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nRF24L01+ Radio Spectrum I have now managed to investigate the radio spectrum output of the nRF24L01+PA/LNA module as shown... The constant carrier is shown to be present at 1420068 KHz = 1420.068 MHz = 1.420 GHz approximately on the SDR frequency scale. This is the IF (Intermediate...

That scanner example you gave me is brilliant. Its worth sharing the results to show not only how to transmit constant carrier, but also how to use the receiver to monitor activity in the WiFi spectrum. I'm very impressed. The nRF24L01+ device has a built-in low noise amplifier. So with just a...

That's a great example. Thank you Paul. I'll test and post results.

I'm playing with NRF24L01+PA/LNA modules and Teensy 3.1. Having good success so far. I wondered if anyone has managed to switched on "Constant Carrier" via Teensy. I'd like to have a look at the carrier on my SDR radio using HDSDR. My basic SDR hardware only reaches 2.0 GHz, but I bought a...

Worked beautifully. Thank you.

Just started with NRF24L01. Not used these boards before. Hit a compile issue with "Serial.printf". I have modified some code that I already use the SPI bus for on an ADF4351 board (which works fine). I have included two new "includes" as shown here... #include <stdint.h> #include <SPI.h>...

I was just thinking that it might be useful to be able to "synchronise" two Teensies together - in sort of "Lego" brick fashion. Perhaps allow one system clock to influence another one (or maybe even more), such that more than one DAC could be synchronised. There may be other advantages of such...

Will the 1170 have DACs as peripherals? These are useful to "glue" the digital world to the analogue world. (Note for our US cousins... there's no such thing as "gl") Tee hee.

Comparator Stand-Alone Test Here is a little help with using a T4 Analog Comparator. It uses the peripheral ACMP3. Normally, the ACMP3 output is available on pin AD_B1_14 (see page 295 of iMXRT1060 Ref Manual Rev2). But this is on the underside of the T4 board on Teensy 4 pin 26. I like to use...

Not sure your principle of using the analog comparator in this way is the best method for creating a Frequency Counter. There is an "overhead" in time to be paid for calling an ISR subroutine and if you do this on every zero crossing, then you will waste a lot of cpu time just dumping registers...

Thanks MarKT. That makes sense of the experiment results. Didn't realise that Schottky was so leaky (must remember that). Your comment on CMOS and latchup is valuable. Over voltage on any analog pin is undesirable so if we can hammer out a good, cheap, and simple defacto method, then this is...

Sdm40e20ls This surface mount diode SM40E20LS looks like a real beauty. The "typical" graph in the data sheet shows less than 0.3 volt drop for even 100 mA at 25 degC. If you could employ 100 mA into a diode for the permitted headroom of 0.3v, then even a 1K would allow you 100 volts excess...

Stop press Woah - hold everything... It does NOT look like there are internal diodes such as Fig 35 suggests. The assumption that all to the right of point VADIN was internal is NOT correct as far as my experiment a few minutes ago has indicated. Either this, or if they are there, then they...

iMX RT1060 Data Sheet A very interesting question - the protection of Analog inputs by NXP. Searching the NXP web site today, the iMX RT1062 is not listed (?), but the iMX RT1060 and iMX RT1064 are listed. Both have a Fig 35 in the data sheet (see...

I hope others will study and make some useful comment. Quite a lot here to think about...

Interesting Tom. I too had considered mattress inflators as a pressure source. You success with flow sensors has my respect. Its a tricky subject. My point about failure modes is - like software production - probably the hardest nut to crack in production engineering. Any authority (such as the...

Magnificent. A remarkable effort and an impressive result. If you can spare the time, I would love to read about your thoughts and problems as you went through the phases from initial ideas/conceptions to experiment and testing. What is the pressure generator? How is this controlled? Have you...

When giving advice it can be a little bit of a worry. No-one wants to give advice that could end up frying your kit. And this is the problem with a question such as you try here to put into words. My first advice is - take a sheet of paper and a pen - now draw the arrangement with every...

Hi. Hope you have figured out the diode symbol by now. You asked - in post #1 - which way around a diode should be soldered. I confess that the symbol is confusing. But there are clues to "which way around" if you look carefully. Take the diagram that you first referenced for Sparkfun. I'm...

The Si5351 Clock Generator chip has several excellent mentions in this forum previously, but I wanted to create a very simple design that anyone can put together in a few moments with a breadboard. This article is really a simple "How To" for beginners. Lots available on eBay. Here is what I...

Also... for a voltage division, you will need R1 and R2, where R1 is between signal source and pin, and R2 is between pin and GND. The division is then R2/(R1+R2)*Vsig. For a simple 3:1 division, R1=20K and R2=10K would work if the sampling is not too fast. Best thing is to test it with a known...

From your description, it is difficult to understand what you are trying to do. This thread may help... https://forum.pjrc.com/threads/28722-Teensy-3-1-Analog-pin-ADC-impedance. A.C. alternating signals are also a different consideration to D.C. When dealing with signals above the "Vin"...

New test technique Interesting developments are now happening with COVID-19 antigen testing (the swab test - to see if you are currently infected). There is a new technique called LAMP (Loop mediated isothermal AMPlification) which is an alternative to using the PCR method. Turns out to be much...

The invisible enemy? Would it be possible to view and detect SARS-CoV-2 using a conventional optical microscope? This corona virus has dimensions between 70 - 90 nm for a single virion particle. With an optical microscope, conventional wisdom states that objects smaller than about 200 nm...

@jimmyson - Which country do you refer to?

Energy considerations One aspect of cellular infection by viruses - that has important implications for the symptoms we shall experience - is the demand for ENERGY. Most of us have experienced the intense feeling of being tired and drained when sick with flu. But we probably have not considered...

I think you have something like Omeprazole in mind? Which is a PPI for GERD. My guess is (and it is a guess) that different drugs will be specific for different types of cells. So Omeprazole may be a remedy for gastric issues, but may not be of use in alveoli. Chloroquine can only be a temporary...

The mechanism by which the drug Choroquine might work is extremely interesting... It appears to be as simple as the "antacid" control of a fluid. Chloroquine will elevate the pH of a solution. These corona viruses have a "Capsid" container whose outer coating consists of a lipid/fatty membrane...

@KurtE - Simulations are good teachers - a picture is worth a thousand words. They are good at illustrating an event that you know for certain happens, but they are poor predictors of events that you are not sure of. There are a lot of good reasons for wearing a face mask. My biggest is...

Interviews with Prof Racaniello This guy Prof Vincent Racaniello is well worth listening to directly about SARS-CoV-2 and COVID-19. He did an interview with Ethan Evans (Greater Seattle Area, U.S.) about five weeks ago (https://youtu.be/NGcdLm_1h5w). It last for two hours, but is a real gem...

Came across this recent series of lectures on VIROLOGY which members may find interesting... https://youtu.be/lj3NhPgOoX4 Prof Racaniello makes a number of references to SARS-CoV-2, so very pertinent to today. Lecture#1 sets the scene very well, but Lecture#2 is more interesting. A number of...

@MatrixRat - How is your project#1 coming along? I have now logged a fair number of days of manual body temperature readings - and learnt a few things. My lowest (accurate) data recording is 35.7 degC. A fair number of 35.9's. My highest is 36.8. The low readings occur when I first get out of...

My take is that its his role as Prime Minister which is truly significant. As if things are not bad enough, this could turn the UK upside down (again) in hours. Parliament was suspended early and has no fixed date yet for returning. Consider too that he is one of the few people responsible for a...

Serious development in the UK It has just been reported on UK news channels that Boris Johnson, our Prime Minister, has been admitted to hospital. He placed himself in self-isolation 9 days ago. We expected (if he had a mild form of the COVID-19) that he would have been back in the public arena...

Transistors could be the answer to testing Came across a very intriguing article today. Biological sensing transistors, known as "BioFETS" https://cardeabio.com/field-effect-biosensing-technology/. These are transistors based upon GRAPHENE rather than SILICON. The "gates" of these transistors...

Mercedes F1 Ventura CPAP device Some more info now available on the Mercedes F1 CPAP device. You can find a picture of the blue hand-sized gadget about half-way down this webpage https://edition.cnn.com/2020/03/30/tech/mercedes-f1-breathing-aid-coronavirus/index.html Here is my educated guess...

@slomobile - The idea of using NMR/MMR as a specific SARS-CoV-2 test (wild speculation) would be attractive if this could be engineered into something like a "finger tunnel", where insertion of a digit could produce a result within minutes. The problem would be "how to recognise" the signals in...

CPAP in the news again... https://www.bbc.co.uk/news/health-52087002 I note the Formula 1 racing techies involvement. Patient gets blown up like a balloon when the turbo kicks in!

Cheap Digital Thermometer Teardown Cheap digital thermometers seem to be still widely available on eBay. I ordered two yesterday. I am using one that I've had for a long time for my own measurements, and I wondered about battery life. Can't easily change it on my model so I wanted to know...

Good reference. Well done. Here is its spec (https://e-vent.mit.edu/clinical/key-ventilation-specifications/) and here the original article(https://e-vent.mit.edu/wp-content/uploads/2020/03/DMD-2010-MIT-E-Vent.pdf). If anyone is already experimenting, share your thoughts and maybe some pictures?

The new "Emergency Powers Act" came into law last night throughout the UK. There is a whole bunch of things in it. One likely to be used quickly will be a £30 instant fine for being caught on the streets without an "accepted" reason. Also, coughing or spitting at police will likely incur jail...

Hi Kurt, reading the article, my take is that this COVID EMERGENCY VENTILATOR is for home use. The air will be full of contaminated aerosol. The description even explains that it sucks in the ambient atmosphere and cleans it up. This is good, for it should reduce the concentration in the family...

Project#2 related: Here is an interesting example of what can be done (with effort and the right resources)... (its CPAP)...

This links with a (lengthy) facebook thread for further details. I don't use facebook but my wife does and eventually I found this GoogleDoc...

@MatrixRat: Now you're talking mate. Thinking like this is needed for Project#1. Don't worry about the software - lot's of us here to muck in with that. Just think, if we optimised the design, the US Fed Government might buy millions to stimulate the economy. Ford motors could switch production...

Can I make a request please for all to amend your forum profile to include your country (and/or state for the larger continents). Then we can appreciate what is happening and where. Thanks. Interesting info from these sources...

Continuous monitoring is a toughy. What about a 10 MHz crystal sensing body temp as part of an oscillator. The radiated frequency can then be monitored remotely by near field radiation for logging. Once fitted, capacitive changes would average out. Large ppm/degC an advantage here - many cheap...

Change in the UK tonight - Monday 23 MAR 2020 We have just had a broadcast at 8.30pm tonight on national TV from our Prime Minister, Boris Johnson... The UK is now in partial LOCKDOWN with immediate effect. This applies to all citizens. All "non-essential shops" are closed. People are only...

@slomobile - Yes, gathering data is vitally important. I'm persuaded to "flip" the project management sequence. Or even discuss several "aspects" in parallel. If we can brainstorm and agree the important stuff, then maybe the project framework needed will become clearer. You make many good...

Gosh, they are tiny, 2.5 mm square and 1 mm high. Teensy peripherals should be fairly easy part of a Project#2 design. However, getting delivery may not be so. My biggest concern is the mechanics/bellows part. How do you make a home made bellows for a BiPap type design? And motorised operation...