Powering up a blue laser diode to 500mW
Note how it acts like a poor LED until 150mA, at which point the laser process fires

The 505B is an accurate, adjustable current source which allows for external modulation input.

It’s designed for low-noise (<1.5uA RMS) and it has a photo diode input, so with a calibrated light sensor, you can achieve constant power regulation.

Last but not least: it’s designed for maximum safety with two interlock circuits, one with a physical key.
Its internal design has a complex redundant output circuit, which ensures that the laser will NEVER illuminate unintended and it will NEVER exceed the chosen power setting.

A fancy current source indeed, a laboratory grade instrument

This video was shot wearing the appropriate safety glasses, be VERY CAREFUL when experimenting with lasers. Even a short duration reflection at this power level WILL damage your vision

Got my hands on this little gem recently, they’re hard to find in a decent state at a decent price tag. Got lucky though so now I have a dedicated laser diode driver in my lab
Not super high power, it maxes out at 500mA, but it’s enough for a whole range of experiments and it has a lot of nice safety and control features
It’s surprisingly complex inside, but nicely built and very clean. Doubt it’s seen many hours usage, the fan is just fine
#electronicsengineering #laser #testandmeasurement

Adding 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..

@va3db

This weekend was special: yesterday the baltic countries: Estonia, Lithuania and Latvia, disconnected from the Russian/Belarus 50Hz power grid, going ‘island mode’, controlling the 50Hz grid frequency themselves.

After more than a day of different stability tests, this afternoon, just before 13:00 CET, a connection to the European grid was established via Poland, so now the the three countries are in 50Hz sync with Europe.

I observed a small, undramatic, ‘burp’ in the frequency at the time of the event, and my wall socket is now in full sync with the measurement in Estonia, provided by #sympower️

Back to work on project Chowndolo! Improving the PCB design and making refinements using KiCad. Excited to take this to the next level...
#PCBDesign #KiCad #OpenSourceHardware #Electronics #Engineering #HardwareDesign #Maker #DIYTech #EmbeddedSystems #CircuitDesign #TechInnovation #ProductDevelopment #EDA #SchematicDesign #Prototype #IoT #DIYEngineering #ElectronicsEngineering #SoundArt #DigitalLutherie #MusicTech #ExperimentalSound #DIYInstruments #ElectronicMusic #InteractiveSound

My first #HB9CV #antenna, believe it or not, made from 5mm brake lines and a foot of 15mm copper pipe

I need it for a 70cm radio #foxhunt event in a couple days - looked different places for design guidelines, some of them came up with quite different results

Decided to just have go at it, based on a combination of what I could find in the legendary #Rothammel antenna book and some online sources and it turned out quite well

Resonance is a bit low, 431MHz, but it’ll do fine as a direction finding device: what I really want is the characteristic kidney shaped radiation pattern, allowing me to turn the antenna backwards, looking for a minimum in the received signal.

Funny to see how the #smithchart impedance plot has a distinct turn at the resonance frequency

Occasionally 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

What a score - genuine EPPLEY voltage cell, originally used for calibration purposes.

Even though it’s 66 years old, it still seems to work, it’s amazing

Stay tuned for a more thorough test under more controlled climatic conditions

I’ve been looking for an antenna for a permanent #meshtastic node in my attic and I found this one, along with 5m RF200 low-loss cable.

I know that this setup will most likely render me ‘excommunicado’ in the #meshtasticcommunity: “thou shalt always install thy node right below the antenna!”, but here’s the thing: I want to experiment with different hardware, I want to do some interference measurements at night (ever heard about the ‘Mammotion’ lawnmower which illegally jams 868MHz?) , AND I have a powerful 2m/70cm transmitter close to it, and I don’t want EMI issues on a sensitive 5V line.

Besides, the antenna has 3dBi gain and I measured the cable loss to 1.4dB at 868MHz, so given its better location, the numbers still come out positive

See that dip near 145MHz btw.? Need to do a test to see how much signal it’ll pick up from my VHF rig - don’t want to damage my LoRa module

#lorawan #electronicsengineering #rfengineering #rfengineer #hamradio hamr #testandmeasurement

Preparing a little curve tracer demo, walking my way through some different diodes

Starting from the left, an OA95 germanium, 1N4148, 1N4007, LEDs, a vintage 60V Selenium and finally, a zener.

#Easterquiz, what is this?

Correct answer and a demo will follow one of these days

An interferometer is a really cool laser experiment you can do at the bench

You need a laser diode with a built in photo diode sensor - not all of them have it. Keep the power low, and safe. I chose the ADL65052.
(Laser diodes are NOT like your common LED so if you’ve never played with them before, start with that)

Then build a transimpedance amplifier (a current to voltage amp), connect the output to an oscilloscope and here’s what happens:

The light can be reflected back into the laser, causing constructive and destructive interference. The sensor diode sees this as varying light depending on the distance to the reflector.

It’s REALLY sensitive, it’ll pick up vibrations of the surface of my bench

It’s a well described experiment, there’s a whole Wikipedia article on the principle. The physics behind it is quite sofisticated though - so it’s a neat experiment to replicate