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A simple RF switch using bipolar transistors

A simple RF switch using bipolar transistors

I am currently working on a project that requires me to switch signals in the range of 1-30MHz. I could probably get away with using regular relays, but they’d be rather noisy as I have about 10 signals that need to be switched at the same time. Reed relays would be more quiet, but they can be rather expensive and often have only one contact. I also wanted to avoid any special ICs such as off-the-shelf RF switches or PIN-diodes…

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A simple AM regenerative receiver for shortwave listening

A simple AM regenerative receiver for shortwave listening

I recently built a simple AM receiver for listening to shortwave radio. The circuit uses just 4 transistors in total, can be built on a breadboard and works pretty well despite it’s simplicity. It works as a regenerative receiver, which means that some of the amplified RF is fed back to the input. This greatly increases sensitivity and selectivity at the cost of having an extra potentiometer that has to be tuned, since too much feedback will cause oscillation. Another…

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Lawnmower repaired with 3D-Printing

Lawnmower repaired with 3D-Printing

I recently repaired our lawnmower and thought I’d share some pictures of it. The gasoline powered push mower is front wheel driven via ring gears that are part of the plastic wheels.As you can see in this picture, some of the teeth inside one wheel stripped which is really annoying because the driving power cuts out half of the time. To fix this, I decided to replicate this section of the ring gear with my 3D printer and glue it…

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DIY Circuit Boards: A slightly different approach (Part 2)

DIY Circuit Boards: A slightly different approach (Part 2)

In the first part of this series I explained why having a PCB prototyping setup at home can be beneficial. In this part I will describe the details of the process and show some of my results along with the do’s and dont’s.Before beginning I want to repeat that I did not come up with this method, it was Marco Reps who showed it before on YouTube. Also, this process requires dangerous tools and chemicals. Here is a list oft…

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DIY Circuit Boards: A slightly different approach (Part 1)

DIY Circuit Boards: A slightly different approach (Part 1)

In the beginning of their journey, most hobbyists use perfboards or stripboards to assemble their circuits permanently. These boards allow for a lot of flexibility, but the act of wiring any circuit consisting of more than just a handful of components can become quite painstaking. Fortunately, professional PCB manufacturers (like jlcpcb.com for example) offer their services at exceptionally low prices nowadays, so getting your design produced and shipped to you door is affordable for many electronics enthusiasts. However, this option…

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