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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" target="_blank">@va3db</a><a href="https://techhub.social/tags/signalsaturday" class="mention hashtag" rel="nofollow noopener" target="_blank">#signalsaturday</a> <a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener" target="_blank">#electronics</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener" target="_blank">#hamr</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/siglent" class="mention hashtag" rel="nofollow noopener" target="_blank">#siglent</a>

Søren KjærsgaardThe ‘Lambda Diode’ circuit, made from two J-FETs (one P- and one N-Channel) exhibits ‘negative resistance’ and has a ‘hysteresis’ curve when viewed on a curve tracer. A bit like a ‘tunnel diode’, actually. Circuits like these were a common way to make an oscillator from just a few components, as my next post will show. I always end up using my analogue <a href="https://techhub.social/tags/Hameg" class="mention hashtag" rel="nofollow noopener" target="_blank">#Hameg</a> scope for curve tracing in X-Y mode, it works a lot better than any of the digital scopes I have 🤷🏼‍♂️🙂 In fact, I have yet to experience a digital scope with even a half-decent X-Y mode.. Thanks for the inspiration <a href="https://mastodon.radio/@va3db" class="u-url mention" rel="nofollow noopener" target="_blank">@va3db</a> 🙂👍🏼<a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener" target="_blank">#hamr</a> <a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener" target="_blank">#electronics</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/keithley" class="mention hashtag" rel="nofollow noopener" target="_blank">#keithley</a>

Søren KjærsgaardSo when you have a bunch of jellybean JFETs (2N5457), time to burn, and a handful of 1uF bipolar capacitors… What to do.. 🤷🏼‍♂️🤓I decided to build a simple amplifier 😃 Although many find JFETs aren’t quite as intuitive as a regular BJTs, they’re not THAT scary 👻😂 and they’re easily biased, using a megaohm sized resistor from the gate to ground. To be able to do some more accurate calculations, I decided to measure the maximum drain current, IDSS, and the negative Gate-Source cut-off (pinch off) voltage, as they can vary significantly even between devices even from the same batch. A fun evening in the lab 😃<a href="https://techhub.social/tags/electronics" class="mention hashtag" rel="nofollow noopener" target="_blank">#electronics</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/EE" class="mention hashtag" rel="nofollow noopener" target="_blank">#EE</a> <a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener" target="_blank">#hamr</a>

Søren KjærsgaardAnother one of those “it’s me or the dumpster” finds… There’s really no civil applications in Ku band, or? Inspire me, please ☺️ If only I had a 17ish GHz oscillator, I could at least play a bit with it 🙂 <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener" target="_blank">#hamr</a>

Søren KjærsgaardOccasionally you come across a rescue scenario: it was literally me or the dumpster… So I adopted it, I now have a 20GHz frequency counter… 🤷🏼‍♂️😎The 5361B was never made for normal RF use, its primary application is analysis of pulsed radars. It does, however, fully support CW measurements, so although somewhat bulky, it’s a nice instrument to have around in the lab 🙂<a href="https://techhub.social/tags/testandmeasurement" class="mention hashtag" rel="nofollow noopener" target="_blank">#testandmeasurement</a> <a href="https://techhub.social/tags/rfengineer" class="mention hashtag" rel="nofollow noopener" target="_blank">#rfengineer</a> <a href="https://techhub.social/tags/electronicsengineering" class="mention hashtag" rel="nofollow noopener" target="_blank">#electronicsengineering</a> <a href="https://techhub.social/tags/hamradio" class="mention hashtag" rel="nofollow noopener" target="_blank">#hamradio</a> <a href="https://techhub.social/tags/hamr" class="mention hashtag" rel="nofollow noopener" target="_blank">#hamr</a>

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