Mastouille

Søren KjærsgaardAdding parallel circuit allows for the Lambda Diode to oscillate at a frequency determined by the LC resonance frequency. The result is an absolutely beautiful sine wave 🤩Note how the oscillation starts, once the supply voltage crosses where the current starts to decrease, ending up at the ‘negative resistance’ portion of its characteristic. This is likely the easiest and most clean oscillator I ever built 😃 I wonder if you can use a crystal or crystal f it would get damaged from the drive level 🤔 Maybe one of those vintage ones.. <a href="https://mastodon.radio/@va3db" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@va3db</a><a href="https://techhub.social/tags/signalsaturday" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#signalsaturday</a> <a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronics</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a>

Søren KjærsgaardI need a reasonably clean 4MHz oscillator for a <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/foxhunt" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#foxhunt</a> offset attenuator and decided to build one based on a J310 J-FET transistor. The output on the Drain is quite clean, but can’t be loaded much, so a I added a simple buffer based on BC547B 🙂It’s all pretty standard circuitry, and you can find all kinds of variants out there, but it’s still fun to see it spring to life 😃<a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a>

Søren KjærsgaardThe Icom IC-7000 I recently purchased is quite old and they’re known for having a bit of high frequency ‘hiss’ in the audio output. I doesn’t matter while using the built-in speaker, however it gets annoying when using high quality headphones. There is a fix, but it’s complicated and involves extracting a major PCB from the radio.I had some random two-way speaker filter in a drawer so decided to give it a go at reworking it, to become a 700Hz lowpass filter (I’m primarily a CW operator). It turned out really nice, even peaks a bit before rolling off. And the ‘hiss’ from the radio? Gone! 👍🏼😃<a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a> <a href="https://techhub.social/tags/icom" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#icom</a> <a href="https://techhub.social/tags/icom7000" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#icom7000</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/signalsaturday" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#signalsaturday</a>

Søren KjærsgaardIt’s <a href="https://techhub.social/tags/measurementmonday" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#measurementmonday</a> and I’m investigating a mystery coupler, a fellow ham asked me to test. It seems to be the happiest around 1.8-1.9GHz 🤷🏼‍♂️🙂 The coupled ports are -20dB down. What’s even more interesting, is the detector diode add-on it came with: you carefully insert the diode, a 1N21E replica, directly into the center pin of the N-connector 😳 Then carefully mount the outer capacitor shell with the BNC connector and you’re good to go. Since the diode now sits in its reversed position, the output will be negative and it works just fine 👍🏼🙂<a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronics</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/rfengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineering</a>

Søren KjærsgaardIt’s time to answer my <a href="https://techhub.social/tags/easterquiz" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#easterquiz</a>: it’s a ‘sweeper’, some would call it ‘Jammer’ 🤷🏼‍♂️🤓They come in all kinds of frequency bands and output power levels - be aware they may be illegal in your country. I ordered this to operate in a band covered by my <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> license and I have no intentions of ever transmitting into an antenna. In short, it uses a 555 timer to generate a 100kHz ramp signal which is fed to a 400-500MHz VCO. Center frequency and bandwidth can be adjusted by two trim pots. The output signal is then amplified - that’s all there is to it 👌🏻I fed the output through a 30dB high power attenuator, then split it to my spectrum analyzer (through another 20dB) and a detector diode to my oscilloscope. It’s not a completely calibrated setup, but the measurements seem to agree at about 1W ‘channel power’. Not much, not very efficient, but it works just fine 🙂👍🏼Hope you enjoyed it 😃😃<a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/rfengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineering</a> <a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronics</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/rohdeschwarz" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rohdeschwarz</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a>

Søren KjærsgaardEver wondered what happens when you switch on your bench supply, even when its output is set to OFF? Some supplies produce a nasty spike, powerful enough to damage sensitive circuits 😳⚡️This <a href="https://techhub.social/tags/gwinstek" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#gwinstek</a> GPE-4323 isn’t bad: into a 120R load it peaks at -4V and most energy is gone after 500ns. Some cheap supplies, however, can be much worse. So be careful out there and if you have a fancy digital oscilloscope, use some of that fanciness to test how your bench supplies perform. (Spoiler alert: Cheap isn’t always good ☺️👍🏼)<a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronics</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/engineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#engineer</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/electronicsworkbench" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsworkbench</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsengineering</a>

Søren KjærsgaardIt’s <a href="https://techhub.social/tags/signalsaturday" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#signalsaturday</a> and I’m continuing the <a href="https://techhub.social/tags/CuteGen" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#CuteGen</a>™️ test series by looking a bit at the harmonics 🙂 How clean is it?Starting at 1kHz I’m using my <a href="https://techhub.social/tags/Siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Siglent</a> <a href="https://techhub.social/tags/oscilloscopes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#oscilloscopes</a> powerful FFT functionality and with harmonics >60dB down, this little thing really is a decent audio function generator. I then moved to the spectrum analyzer and did some tests at (much) higher frequencies. Only included 10 and 30MHz here, but pattern is clear: harmonics are generally nicely attenuated, more than 60dB, although at the high end, it’s not quite that much, more like 50dB and a sub-carrier spur appeared as well. Makes me wonder how well the 60MHz version performs 🤔<a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/rfengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineering</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronics</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/uni" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#uni</a>-t <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a>

Søren KjærsgaardI wanted to see if there was any visible pattern in the flicker sequence of the small LED ‘Candle’, so I used the <a href="https://techhub.social/tags/digilentinc" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#digilentinc</a> <a href="https://techhub.social/tags/digitaldiscovery" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#digitaldiscovery</a> and recorded two minutes of ‘flicker’. I used some vintage 74LS123 and 74LS132 to ‘signal condition’ so I got two outputs: the raw signal which has PWM (brightness) and a sequence with a pure on/off, stripped from the PWM. I found no reoccurrence during those two minutes 🤷🏼‍♂️ So the random generator is likely based on some analogue circuit rather than being shift register based. Other fun facts: the raw PWM frequency is about 350Hz. I found PWM levels (brightness) from 30% to 90%. It’s mostly 100% on though, only occasionally dipping at those random (flickery) events. And everything in the flicker timing seems to revolve around intervals of 100ms, occasionally a 50ms offset may be added/subtracted, but only once in a while.. 🤔<a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronics</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/xmas" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#xmas</a> <a href="https://techhub.social/tags/engineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#engineer</a> <a href="https://techhub.social/tags/digilent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#digilent</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/electronicscuriosities" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicscuriosities</a>

Søren KjærsgaardThe 74LS123 is ‘retriggerable’, this means that if it gets retriggered while already active, it starts all over, keeping the output state ‘high’ (or ‘low’ if inverted) for the designed output pulse duration until the next trigger signal arrives.This basically means that if the trigger signal occurs at shorter intervals than the output pulse duration, the output will stay active permanently. Why would you ever want this? One application could be to strip off some modulation of a digital signal, as an example the flickery LED candles.. They’re pulse width modulated: I can remove this with the 74LS123 after which, the random flicker sequence will be ready to capture and analyze 🙂Stay tuned for my next post 👌🏻🤓<a href="https://techhub.social/tags/frequencyfriday" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#frequencyfriday</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/engineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#engineer</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/ttl" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#ttl</a> <a href="https://techhub.social/tags/digitaldesign" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#digitaldesign</a> <a href="https://techhub.social/tags/ttlelectronicas" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#ttlelectronicas</a> <a href="https://techhub.social/tags/electronicsdesign" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsdesign</a>

Søren KjærsgaardInspired by aircraft IFF interrogator antennas, I decided to build my own array - how hard could it be 🤷🏼‍♂️🤓 As it turns out, not very hard at all 😃Playing with antennas at higher (GHz) frequencies means that you can get reasonably good results even at the bench, as shown here. To prove a concept you don’t need large testing facilities, a bit of absorber panel will do 🙂Found a readymade 4-port 180deg coupler (nick-named a ‘rat-race’) and used two 2.4GHz sleeve antennas, then sweeped a source in front of them. The deep notch at the ‘delta output’ is clearly visible when the source is positioned right at the mid point, in front of the two antennas. I’m quite surprised how easy this was, considering the complexity of what is going on here 🤷🏼‍♂️🙂I have very few friends who’ll understand and appreciate the coolness of this experiment, you know who you are ☺️<a href="https://techhub.social/tags/rfengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineering</a> <a href="https://techhub.social/tags/measurementmonday" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#measurementmonday</a> <a href="https://techhub.social/tags/rfengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineering</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a>

Søren KjærsgaardOrdered a couple of cheap BNC high-power attenuators, 3 and 6dB. “DC-3GHz” is a bit optimistic, but I found them nice and flat up to 1GHz, which is way above the frequency area of my application. So what’s going on here? 🤷🏼‍♂️☺️ Stay tuned, hints are in the tags 👌🏻<a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/sota" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#sota</a> <a href="https://techhub.social/tags/qrp" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#qrp</a> <a href="https://techhub.social/tags/cwops" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#cwops</a> <a href="https://techhub.social/tags/portableops" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#portableops</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/testgeartuesday" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testgeartuesday</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/rfengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineering</a>

Søren KjærsgaardInspired by <a href="https://techhub.social/tags/keysightlabs" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#keysightlabs</a> and <a href="https://techhub.social/tags/danielbogdanoff" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#danielbogdanoff</a>, latest YouTube video, where he uses a super nice <a href="https://techhub.social/tags/keysightoscilloscope" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#keysightoscilloscope</a> to demonstrate reactive (negative) power, I decided to make my own setup and replicate his experiment.I don’t have an advanced scope as the one he used, but I can create a voltage vs current phase difference by changing the frequency of a signal I pass through an RC circuit. Measuring the current with a differential probe, lets me multiply current and voltage and display a power curve on the oscilloscope (sorry for the weird colors, my camera messed up). As you can see, with a phase difference between voltage and current, I get negative power: the top curve begins to move below zero. At 90 degrees difference, the power would average zero which is why inductors and capacitors never really heat up (besides the resistive loss ofc) 🙂<a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronics</a> <a href="https://techhub.social/tags/signalsaturday" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#signalsaturday</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/micsig" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#micsig</a> <a href="https://techhub.social/tags/engineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#engineer</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a>

Søren KjærsgaardI picked up the little 3-band Mountain Topper at the Danish <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> fair - first test: does it transmit? It sure does 😃 Nice and clean signal, about 4W output with 10V supply. It’ll be fun to try it out in the wild, I might bring it on a <a href="https://techhub.social/tags/SOTA" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#SOTA</a> mission 🙂My test setup uses 20dB coupler with another 30dB attenuation added to protect my spectrum analyzer. The load is a 30dB attenuator which can handle 10W, more than enough 👍🏼 More to come! 🙂<a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/hamradioportable" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradioportable</a> <a href="https://techhub.social/tags/qrp" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#qrp</a> <a href="https://techhub.social/tags/cwops" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#cwops</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/rohdeschwarz" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rohdeschwarz</a> <a href="https://techhub.social/tags/minicircuits" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#minicircuits</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/rfengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineering</a> <a href="https://techhub.social/tags/lnr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#lnr</a> <a href="https://techhub.social/tags/mountaintopper" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#mountaintopper</a>

Søren KjærsgaardYesterday I did a small experiment, at a local <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> club online meeting. It’s a current generator, not even a good one (temperature stability) but to demonstrate the ramp voltage when charging a capacitor at constant current, it’s just fine 🙂I then pulsed the power supply ON/OFF at a square wave cycle. Yellow trace is the 5V supply, Cyan shows the current measured with a differential probe across the 2k2 resistor, and Magenta is the voltage across the capacitor. You can see a classic discharge curve when the supply shuts off and based on the 90-10% elapsed time, the equivalent discharge resistor is some 2k (from 2.2*R*C). Quiz: how does it discharge, where is the 2K resistor? The answer is as surprising as it’s simple, here’s a hint: when flipping the transistor 180, so C<->E and vice versa, the circuit still works… 👌🏻🙂Simple circuits often hold surprises and they can teach us a lot of basic things 🙂<a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/engineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#engineer</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a>

Søren KjærsgaardA debate came up at work: what happens to the wanted signal when an interferer pushes the LNA into compression? Let’s try it! 🙂Using A LOT of attenuation, I merged a 7MHz carrier (my wanted signal) with a stronger 25MHz interfering carrier. Stepping up the amplitude on the 25MHz signal, finally pushes the amplifier into compression: it’s gain drops and it becomes highly unlinear. Mixed products of the two carriers appears, as well as the 2nd harmonic of the interferer. The 7Mhz carrier is still there, but since the amplifier now has less gain, it drops in amplitude.Any <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> operator has experienced this on a crowded 40m band at night, in fact even worse, because numerous powerful stations mix and creates a lot of spurious noise on transceivers with low intermodulation performance.<a href="https://techhub.social/tags/rfengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineering</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a> <a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronics</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/minicircuits" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#minicircuits</a>

Søren KjærsgaardTesting the UAF-41 universal filter from <a href="https://techhub.social/tags/burrbrown" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#burrbrown</a> 🙂Pure vintage power, this little gem like has been dormant since it left the factory in 1979 and it still works just fine 😃<a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronics</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamr</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#siglent</a> <a href="https://techhub.social/tags/engineer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#engineer</a> <a href="https://techhub.social/tags/vintageaudio" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#vintageaudio</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#testandmeasurement</a>

GerbilEngineerNow, to get around to the two <a href="https://makersocial.online/tags/logicanalyzer" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#logicanalyzer</a> pods and all the grabbers. I had code that would run fine from the <a href="https://makersocial.online/tags/89C52" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#89C52</a> memory, but wouldn't run from the <a href="https://makersocial.online/tags/eeprom" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#eeprom</a>. I had verified that the static ram worked, but the EEPROM seemed to be acting odd. My nice <a href="https://makersocial.online/tags/Siglent" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Siglent</a> scope only has 16 logic channels. Not enough to watch the latched address bus and the data bus. Yes, I could have done it, but why not break out the <a href="https://makersocial.online/tags/HP1532B" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#HP1532B</a>? Plenty of channels there.

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