Random Projects

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In this post I will document some of my smaller projects that don’t deserve a whole blog post of their own.

Radio Transmitter

Years ago I made this FM radio transmitter. It’s powered by a 9V battery and transmits the audio signal from the 3.5mm audio jack. The frequency is somewhere in the range a regular FM radio can receive.

DIY Mini FPV Camera

I made this DIY mini FPV camera for my racing quadcopter back in the day. Nowadays you can buy these small compact camera/transmitter combos already prebuilt for very cheap so it doesn’t make much sense to make your own.

It’s meant to be powered from the 5V output of the flight controller. The dip switches are used to set the channel of the transmitter. As you can see in the right image the camera produces a nice image. The only problem is that it tends to heat up quite a bit which is why I added a little heatsink at the bottom. However, this isn’t a problem as long as you are flying and there is a constant airflow camera/transmitter.

3D Printed Keycap

When I first got my DLP 3D printer I made a couple of test prints including this Pikachu keycap. I decided to paint the key cap, make a little enclosure for the mechanical keyboard switch, and use a 555 timer to turn on the backlight of the switch for some time. This was a kind of pointless project that I made just for fun.

The circuit is made from a 555 timer in the monostable mode that is powered by 5V from a USB connector.

Controlling a Pneumatic Piston With Arduino

This is a simple Arduino pneumatics controller I made as a test before using it as part of my spot welder project. The Idea here is to use a piston on a spot welder to close its the contacts together on the welding piece, weld the piece and release the contacts again.

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These were some of the smaller projects I made. I probably make some additions to this post in the future …

(update) Here is some stuff I added after I initially published this post:

Ionizer

I recently found an ionizer module(that I ripped out of an old hair dryer many years ago) in my parts box. I decided I would make a simple little ionizer by sticking the module into a case of an old broken access point I also had in my parts bin.

Here and here are some interseting videos on ionizers by bigclivedotcom.

DIY Networking Cabinet/Rack

I took the case of my old broken Solidoodle 4 3D printer and converted it into a networking equipment cabinet or “rack” if you can call it that. The switch and GPON modem are stuck to the metal case with a couple of neodymium magnets I took out of some old hard drives. The ISP router sits on the top shelf and the NAS and UPS are on the bottom.

The switch was originally sized for a regular 450mm rack. This was too big to fit into my DIY cabinet so I just took an angle grinder and cut off the sides of the switch to match the width of the PCB inside it(most of the case was just empty space). I also cut out a few slits for the intake and an exhaust hole for a standard 120mm PC fan. Now with the fan turned on everything in the cabinet runs cooler much cooler.

It’s not the most impressive home lab setup, but it’s better than it was before, just stacked up on a shelf. In the future, I really should get a proper rack, with a custom-built server, better switch, patch panel, bigger UPS, 10Gbps fiber optic cables, … Well, whenever I have the time … and then maybe I will get to upgrading it.

CT Clamp Current Meter

I found this old project I did in high school almost 10 years ago. The windows forms app measures the current by using a CT current clamp that plugs into the microphone port.

DIY ESP8266 Tasmota Timer

This is a quick, temporary DIY timer I threw together. It uses an ESP8266 flashed with the Tasmota firmware. I covered installing Tasmota in this post here.

Old Camcorder CRT Viewfinder

I recently got hold of an old camcorder and tore it down. One of the parts I decided to save for a potential future project was the viewfinder that has a tiny CRT monitor inside. I made a little adapter PCB so the viewfinder can be connected to an RCA video input.

I used an Arduino to generate a test analog video signal. I already wrote about this in this post here and how to display an actual image in this post here.

6502 Computer

I have made this 6502 computer by following along with the 6502 series Ben Eater made. I started this project many years ago, after I finished his 8-bit computer on a breadboard series(which I made in an FPGA instead, check it out here). Recently, I finally decided to finish up the project and make this quick overview of it.

Debugging some stuff while it’s still on a breadboard.

Uploading the machine code of the assembly.

SDR and GNU Radio

Recently, I was playing around with GNU Radio and the HackRF SDR. I made a few simple projects for fun and learning, as software-defined radio was on my “to learn” list for some time.

Additionally, I was considering using GNU Radio for my DIY radar project, which I will probably make a separate post about in the future. I still have to see what I will use to generate the chirp signal and then process the returned signal(sound card, GNU Radio, signal generator + oscilloscope combo).

LoRa and Meshtastic

Some time ago, I was playing around with LoRa WAN and Meshtastic. I got myself a few different boards. I 3D printed some enclosures for them, added batteries and even made a DIY antenna for one of them.

Powerbank from Old 18650s

I often try to reuse old 18650s, mostly from old laptop batteries, for power banks. You can buy these very cheaply online and fill them up with your own batteries.

I measure their internal resistance and remaining capacity, and if they are ok I reuse them. I try to match capacity and internal resistance and keep the batteries from the same batch together, or I add a protection circuit to them. Mixing and matching old batteries might not be ideal, but at least if they are in parallel, it’s not as bad.

Mini Portable LCD Screen

A very useful portable little LCD screen. It can be seen in this post before I 3D-printed a stand for it.

SBUS Inverter

Simple little SBUS inverter I built a while ago for my quadcopter.

RC Setup and Custom Built Quadcopters

I got into RC in 2015 when I built my first quadcopter. Eventually, I also built a smaller racing one. At first, I was using a NAZE32 for the bigger quad, but then switched to an ArduCopter flight controller.

Earlier in this post, I talked about some of the things I made related to my quads, like the SBUS inverter or the DIY 5.8GHz mini camera. Additionally, I also made a blog post about my DIY FPV goggles, a post about compiling Cleanflight/Betaflight and one about modifying the firmware to add back the GPS for F3 flight controllers.