cost around $50 and would've saved you this headache.
How would you go about designing shielding for one of these, without also blocking the incoming signal?
Alistair Buxton
Sadly, you don't. You can tune them more accurately to emit less interference, but that's as far as you'l get.
Dave, correct me if I'm wrong but how can you shield a receiver and it still work?
You would still have to unshielded the antenna which is where the signal is being emitted from.
So how can you shield it?
Would it be any better if you rotate them 90° by X or Y axis? I have always been told that SupReGen receivers interfere because when one receives the LC circuit "locks" onto some frequency, causing it to also transmit at roughly that frequency, causing the other receiver nearby to also receive that, going into the same cycle, and now you have three frequencies that compete for the "lock" on two LC circuits. Never thought about how much truth is in there, and even more unsure how you could measure something like that.
Since this could potentially interfere with near by devices, I wonder how it got past the FCC equivalent of OZ
EEVblog However, there seems to be a difference between the thingys I have and yours: When I plug mine in, it flashes the LED and states to be ready to accept channel programming. I then have to press on or off on the transmitter to set it to the channel I want it. Changing channels between the two modules that are so close to each other didn't do anything though. Still, I wondered that your plugs didn't do that when you first plugged them in, so they are hard wired to a channel? That's a difference then (but only a small one). Still, I don't have nearly the electronics knowledge that you have, so I won't be able to test anything with them (I don't even have a scope, nor would I know how to use one if I had one, LOL).
I don't think these would ever pass FCC certification
I was wondering can you shield the outside plastic case with aluminum or copper tape and get away with that. Curious to know. Hmm
get a zwave remote and some zwave outlet switches. Can get an networked controller for remote UI based switching as well. Teardown of z-wave devices for quality/construction could be another video series. the less crap in the air the better in your case.
8:29 A 3 dB increase of noise floor at least mate!
Dave I have the Aldi brand ones and they worked find for about a year then started to have trouble with channel 2, it would turn on ok but to turn it off I have to go close to it. I have 3 side by side, channel 2,3,4 have no troubles with any other channel just 2. I will rip it apart one day and sort it out.
Could we somehow extend the antenna and put a piece of foil over the oscillator?
can that solve the problem?
Dave l fitted a tunned antenna to transmitter & receiver, dosent look good but improved performance.
Catch Ya Triggy
Bought some of these recently from ASDA (in the UK) and they're crap! 3 of the 4 just about worked (but even less reliably when used at the same time, as you've discovered) and the other just arc'd and fizzled. Looked inside and the leads hadn't been trimmed! Don't feel happy leaving them plugged in.
I had some sockets like this and later got rid of them, because they would switch on and off by themselves at random.
Arlec quality at it's finest
I would install some RF chokes along the circuit
This cheap hung low shit is what's destroying ham radio :(
***** whait... seriously?!? (I'm not that into RF so I have no clue).
We use super expensive sensitive radio gear to pick up a signal in some cases a few watts across the globe.. Hung low splatter crap smashes the bands
*****
sounds frustrating and it doesn't seem like it's going to get better any time soon.
Plasma TV's are bad & cheap ass unfiltered power supplies
+Maximilian Mustermann (“Interprete”) crappy mobile phone signal boosters can actually cause interference spikes and the more powerful ones can actually block cellphones in a whole part of the town.
Resonant tank circuit. One is acting as an antenna trap
Does wraping them in aluminim foil change anything ?
I assume Australia doesn't have anything similar to CE mark or FCC mark?
Carl Fürstenberg Currently, I'm pissed of a USB charger, that emits so much noise, that the touchscreen of attached tablet has awfully lot ghost touches. I can't even unlock the screen. And yes, it has the CE mark :( .
It's from a quite large retail store, but it's one of the cheepo rebranded ones. Now, I want to add ferrite bead to the cable, hoping it helps.
My point is, that even CE mark and purchase from a quite large store don't protect you from crap devices.
Does the CE mark really mean anything anymore? The Chinese are quite happy to print fake CE marks on their electronic items.
acma ctick
ForViewingOnly aren't there any controls?
Maximilian Mustermann There are controls, but the UK/European markets are flooded with fake electrical/electronic goods. I don't think the controlling bodies can keep up with it. All you can do is buy from a large reputable retailer, hoping that they've done their work in checking the source of these goods. But even Amazon are storing and shipping fakes on behalf of other sellers with their "Fulfilled by Amazon" system. Amazon say they will destroy a seller's stock of items if they are found to be fakes, but it still goes on... I've seen a number of batteries and chargers 'Fulfilled by Amazon' that have been removed from Amazon pending investigation... but probably after thousands have already been sold.
Is this the same as a superheterodyne circuit?
Dennis Hill No.
Thanks for that. I got a similar unit and the relay contact got stuck on after a few weeks of use. Changed relay and it did again. The load switched is not terrible inductive I thought. Just the workbench gear, like soldering iron, Some power packs, desk lights etc. Only a few hundred Watts at the best.
Any good idea how to improve this?
Don't know, but is it really a good idea to plug a big metal antenna directly into the SA input? ESD or unintentional contact with a live wire and the first mixer goes byebye. Near field probes and antennas used with SAs are usually isolated for that reason. IMO, an isolated wire is a much better thing to plug into SA if no real probes are available. AFAIK, your SAs are AC coupled, which gives some protection, but I think it's a bad idea nevertheless
Is the antenna position the reason the one on the right works more often than the one on the left? Can you shield the left wall of the enclosure? Will it blend? :D
12:14 KSP - Kerbal Space Program transistor
I would like to know how public utility companies can know & read which electric appliance brands you have plugged in the wall, & if they feed your private household information to the pigs
That MDO3104 is one expensive piece of equipment!
I have 4 of these working in my flat (similar ones anyway)
I love them and wouldn't mind seeing a video of the signal breakdown and just what the coding looks like. I only have a Vellerman 60MHz PC scope so I can't really do it myself.
The thing that bugs me is that sometimes the relay sticks either open or closed, the circuit responds correctly but power either fails to go off or fails to come on. Going from on to off to on a couple of times has always been the cure, I'll need to replace the relay soon.
My tx uses an A12 mini 12 volt battery.
It's great to wake up and click the Computer system has power along with various other things attached.
Click, the Fan comes on if it's hot enough
Really lazy life huh?
dave, is the calculator at 4.17 any good? i have the same one in perfect condition.
"Drift like there is no tomorrow" :D :D :D totally lost on this one :D
I seriously doubt those jokes would pass FCC part 90 requirements.
"Super Regenerative Receiver"
Not such a tongue twister in "General American". :p
accent does it
Yup. Interesting that tongue twisters can exist or not depending solely on accent/dialect; I had never considered that before I saw this vid.
Just purely from curiosity, how hard would it be to mod the receiver unit(s) to have an antenna and/or shielding?
Tzisorey Tigerwuf That's a slippery slope of experimentation I didn't want to go down.
I'll take that to mean "Very"
What if you added a small length of antenna around the inside of the Rcvr case??
Would that help ??
I use X10 modules for switching but I'm on 60Hz 120VAC.
Not sure if they work on 50Hz 220VAC.
16:12 BTW you can't wake up the fish by tapping on the screen... ;)
Australian sockets look like a smiley which had an accident,
And in the U.S. the 70cm band goes from 420MHz to 450Mhz. So this little device falls right in the band.
kd1s therefore in your country the ISM is based within 902Mhz up to 928Mhz (region 2) while many other countries (including europe and australia;) have the ISM band within 433.05Mhz up to 434.79Mhz but they now switching over to 863Mhz up to 870MHz (SRD-Band Europa) due to problems with the 70cm radio CB stuff;)
TubiCal Yeah I know. A lot of the little RF stuff sold here in the U.S. is right smack in the 70cm band. I also have a TI MSP430 watch and I had to give them a copy of my amateur radio license to get it.
Need a single transmit and receiver solution with 10 channels then it would work better. Cost more but you could make your own system using R/C Hobby parts I bet.
did you try changing the baterys ?
Hmm... These don't have to comply with FCC or such standard to be sale-worthy?
RealationGames he's in australia.
CaffeinePizza Thus the "such standard" remark.
Hey Dave, could you do a followup how one should design such a smart plug device and remote, now that we know how not to do it. I thought about that too some time ago when you teared down a fake Apple USB charger. I would love to have Dave approved devices in my home :)