### LEAP#195 Coil Resonance and Inductor Testing

I've been trying to do some RF experiments, but instead being driven mad by hand-wound coils that never seem to behave as the standard coil inductance calculations would lead us to believe.

As always, it's w2aew to the rescue with a neat deconstruction and demo of a circuit for coil or inductor measurement.

I built the circuit out, and was easily measuring down to 10µH on a breadboard, and sub-1µH once I put the circuit on a hacked up copper board with islands. Using the LC circuit resonant frequency formula, it's possible to work backwards from known frequency and capacitance to determine the inductance (wolframalpha is great for this).

So now I hope to get back into some RF without the nagging doubt of not really knowing what my coils are doing!

As always, all notes, schematics and code are in the Little Arduino Projects repo on GitHub.

Here's a beautiful trace of a (nominally) 10µH choke with a 150pF capacitor. I measure the frequency at 4.26MHz, therefore an actual inductance of 9.3µH .. pretty close!

Even with a super-bodgy 4.5 turn coil whipped up on the spot and put in parallel with a 30pF capacitor, I'm still getting a decent oscillation at 34.09MHz for a calculated inductance of 0.73µH

And here's the board delivering the results:

### LEAP#194 DIY ESP8266 DevBoard

With the funding of the MicroPython on the ESP8266 campaign, my interest in the ESP8266 is rekindled!

I have an ESP-01 module lying around, but I'm a bit tired of wiring it up a breadboard again. So here is a little "devboard" I whipped up on a 4x6cm protoboard and hot-glued to a business card holder.

Now it's plug'n'play - add power and plug in a USB serial adapter and I'm good to go.

As always, all notes, schematics and code are in the Little Arduino Projects repo on GitHub.

### LEAP#193 PoV LED Shake Stick

This AT89S52-based "shake stick" kit pops up all over the place for a few dollars. I built it and hey, it works great!

But it's not packaged to be easily re-programmed for other messages or graphics. So started my sleuthing.. which turned into a fascinating story.

It seems the kit was originally designed and built as a uni project by Zheng Zhong Xing 兴向荣 (aka zhengzhongxing39) studying Control Technology and Instruments/Principles and Applications at a Chinese University. Reportedly "... soldering was troublesome, with lots of changes and no solid basic skills, so burned out the first board" ;-) But it seems persistence paid off, and ended up commercialising the kit and starting electronics business and taobao store where you can find this kit and many others.

As always, all notes, schematics and code are in the Little Arduino Projects repo on GitHub, including my annotation of the source code and schematic for the shake stick.

### LEAP#192 Sagrada Família model with LED effects

The Basílica i Temple Expiatori de la Sagrada Família has been under construction since 1882. The magnitude of the vision driving the project - both physically and creatively - is striking, especially at first hand.

Then you see the work in progress - the cranes, scaffolding, workers scurrying around the site. But that is what I think really brings it to life. This is not a frozen, finished statement of something other-worldy. It's a vibrant expression of the hope and aspirations of a whole bunch of people working together.

In other words, it is the ultimate maker project! Personally, I think it will be a sad day when someone declares it actually "finished".

Now at the extreme other end of the maker-scale is this neat little paper nano Sagrada Familia kit that I picked up in my travels.

I've "electrified" it to some extent with some LowVoltageGlowingLEDs that animate the background, just running off a 1.5V supply. Although I think I could have slowed down the LEDs even further.

A nice effect I think..

As always, all notes, schematics and code are in the Little Arduino Projects repo on GitHub.