Hackaday Links: Summer, 2015

[Elia] was experimenting with LNAs and RTL-SDR dongles. If you’re receiving very weak signals with one of these software defined radio dongles, you generally need an LNA to boost the signal. You can power an LNA though one of these dongles. You’ll need to remove a few diodes, and that means no ESD protection, and you might push the current consumption above the 500mA a USB port provides. It does, however, work.

We’ve seen people open up ICs with nitric acid, and look inside them with x-rays. How about a simpler approach? [steelcityelectronics] opened up a big power transistor with nothing but a file. The die is actually very small – just 1.8×1.8mm, and the emitter bond wire doesn’t even look like it’ll handle 10A.

Gigantic Connect Four. That’s what the Lansing Makers Network built for a Ann Arbor Maker Faire this year. It’s your standard Connect Four game, scaled up to eight feet tall and eight feet wide. The disks are foam insulation with magnets; an extension rod (with a magnet at the end) allows anyone to push the disks down the slots.

[Richard Sloan] of esp8266.com fame has a buddy running a Kickstarter right now. It’s a lanyard with a phone charger cable inside.

Facebook is well-known for the scientific literacy of its members. Here’s a perpetual motion machine. Comment gold here, people.

Here’s some Hackaday Prize business: We’re giving away stuff to people who use Atmel, Freescale, Microchip, and TI parts in their projects. This means we need to know you’re using these parts in your projects. Here’s how you let us know. Also, participate in the community voting rounds. Here are the video instructions on how to do that.

Making a 20dB Low Noise Amplifier for a 400MHz radio

[Will] recently tipped us about a 400MHz Low Noise Amplifier (LNA) module he made. His detailed write-up starts by explaining the theory behind an amplifying chain. Assuming a 50 Ohm antenna system receives a -70dBm signal, the total peak to peak voltage would be less than 200uV (.0002 volts). If the first amplifying stage doesn’t consist of an LNA, then the added noise would later be amplified by the other elements of your system.

[Will] then detailed how he picked his LNA on Digikey, mainly by looking for one that had a less than 1dB Noise Figure. His final choice was the Sky65047: a small budget-priced 0.4-3.0GHz low noise amplifier with a theoretical gain of 20dB at 400MHz. He made the PCB you can see in the picture above, removing the soldermask on the signal path in order to lower the permitivity. Because of a few mistakes present in the application note, it took [Will] quite a while to get his platform up and running with a 20dB gain but a 4.5dB NF. He also measured the input return loss using a directional coupler, which ended up being quite close to the datasheet’s 14dB number.