Paramedic student here. About the ECG, the reason you have a lot of garbage when you touch the screen is actually called an artefact, wich is made by you contracting your muscles (easy to see at 24:42), not the screen itself. Contracting muscles = so many polarisation/depolarisation in your nerves (long story short). Right after that when you cleaned it, it was a good readable sinusal rythm (Congrats!)
was wondering about this...couldn't see how electrical activity from other muscles besides the heart wouldn't interfere with the signal - apparently they do! Although 2 years later figured I'd ask: what are the proper steps for maximum signal integrity? Remaining still as possible I'd assume. What about shielding and the like?
The reason for the copper strip-line inductor in the radio-sonde is to achieve high Q in the LC circuit. It would be for frequency stability as it is just an LC oscillator without a crystal to keep the transmit frequency stable. I remember I came across a similar unit in the 80ies and they used clever techniques to send the temperature, humidity and the pressure using purely analogue modulation schemes. I think they used the the transmit frequency to communicate the temperature. In that case maybe the temperature-contraction of the copper strip-line as it got colder would be enough to change the frequency (colder = higher freq.)
Soo, I was casting this to my chromecast in the morning and then left it on pause. My phone leaves the casted video thumbnail as a lock screen image. On the coffee break I needed to show a pic to my coworkers. So I open my phone and looky who's there! Shirtless Dave Jones fullscreen :D Got a few surprised looks. Oh well..
Vaisala also had spinoff - Vaisala Technologies Inc. (VTI) - that still produce (I hope) top tier accelerometers, last time I heard about them their biggest gripe were that they produced too high quality and find a reasonable way to get consumer level product line to be competetive in consumer market. Most of the western cars had atleast one of their sensors about ten years ago.
Nothing bad. Consumer products are flimsy compared what they did, but the application base is wider and so is the volumes. They were just balling the idea and felt (jokingly of course) that it is hard task to produce a quality that by their quality standars ends up to trashcans. Accelerometers were just surfacing to consumer products (Nindendo Wii and smartphones etc.) in large scale back then.
About the radiosonde, my dad bought a couple of radiosondes from a surplus store. They were probably late 1950's early 1960's vintage. As a kid I was really intrigued by them. Like the one you have there were three sensors (I expect now they would have GPS sensors). There was one each for temperature, humidity and atmospheric pressure. Note that the sensors were all mechanical. The barometer was an aneroid (I think that thing you showed in the inset, that you said was a humidity sensor is actually an aneroid barometer cell). The humidity sensor was a bunch of horse hairs (or something like it) and the thermometer was bi-metal (as was/is used in electro-mechanical thermostats). The "analog to digital converter" was really something. There was a disk (like a vinyl record) with several tracks. If I remember right the tracks only went around about a third of the circumference. Then there were three styluses spaced 120 degrees apart around the disk so that only one would touch the tracks at a time. On the opposite end of each playback arm (with a fulcrum between) a respective sensor was connected. Included with the radiosonde was a conversion chart. The spinning disk with styluses would generate Morse code. The chart listed what the code translated to in temperature, relative humidity and atmospheric pressure.
TheSkogemann without any medical background (does getting an A* in IGCSS biology 1 year ago count?), I can clearly see peaks whenever he stresses his voice!
That's what i ment - you are not supposed to talk when taking the ECG. I don't have any medical background, but i have taken many ECG's and EEG's before. The nurses often freaked out at me as a kid if i moved the slightest or talked. (Aged 6-10) :D I believe that some of the modern technology can filter out muscle activity, but i am not sure.
Nope, you can do ECG on Ergometer and even when walking/running normally. But that requires real equipment with shielded electrodes for example. The nurse wants you to be quiet because the diagnostic ECG is supposed to be made at rest condition.
@Jorg Fischer Shielded electrodes won't do anything if the patient is moving. The interference is not from EMI or capacitive coupling. It is from muscle that exhibits a signal larger in magnitude than cardiac muscle due to size and proximity (the electric signal of the heart muscle is attenuated before it reaches the electrode because it has to go through pericardium, lung, and skeletal muscle). You can get a usable ECG signal by reducing the bandwidth and increasing the rejection done by the filters. These things will result in signal distortion and may actually remove physiologic information from the ECG signal. The reason this is okay is because doctors aren't concerned about the information that is removed or distorted when it doesn't apply to what they are looking for. It can be, however, detrimental to remove/distort such information if you are using an ECG to clarify an arrhythmia or to be very sensitive in determining ischemia.
Dave, the majority of the noise on your ECG is muscle noise, you need to relax completely when taking an ECG trace. The waveforms shown there are actually really good!
That copper RF stripline section is a very high-Q tuned folded resonant cavity. You can see the RF transistor coupling at one end of it, the tuning cap to case ground (tiny capacitances are required to tune it) and the end-plate capacitance to feed the antenna. Purpose is to match the output impedances as well as provide sharp filtering (which becomes quite a problem at the frequencies involved if you want high unloaded Q factors) Unlike cellphones and other mass-produced equipment the radiosonde will require a frequency not covered by off-the-shelf filters and being single-use cost is also a factor. Resonant cavity filters are also used for sharp filtering at transmission sites to prevent interference by co-located antennae and transceiver systems that would otherwise need to geographically well spaced to prevent desentitization of receivers being operated at the same time as transmitters. They can be set to reject or accept particular frequencies and are often applied in banks to obtain sufficient filtering. Their high-Q factor means losses are minimised and selectivity is maximised.
if you stick the ECG electrodes in both your ears and one up your nose then it turns it into a EEG, the 3v coin cell should be swapped for 400v 3 phase in this application.........oh, and the turf??......wow!!
At 37:00 This is a power oscillator and the freq will vary due to the ambient teperature, thus a temp sensor and by measuring the receiver carrier freq you can get the temp info. Also an oscillator only circuit reduces the complexity and makes the supply current to rf power conversion a lot more efficient as back then UHF generation was not trival and the battery needs to be small and lightweight. Also this circuit nees to work down to -100C!. Gary -RF Engineer.
Wanted to comment on the LabGruppen part (first pronunciation in the video was the correct one ;). They are in fact one of the most renowned manufacturers of professional audio amplifiers and are quite expensive. This C-series is meant as a 'permanent' installation amplifier, instead of their touring amplifiers which are more ruggedised for use 'on the road'. The designs in a lot of their amplifiers are similar and indeed date back to the early nineties. When you go to a large concert there's actually a reasonable chance that they are using LabGruppen amplifiers for the PA system. I believe they have majorly contributed to making lightweight class-D type amplifiers popular for professional live sound applications.
The special connectors on the ecg leads were brought in specifically to replace the 2mm exposed pins that they used to use. Apparently there had been accidents where old stile ecg leads had be inserted in to IEC power outlets which did not turn out to well for the person hooked up to the other end. Any equipment that still used the old 2mm and also 4mm exposed bennana plugs had to be retro fitted with the new connectors. In some cases it was simply changing the connectors on the pannel. In other cases whole replacement enclosures were required. In very rare instances the product was replaced as it was not cost effective to replace the connectors.
If you keep any of your muscles tense (arm muscles holding anything), the brain sends a pulse train that will show up all over the place and mess the ECG readings.
Hi Dave, I was hunting the RS-80 Radio-Sonde here in Germany. Was really great fun. We hat a 403 MHz receiver with a Yagi-Antenna. And we sometimes got these cute device. Our "German" devices where on 403 MHz that had a solder-jumper-settable PLL-Circuit inside for the transmitter frequency. The outer Sensor was Temp and Humidity. The big tin can inside is a capacitive pressure sensor. And there was an additional stripped-down GPS-Receiver glued to outside of the the RS-80. It only measured the different GPS-doppler-shifts from the satellites which then were transmitted as 9K6-RS232 with the downlink. The Main-downlink consisted of about 6 tones (each about 300 ms long) which represented either a reference-frequency or one of the measured parameters (Temp, Humidity, Pressure). It actually sounded like a badly tuned old fashioned Synthesizer-Keyboard :-) .At this time the balloons where already started automatically. The battery was an open and really dry stack of two different metals and something like cloth. When the sonde needed to be activated before launch some water or acid was injected into the battery which initiated the generation of electricity and started the sonde. A am sure that your device is not a 403 MHz device - but something like 2 GHz because the Antenna is a 1/4-Lambda-Groundplane and it is far to small for 430 MHz.
Yes, they are relatively standard EKG connectors, the "banana" sockets. We used them on some EEG systems. Also, the EKG board might have a 60Hz filter, not the 50Hz for Aussie-land. The *low* pass filter doesn't look like its optimized either.
There is a 50Hz notch filter on-board that rejects about 20dB given component tolerances as measured on the bench. What do you mean by optimize? Please elaborate. If you try decreasing the cut-off filter's corner frequency or changing the response to something like a chebyshev you will distort the QRS complex which can lead to misdiagnosis. If you want to increase the order then you will increase the gain error as well as will increase the space/cost/current requirements.
Oops. I meant low-pass filter. Not high-pass. There is a tendency for A/D to get overwhelmed if the sample rate is too low, and the A/D range is not sufficient for the noise. Disclaimer: I worked on EEG systems, not EKG, so I maybe mistaken.
Dave, was trying to put my finger on the excitement felt watching your 'Mail Bag' vids. Eureka! it's like CHRISTMAS, every time. Thanks, I'm sure I speak for us all, wonderful stuff.
Radiosondes will last up to several hours depending on how long the balloon stays up. Visalia charged a fortune for the ground unit to receive the 400mhz version. Then NWS in the USA uses a 1.6ghz version. I have personally launched serval they typical use a activated water battery that you soak before launch. New ones use GPS the old ones either didn't give you wind dir and speed or they used a radio Theodolites hence the 1.6ghz of the NWS. I was born in 81 so the only thing i can think maybe something that may change the coupling the with temp. Would you like a modern one??? I can send one if so.
If I'm not mistaken, it's to prevent ground loops. So it is seen a lot in analog circuits. Basically everything gets its own private line straight to ground, so some components don't develop a different ground potential. I agree with the Fundamental Friday idea. Though I kinda want to see a generic "Best PCB layout practices" episode.
Dave, this amp board is really two tracking buck regulators powering a 'normal' output stage. Those MOSFET's and diodes are the components for the buck stages. Schematics can be found on the web. Stunning amp anyhow. (have repaired some of those long ago)
It seem that amplifier is something they call "class TD". I imagine the mosfets/diodes/inductors in the middle is two buck converters one for each rail, with the voltages tracking the output to limit the dissipation in the regular class-B output with the NPNs/PNPs
The radiosonde will have a water activated battery, one that doesn't contain any harmful stuff (heavy metals etc), as these things generally plop down in the sea. Mikeselectricstuff did a teardown of a much newer one.
Dave, your so-called penetrators on the Radiosond are in fact feedthrough capacitors. They were often used to feed low voltage power through metal enclosures containing high frequency circuitry and also feeding out the results that the HF circuitry produced. This prevented radio frequencies from escaping the enclosure.
hahaha I've see inside of enough Lab Gruppen amps to know that layout as soon as I saw it! I am no pixie wrangler like you Dave. I am an ex live audio tech. I used to work for the largest audio company in Australia. Lab Gruppen is the bees knees in the live audio industry. The best high power, switchmode amps, built tough enough to handle being pulled in and out of a truck, and run as hard as they can night after night! The models we used where much more powerful.
That was a patient inventory label on that pink TV. When you are in the hospital,they put those on your personal stuff. It wasn't an auction label. Sad to see so many decent camera's ending up as a teardown because they didn't last. I love the fact someone sent you turf. ha ha ha.
The ECG. The noise is called artifact. All ECG systems do this. If you lay still and stopped moving the device around, you will get a much better result. even while you were dancing, I can see all the relavent signals required to parform diagnostics. A time pulse would be good in order to calculate/confirm timings. The signals are looked at from an amplitude and from a timebase point of view. An earthed farriday cage would also help.
That amplifier is actually a very modern design. It is class TD. It uses a high efficiency SMPS and a class AB output. But to increase efficiency they add a buck converter(the power diodes and mosfets you show) between the PSU and AMP which monitors the input signal and provides just enough voltage to the class AB amp to avoid clipping. With so little difference between the active voltage rails, and the voltage of the signal being reproduced, you get a very high efficiency.
Casio CFX-9850GB PLUS: 9.000000007 Casio fx-991MS: 8.999998637 Casio fx-991ES: 9.000000007 hp 50g: 8.99999864267 So basically the same as mentioned here: www.rskey.org/~mwsebastian/miscprj/models.htm
That Vaisala thingy is and analog temp/air pressure+humidity measurement/rf transmit system and it's used on weather reseach, those units were attached to huge gas balloons and released at regular intervalls.
For the calculator, could the 'chipset' just be a bog standard (knock off) mirco ? The need for aaa as apposed to a coin cell might suggest the power consumption is a little higher
That model radiosonde sends PTU, pressure, temp, humidity. It's carried by a hydrogen balloon (in australia) and tracked by C-Band windfind radar which allows calculation of the wind and elevation. 403 Mhz is pretty much bang on for TX freq The battery pack in these were an open cell battery that was hydrated(dropped in a bucket) before launch which generates enough heat during the flight to keep the electronics alive. Transmit time was slightly variable(90+ min), but they track out to approx 110 km, depending on radar power and when the balloon actually bursts New radiosonde has standard AA batteries, with two small water reservoirs for thermal mass.They also transmit raw gps back to the ground station for wind calculations which allows the radar to stay in weatherwatch mode. I'll see if I can get my hands on one of the new types to send in.
I recall seeing plenty of strip line inductors and coupling sections in rigs published in ARRL (American Radio Relay league) books since the early 70s. This was a very common technique when building higher VHF and UHF amateur equipment.
Great mailbag. Could you review those SwissMicros calculators (based on HP design) you showed in the "quick mailbag" video? I'm thinking of buying but there is no good review around yet.
I have a Casio FX-82ES and I get 9.000000007 with that formula at 18:55 in the video. Interesting way to spot the chipset though. Never heard of it before.
An Australian who burns in the sun? Are you sure you're not a secret Canadian? :-) On an unrelated note: any chance of a video about South Australia's "we don't need electricity all the time, do we mates?" approach to power generation? :-)
I had one of those TVs, got it at a second-hand market, it was white not pink. I thought it was neat. It had a selector for VHF/UHF, but as it must have been specified for the UK, it didn't have a switch behind it.
I love those old portable TVs, I see them in thrift stores all the time but sadly they are near useless now because there are no analog stations any longer and most don't have any sort of external input, so I always pass on them, as much as I love the look of them.
Hi Dave, you teardown radioson RS80 reminded me that I had one in the shed, I collected it in about 2005 on one of my trips across the to the west from the BOM site at Ceduna on the WA/SA boarder, the blokes there love to have a chat and I spent 2 days there, the devices are all tested before they are loaded into the automatic deployment machine, it is worth a whole show just on that topic, but if you want I can send this one to you to compare, but they are made standard across the world, so changing them would be a big can of worms..
still want one, not the bute one, but similar,because never had one as they were sold here. Saw several on our craigslist analog page, but they were in some kind retro electronics shops and they cost multiple tens of euros for some reason. In unknown condition and analog tv is dead even.
You should check the interference of the ecg project against devices that are not in the same loop as the ecg. You're closing a loop between the test leads the oscilloscope and your hand arm sensors etc etc..
EKG: Noise is normal for any movement. even med grade hardware has it unless filtering is applied (built into monitors). the colour codes are standard pretty much, those are the north american (AHA) ones. "White's on the right and Smoke over Fire" given its only got red and white, that's going to give you lead II
Ha!! The Batteroo never even raised his heart-beat even 1 BPM!! Enough's enough Betteroo - when will you guys just go away? Talk about flogging a dead horse..
37:09 - my experience is very limited, and peripheral -- I was around when some other folks were working on a project for a balloon launch, and played a few minor roles in the project. That said, I can say that temperature was _very much_ a concern for things. We tested our build, for example, in liquid nitrogen... there's a write-up on it here: www.instructables.com/id/Thermal-test-chamber-for-edge-of-space-testing.-D/ ... not sure if that gives you any useful data, but it's about all I know. :)
The amp is probably class H. The two MOSFETs will be switching rail voltages between low and high voltages depending on what the signal is doing. The diodes are likely commutation diodes. Sanken are well known for making Audio power transistors - their primary speciality is being highly linear, but with plenty of power handling and high speed. 60MHz fT for power transistor's isnt that common.
A few years ago I saw a really good ripoff of a Casio FX series at a dollar store. I wish I had bought it. It was about 99% identical to a real Casio including an FX model number but no branding anywhere on it.
Ahh UHF... The movie that nobody remembers at all sadly.. It did (sort of) launch the careers of the guy who played Kramer on Seinfeld. And of course one Fran Dresher.. :) Miss Fine!!!!!!
Maybe the air dialectic capacitors shifted the output frequency dependent on barometric pressure, making the carrier an additional analogue telemetry.channel.
Not fan of the idea of using that function to test calculators. it's biased towards a specific processor and brand. something to consider is that you are giving cos a tiny and insignificant value (angle) from sin. As such, you might want to invert the order for asin/acos and sin/cos so that you feed an actual workable angle to cos. Doing so on my old Casio gives me the perfect 9 you're looking for.
Anything pink should be forwarded to Big Clive.
Very true lol.
Now i'm definitely not watching this video at work
I don't think that item would fit into... uhm... well...
100% This.
They don't call him big for nothing.
Paramedic student here. About the ECG, the reason you have a lot of garbage when you touch the screen is actually called an artefact, wich is made by you contracting your muscles (easy to see at 24:42), not the screen itself. Contracting muscles = so many polarisation/depolarisation in your nerves (long story short). Right after that when you cleaned it, it was a good readable sinusal rythm (Congrats!)
was wondering about this...couldn't see how electrical activity from other muscles besides the heart wouldn't interfere with the signal - apparently they do! Although 2 years later figured I'd ask: what are the proper steps for maximum signal integrity? Remaining still as possible I'd assume. What about shielding and the like?
The reason for the copper strip-line inductor in the radio-sonde is to achieve high Q in the LC circuit. It would be for frequency stability as it is just an LC oscillator without a crystal to keep the transmit frequency stable.
I remember I came across a similar unit in the 80ies and they used clever techniques to send the temperature, humidity and the pressure using purely analogue modulation schemes.
I think they used the the transmit frequency to communicate the temperature. In that case maybe the temperature-contraction of the copper strip-line as it got colder would be enough to change the frequency (colder = higher freq.)
Makes sense, thanks.
I wonder about arc-over under low pressures. UHF cans needed to be pressurized back in the dark ages
Soo, I was casting this to my chromecast in the morning and then left it on pause. My phone leaves the casted video thumbnail as a lock screen image. On the coffee break I needed to show a pic to my coworkers. So I open my phone and looky who's there! Shirtless Dave Jones fullscreen :D Got a few surprised looks. Oh well..
Petteri Kähärä Ahahahahahahahahahaha!
Ei se väärin oo ;)
Noei jos tykkää :D
The ECG part is at 22:06
"sigh" *unzips*
Patent on measuring small capacitances will be to do with reading a humidity sensor.
Vaisala also had spinoff - Vaisala Technologies Inc. (VTI) - that still produce (I hope) top tier accelerometers, last time I heard about them their biggest gripe were that they produced too high quality and find a reasonable way to get consumer level product line to be competetive in consumer market. Most of the western cars had atleast one of their sensors about ten years ago.
Savupirtti wait why is that bad
Nothing bad. Consumer products are flimsy compared what they did, but the application base is wider and so is the volumes. They were just balling the idea and felt (jokingly of course) that it is hard task to produce a quality that by their quality standars ends up to trashcans. Accelerometers were just surfacing to consumer products (Nindendo Wii and smartphones etc.) in large scale back then.
Any of you guys miss photonicinduction?
What happen to him?
Fennec Fox i really miss him he's randomly gone off the grid
Actually there was a post last month on his discussion forum sayingg he has stuff planned for 2017
nah weve seen him posting about fun in 2017 on his channels discussion page
who doesnt like high voltage vs ftuits veggies and random bits of gear
About the radiosonde, my dad bought a couple of radiosondes from a surplus store. They were probably late 1950's early 1960's vintage. As a kid I was really intrigued by them. Like the one you have there were three sensors (I expect now they would have GPS sensors). There was one each for temperature, humidity and atmospheric pressure. Note that the sensors were all mechanical. The barometer was an aneroid (I think that thing you showed in the inset, that you said was a humidity sensor is actually an aneroid barometer cell). The humidity sensor was a bunch of horse hairs (or something like it) and the thermometer was bi-metal (as was/is used in electro-mechanical thermostats).
The "analog to digital converter" was really something. There was a disk (like a vinyl record) with several tracks. If I remember right the tracks only went around about a third of the circumference. Then there were three styluses spaced 120 degrees apart around the disk so that only one would touch the tracks at a time. On the opposite end of each playback arm (with a fulcrum between) a respective sensor was connected.
Included with the radiosonde was a conversion chart. The spinning disk with styluses would generate Morse code. The chart listed what the code translated to in temperature, relative humidity and atmospheric pressure.
You are supposed to sit totally still and quite when you take an ECG. Muscles and movement will make noise.
Yes, I clearly remember the doctor telling me to stay still. It's not because of that dinky little electronics.
TheSkogemann without any medical background (does getting an A* in IGCSS biology 1 year ago count?), I can clearly see peaks whenever he stresses his voice!
That's what i ment - you are not supposed to talk when taking the ECG. I don't have any medical background, but i have taken many ECG's and EEG's before. The nurses often freaked out at me as a kid if i moved the slightest or talked. (Aged 6-10) :D
I believe that some of the modern technology can filter out muscle activity, but i am not sure.
Nope, you can do ECG on Ergometer and even when walking/running normally. But that requires real equipment with shielded electrodes for example. The nurse wants you to be quiet because the diagnostic ECG is supposed to be made at rest condition.
@Jorg Fischer Shielded electrodes won't do anything if the patient is moving. The interference is not from EMI or capacitive coupling. It is from muscle that exhibits a signal larger in magnitude than cardiac muscle due to size and proximity (the electric signal of the heart muscle is attenuated before it reaches the electrode because it has to go through pericardium, lung, and skeletal muscle). You can get a usable ECG signal by reducing the bandwidth and increasing the rejection done by the filters. These things will result in signal distortion and may actually remove physiologic information from the ECG signal. The reason this is okay is because doctors aren't concerned about the information that is removed or distorted when it doesn't apply to what they are looking for. It can be, however, detrimental to remove/distort such information if you are using an ECG to clarify an arrhythmia or to be very sensitive in determining ischemia.
They are standard connectors for ECG and EEG.
Blooper @ 7:55
It doesn't happen very often that your professional made videos contain lil bloopers like these :)
Gotta love your mailbag Dave!
EEVblog, The sensor is temperature and humidity. I am a meteorologist in the US Navy and I used these a lot.
Thanks.
And obviously, the clip holds a barometric pressure sensor (a diaphragm type I presume)
Vaisala these days runs the weather warning system (or something) of US these days IIRC.
Dave, the majority of the noise on your ECG is muscle noise, you need to relax completely when taking an ECG trace. The waveforms shown there are actually really good!
That copper RF stripline section is a very high-Q tuned folded resonant cavity. You can see the RF transistor coupling at one end of it, the tuning cap to case ground (tiny capacitances are required to tune it) and the end-plate capacitance to feed the antenna. Purpose is to match the output impedances as well as provide sharp filtering (which becomes quite a problem at the frequencies involved if you want high unloaded Q factors)
Unlike cellphones and other mass-produced equipment the radiosonde will require a frequency not covered by off-the-shelf filters and being single-use cost is also a factor.
Resonant cavity filters are also used for sharp filtering at transmission sites to prevent interference by co-located antennae and transceiver systems that would otherwise need to geographically well spaced to prevent desentitization of receivers being operated at the same time as transmitters. They can be set to reject or accept particular frequencies and are often applied in banks to obtain sufficient filtering. Their high-Q factor means losses are minimised and selectivity is maximised.
The sensor strip on the Radiosonde is both humidity and temperature. The sensor capsule that goes in the clip is a barometric sensor, not humidity.
I thought it looked like a diaphragm pressure sensor rather than something that measures humidity.
Nice sinus rhythm! Dave's SA node is firing beautifully!
Can you hook up the ECG to the Princess TV?
if you stick the ECG electrodes in both your ears and one up your nose then it turns it into a EEG, the 3v coin cell should be swapped for 400v 3 phase in this application.........oh, and the turf??......wow!!
At 37:00 This is a power oscillator and the freq will vary due to the ambient teperature, thus a temp sensor and by measuring the receiver carrier freq you can get the temp info. Also an oscillator only circuit reduces the complexity and makes the supply current to rf power conversion a lot more efficient as back then UHF generation was not trival and the battery needs to be small and lightweight. Also this circuit nees to work down to -100C!.
Gary -RF Engineer.
Wanted to comment on the LabGruppen part (first pronunciation in the video was the correct one ;). They are in fact one of the most renowned manufacturers of professional audio amplifiers and are quite expensive. This C-series is meant as a 'permanent' installation amplifier, instead of their touring amplifiers which are more ruggedised for use 'on the road'. The designs in a lot of their amplifiers are similar and indeed date back to the early nineties.
When you go to a large concert there's actually a reasonable chance that they are using LabGruppen amplifiers for the PA system. I believe they have majorly contributed to making lightweight class-D type amplifiers popular for professional live sound applications.
The special connectors on the ecg leads were brought in specifically to replace the 2mm exposed pins that they used to use.
Apparently there had been accidents where old stile ecg leads had be inserted in to IEC power outlets which did not turn out to well for the person hooked up to the other end.
Any equipment that still used the old 2mm and also 4mm exposed bennana plugs had to be retro fitted with the new connectors. In some cases it was simply changing the connectors on the pannel. In other cases whole replacement enclosures were required. In very rare instances the product was replaced as it was not cost effective to replace the connectors.
That little pink tv was a prison inmates.
Please don't ask how I know..
yeah, I think so too...
If you keep any of your muscles tense (arm muscles holding anything), the brain sends a pulse train that will show up all over the place and mess the ECG readings.
Great timing half way through watching you open mail I get a new package that comes from eevblog. My first multimeter!
7:45 think you missed some editing there mate
tsk tsk falling asleep at the wheel dave! :P
sebastianblevdet just a glitch in the matrix
get over yourself.
Hi Dave,
I was hunting the RS-80 Radio-Sonde here in Germany. Was really great fun. We hat a 403 MHz receiver with a Yagi-Antenna. And we sometimes got these cute device. Our "German" devices where on 403 MHz that had a solder-jumper-settable PLL-Circuit inside for the transmitter frequency. The outer Sensor was Temp and Humidity. The big tin can inside is a capacitive pressure sensor. And there was an additional stripped-down GPS-Receiver glued to outside of the the RS-80. It only measured the different GPS-doppler-shifts from the satellites which then were transmitted as 9K6-RS232 with the downlink. The Main-downlink consisted of about 6 tones (each about 300 ms long) which represented either a reference-frequency or one of the measured parameters (Temp, Humidity, Pressure). It actually sounded like a badly tuned old fashioned Synthesizer-Keyboard :-) .At this time the balloons where already started automatically. The battery was an open and really dry stack of two different metals and something like cloth. When the sonde needed to be activated before launch some water or acid was injected into the battery which initiated the generation of electricity and started the sonde. A am sure that your device is not a 403 MHz device - but something like 2 GHz because the Antenna is a 1/4-Lambda-Groundplane and it is far to small for 430 MHz.
Yes, they are relatively standard EKG connectors, the "banana" sockets. We used them on some EEG systems.
Also, the EKG board might have a 60Hz filter, not the 50Hz for Aussie-land. The *low* pass filter doesn't look like its optimized either.
There is a 50Hz notch filter on-board that rejects about 20dB given component tolerances as measured on the bench. What do you mean by optimize? Please elaborate. If you try decreasing the cut-off filter's corner frequency or changing the response to something like a chebyshev you will distort the QRS complex which can lead to misdiagnosis. If you want to increase the order then you will increase the gain error as well as will increase the space/cost/current requirements.
Oops. I meant low-pass filter. Not high-pass. There is a tendency for A/D to get overwhelmed if the sample rate is too low, and the A/D range is not sufficient for the noise.
Disclaimer: I worked on EEG systems, not EKG, so I maybe mistaken.
Dave, was trying to put my finger on the excitement felt watching your 'Mail Bag' vids. Eureka! it's like CHRISTMAS, every time. Thanks, I'm sure I speak for us all, wonderful stuff.
Radiosondes will last up to several hours depending on how long the balloon stays up. Visalia charged a fortune for the ground unit to receive the 400mhz version. Then NWS in the USA uses a 1.6ghz version. I have personally launched serval they typical use a activated water battery that you soak before launch. New ones use GPS the old ones either didn't give you wind dir and speed or they used a radio Theodolites hence the 1.6ghz of the NWS. I was born in 81 so the only thing i can think maybe something that may change the coupling the with temp. Would you like a modern one??? I can send one if so.
Don't ask just send it. Or do it yourself and post a video to show us!
How you flipped at 11:08 made me lol.
There are a lot of videos that you mention star-grounding, but I don't remember one explaining why you would use it.
Something for "Fundamental Friday".
Because there is no wire.
If I'm not mistaken, it's to prevent ground loops. So it is seen a lot in analog circuits. Basically everything gets its own private line straight to ground, so some components don't develop a different ground potential.
I agree with the Fundamental Friday idea. Though I kinda want to see a generic "Best PCB layout practices" episode.
Dave, this amp board is really two tracking buck regulators powering a 'normal' output stage. Those MOSFET's and diodes are the components for the buck stages. Schematics can be found on the web. Stunning amp anyhow. (have repaired some of those long ago)
That turf opening was hilarious
It seem that amplifier is something they call "class TD". I imagine the mosfets/diodes/inductors in the middle is two buck converters one for each rail, with the voltages tracking the output to limit the dissipation in the regular class-B output with the NPNs/PNPs
The radiosonde will have a water activated battery, one that doesn't contain any harmful stuff (heavy metals etc), as these things generally plop down in the sea. Mikeselectricstuff did a teardown of a much newer one.
Also a mechanical barometer attached to the silver circle on the bottom. I had a complete one that I took apart to learn how it worked.
Dave, your so-called penetrators on the Radiosond are in fact feedthrough capacitors. They were often used to feed low voltage power through metal enclosures containing high frequency circuitry and also feeding out the results that the HF circuitry produced. This prevented radio frequencies from escaping the enclosure.
That PAP would be great for emulations.
I wouldn't say great
Adequate is probably the correct term.
I guess I'm quite randomly asking but does anyone know a good place to watch new series online ?
@Reid Dorian Flixportal
@Musa King thank you, signed up and it seems to work =) Appreciate it!
WARNING: Contains Partial Frontal Nerdity!
hahaha I've see inside of enough Lab Gruppen amps to know that layout as soon as I saw it! I am no pixie wrangler like you Dave. I am an ex live audio tech. I used to work for the largest audio company in Australia. Lab Gruppen is the bees knees in the live audio industry. The best high power, switchmode amps, built tough enough to handle being pulled in and out of a truck, and run as hard as they can night after night! The models we used where much more powerful.
That was a patient inventory label on that pink TV. When you are in the hospital,they put those on your personal stuff. It wasn't an auction label. Sad to see so many decent camera's ending up as a teardown because they didn't last. I love the fact someone sent you turf. ha ha ha.
Gold @13:44! Love UHF.....
The ECG. The noise is called artifact. All ECG systems do this. If you lay still and stopped moving the device around, you will get a much better result. even while you were dancing, I can see all the relavent signals required to parform diagnostics. A time pulse would be good in order to calculate/confirm timings. The signals are looked at from an amplitude and from a timebase point of view. An earthed farriday cage would also help.
Hi Dave! What are the shelves used in the background, if you don't mind me asking? Thanks.
no worries turf has a form for ordering a free sample. guessing someone's been playing
That amplifier is actually a very modern design. It is class TD. It uses a high efficiency SMPS and a class AB output. But to increase efficiency they add a buck converter(the power diodes and mosfets you show) between the PSU and AMP which monitors the input signal and provides just enough voltage to the class AB amp to avoid clipping. With so little difference between the active voltage rails, and the voltage of the signal being reproduced, you get a very high efficiency.
labgruppen.com/technology/class-td-output-stage
Hey Dave, the Digi-Key crinkled paper packaging is called Geami WrapPak.
Wait, so the rip-off calculator calculates a more exact result than the original?
Based on that one metric, yes.
TI-36X Pro gave 9.000001077... disappointing as it is a TI and just purchased a few months ago. Hope others will list their results.
Casio CFX-9850GB PLUS: 9.000000007
Casio fx-991MS: 8.999998637
Casio fx-991ES: 9.000000007
hp 50g: 8.99999864267
So basically the same as mentioned here: www.rskey.org/~mwsebastian/miscprj/models.htm
Thanks for the link. Interesting stuff although it was last updated 10 years ago!
What is the model/part number of the Tektronix 'scope evaluation kit? You never showed a close-up of the board.
Nice looking amplifier, appears to be class AB with some nice Sanken outputs.
That Vaisala thingy is and analog temp/air pressure+humidity measurement/rf transmit system and it's used on weather reseach, those units were attached to huge gas balloons and released at regular intervalls.
The cylinder is a aneroid which holds a reference pressure to measure altitude. It extends while the balloon ascents.
Yay for UHF! That's my all-time favorite movie.
I think the tabs that you call ground on the radiosonde is actually the quarter wave counterpoise for the 1/4 wave antenna.
For the calculator, could the 'chipset' just be a bog standard (knock off) mirco ? The need for aaa as apposed to a coin cell might suggest the power consumption is a little higher
Maybe they use the NTC for sensing the temperature for high side transistors.
Love the UHF reference, "uh oh, looks like bob o has been eating, Yappies dog treats", "With just a hint of cheese".
I think these big diodes and mosfets are parts of DC/DC converter not audio path.
Hello my name is Dave and welcome to EEVBlog. Today we're going to learn how to make plutonium out of common household items. 😋
Good to see you're still alive!
You know you're doing something right when the knife you use to open a package is bigger than the package its self, lol.
That model radiosonde sends PTU, pressure, temp, humidity. It's carried by a hydrogen balloon (in australia) and tracked by C-Band windfind radar which allows calculation of the wind and elevation.
403 Mhz is pretty much bang on for TX freq
The battery pack in these were an open cell battery that was hydrated(dropped in a bucket) before launch which generates enough heat during the flight to keep the electronics alive. Transmit time was slightly variable(90+ min), but they track out to approx 110 km, depending on radar power and when the balloon actually bursts
New radiosonde has standard AA batteries, with two small water reservoirs for thermal mass.They also transmit raw gps back to the ground station for wind calculations which allows the radar to stay in weatherwatch mode.
I'll see if I can get my hands on one of the new types to send in.
Does scope have high frequency smoothing function?
the radiosonde air dielectric capacitor bit looks like a gamma match type of affair?
I recall seeing plenty of strip line inductors and coupling sections in rigs published in ARRL (American Radio Relay league) books since the early 70s. This was a very common technique when building higher VHF and UHF amateur equipment.
I wonder how much less noisy that ECG would have been if they isolated the output to the scope.
Great mailbag. Could you review those SwissMicros calculators (based on HP design) you showed in the "quick mailbag" video? I'm thinking of buying but there is no good review around yet.
Is a batterizer similar to a Joule thief?
"It is actually turf? That's a first. I've been sent turf to an electronics mailbag. Why? Why have I been sent turf?" -- Dave Jones, 2017.
Dying.
me as well.... Best of this episode...:):) :) :) :)
Just fyi, that is pretty standard regarding the ECG, in that even the best ecg monitoring systems pick up electrical interference from phones etc.
That RS-80 was one that used LORAN triangulation for wind finding, more modern ones use GNSS for wind finding.
I have a Casio FX-82ES and I get 9.000000007 with that formula at 18:55 in the video. Interesting way to spot the chipset though. Never heard of it before.
Love your reaction on the batteriser.
Nice office tan. Weren't you at the beach recently?
I just burn.
An Australian who burns in the sun? Are you sure you're not a secret Canadian? :-) On an unrelated note: any chance of a video about South Australia's "we don't need electricity all the time, do we mates?" approach to power generation? :-)
I had one of those TVs, got it at a second-hand market, it was white not pink. I thought it was neat. It had a selector for VHF/UHF, but as it must have been specified for the UK, it didn't have a switch behind it.
I love those old portable TVs, I see them in thrift stores all the time but sadly they are near useless now because there are no analog stations any longer and most don't have any sort of external input, so I always pass on them, as much as I love the look of them.
Did you forget some editing at 7:45?
Hi Dave, you teardown radioson RS80 reminded me that I had one in the shed, I collected it in about 2005 on one of my trips across the to the west from the BOM site at Ceduna on the WA/SA boarder, the blokes there love to have a chat and I spent 2 days there, the devices are all tested before they are loaded into the automatic deployment machine, it is worth a whole show just on that topic, but if you want I can send this one to you to compare, but they are made standard across the world, so changing them would be a big can of worms..
that little TV is cute af
I had 1 as a kid but it was read but black & white
still want one, not the bute one, but similar,because never had one as they were sold here. Saw several on our craigslist analog page, but they were in some kind retro electronics shops and they cost multiple tens of euros for some reason. In unknown condition and analog tv is dead even.
You should check the interference of the ecg project against devices that are not in the same loop as the ecg. You're closing a loop between the test leads the oscilloscope and your hand arm sensors etc etc..
EKG:
Noise is normal for any movement. even med grade hardware has it unless filtering is applied (built into monitors).
the colour codes are standard pretty much, those are the north american (AHA) ones.
"White's on the right and Smoke over Fire"
given its only got red and white, that's going to give you lead II
Ha!! The Batteroo never even raised his heart-beat even 1 BPM!!
Enough's enough Betteroo - when will you guys just go away? Talk about flogging a dead horse..
Anyone notice that Dave faked the screen video on the little TV? I guess it didn't even light up.
The big board i saw was a type amplifier do to symetri layout.
I was guessing that the symmetry was to send an amplified signal to each set of the speakers... guess not.
By far your best Batteriser video (not that there's anything wrong with the others)
'nuff said, mike drop, neeext :)
37:09 - my experience is very limited, and peripheral -- I was around when some other folks were working on a project for a balloon launch, and played a few minor roles in the project. That said, I can say that temperature was _very much_ a concern for things. We tested our build, for example, in liquid nitrogen... there's a write-up on it here: www.instructables.com/id/Thermal-test-chamber-for-edge-of-space-testing.-D/ ... not sure if that gives you any useful data, but it's about all I know. :)
8800 'peak watts' would STILL translate to at least 2KW 'RMS' :)
I'm guessing this amp is Class D.
Class D generally has only output MOSFET's. Not BJT's. This might be class AB with switching rails voltage regulators
at 17:00 this are the batteroo and the solar roadways guys asking you to turn green 😂
Capacitors under 0ºC is a big crap!
The amp is probably class H. The two MOSFETs will be switching rail voltages between low and high voltages depending on what the signal is doing. The diodes are likely commutation diodes.
Sanken are well known for making Audio power transistors - their primary speciality is being highly linear, but with plenty of power handling and high speed. 60MHz fT for power transistor's isnt that common.
When I was a kid I actually bought Mom one of those TVs for use in the kitchen
I had the portable TV with the SEE THROUGH case! :D
I also have an RCA color portable TV with a tiny CRT (about the size of 3x4 keys on a keyboard).
That RF stuff is the arcane science of tongue angles.
A few years ago I saw a really good ripoff of a Casio FX series at a dollar store. I wish I had bought it. It was about 99% identical to a real Casio including an FX model number but no branding anywhere on it.
If that calc is the one I'm thinking of, it's actually BETTER in several ways than the Casio inspiration!
Is your live webcam broken?
If it wasn't it would be working.
Ahh UHF... The movie that nobody remembers at all sadly.. It did (sort of) launch the careers of the guy who played Kramer on Seinfeld. And of course one Fran Dresher.. :) Miss Fine!!!!!!
Maybe the air dialectic capacitors shifted the output frequency dependent on barometric pressure, making the carrier an additional analogue telemetry.channel.
Not fan of the idea of using that function to test calculators. it's biased towards a specific processor and brand.
something to consider is that you are giving cos a tiny and insignificant value (angle) from sin. As such, you might want to invert the order for asin/acos and sin/cos so that you feed an actual workable angle to cos. Doing so on my old Casio gives me the perfect 9 you're looking for.
LOL, I'm from the same city in Portugal!!! Again, our CTT (the same flavor like Royal Mail...).
Greatings from this Portugues viewer!!! Thanks mate.