Use a Cheap PIN Diode as a Geiger Counter

opengeiger_logo

After the Fukushima nuclear power plant disaster, radiation measurement became newly relevant for a lot of people. Geiger-Müller tubes, previously a curiosity, became simultaneously important and scarce.

Opengeiger.de (English-language version here) has complete instructions for making a Geiger counter without a Geiger-Müller tube. Instead, this counter uses a PIN photodiode and some carefully chosen operational amplifiers. The total cost of such a device is significantly cheaper than the alternative: under $1 for the diode and around $5 for the rest. And since the PIN photodiode in question is used in many other devices, it’s not a niche component like a Geiger tube is.

The secret sauce is in component selection and tuning. Opengeiger uses the BPW34 diode because it is relatively common and has a large surface area, but also because it has a very low capacitance when reverse-biased. The first-stage opamp choice is also fairly critical. Considering that an average gamma radiation event produces only around 10 nanoamps for about 50 microseconds, a lot of amplification (100,000x), low noise, and high bandwidth are a must.

If you want to get started with this project, you could first browse through the explanation (PDF) to get an overview of the project’s goals, read up on all the technical considerations (PDF) or just head straight for the DIY instructions for the “Stuttgarter Geigerle” (PDF, schematic is on the last page). All of the documentation is chock-full of relevant references and totally worth the read.

A 1920’s Doorbell is Upgraded with 2010’s Technology

Doorbell

When you move into an old house, you are bound to have some home repairs in your future. [Ben] discovered this after moving into his home, built in 1929. The house had a mail slot that was in pretty bad shape. The slot was rusted and stuck open, it was covered in old nasty caulk, and it had a built-in doorbell that was no longer functional. [Ben] took it upon himself to fix it up.

The first thing on the agenda was to fix the doorbell. After removing the old one, [Ben] was able to expose the original cloth-insulated wiring. He managed to trace the wires back to his basement and, to his surprise, they seemed to be functional. He replaced the old doorbell button with a new momentary button and then hooked up a DIY doorbell using an XBee radio. [Ben] already had an XBee base station for his Raspberry Pi, so he was wrote a script that could send a notification to his phone whenever the doorbell was pushed.

Unfortunately, the old wiring just didn’t hold up. The push button only worked sporadically. [Ben] ended up purchasing an off the shelf wireless doorbell. He didn’t want to have to stick the included ugly plastic button onto the front of his house though, so [Ben] had to figure out how to trigger the new doorbell using the nice metallic button. He used the macro lens on his iPhone to follow the traces on the PCB until he was able to locate the correct points to trigger the doorbell. Then it was just a matter of a quick soldering job and he had a functional doorbell.

Once the electronics upgrades were complete, he moved on to fixing up the look of the mail slot. He had to remove the rust using a wire brush and sandpaper. Then he gave it a few coats of paint. He replaced the original natural insulation with some spray foam, and removed all the old nasty caulk. The final product looks as good as new and now includes a functional wireless doorbell.

We’re big fans of salvaging old-school home hardware. Another example that comes to mind is this set of door chimes with modernized driver.

Tube Headphones Rock Out While Keeping the Family Peace

tubeHeadphones

It’s hard being a kid sometimes. [Young] likes his music, but his dad is an overnight trucker. With his dad sleeping during the day, [Young] has to keep the volume down to a reasonable level. He could have bought some commercial headphones, but he wanted something a bit more customized. Rather than give up on his tunes, he built a pair of headphones with an internal tube preamp amplifier. [German language link -- Google translate doesn't want to work with this one but Chrome's translate feature works].

Two 1SH24B preamp tubes feed two LM386 amplifier chips, creating a hybrid amplifier. The 1SH24B tubes are designed to work on battery voltage, so a step up circuit wasn’t necessary. However, [Young] still needed to provide an 8 cell battery pack to run his amp. Speakers were a 3 way coaxial of [Young's] own design. He built the headphone frame using candy tins and cups from commercial headphones. A final touch was a window so everyone can see all that vacuum state goodness.  Considering that [Young] is only 16, we’re looking for some great things from him in the future.

If you don’t want to strap the tubes to your skull there are other options. But you have to admit it makes for a cool look. Starbucks here we come.

[Thanks Patrick]

Lux: A 100% Open Source Camera

luxCamera

[Kevin Kadooka] recently finished his open source camera. The Lux Camera is 100% open source. Lux uses no parts from other cameras – not even a lens! To date we’ve only seen this with achieved with pinhole cameras. [Kevin] isn’t new to camera hacking. He was the man behind the Duo camera, which had a successful Kickstarter campaign in February of 2013. Duo is a DIY camera, but it still required lenses from Mamiya-Sekor, and a shutter from Seiko. Lux is a different animal. It has a manual focus 65mm f/5.6 Single Element lens. The shutter is [Kevin's] own solenoid based leaf shutter design. Just as in the original shutter, an Arduino controls shutter operation and timing.

The main camera body and many of its parts are 3D printed. [Kevin] got some very nice quality parts from Shapeways 3D printing service. We have to say that some of the assemblies look a bit complex for desktop printers. However since everything is open source, anyone willing to put the time in could adapt them for the average RepRap or Ultimaker. [Kevin] has posted detailed build photos, as well as some photos taken with the Lux on his flickr stream. The pictures have  a decidedly holga-esque look to them, due in part to the single element lens. Even with this limitation, we love the idea of having a brownie style camera built completely from scratch.

Home Made CNC Reuses Printer Parts

Maker2

Do it yourself CNC machines can be never ending projects. Once you get one machine done, you want another. [Mario] found this out when he started work on his second CNC machine, TheMaker2. As its name implies, TheMaker2 is the successor to TheMaker1. It seems that [Mario] was trying to walk the fine line of precision at minimal cost. He wanted a rigid frame, so he chose to go with a moving table, rather than the moving gantry of TheMaker1. The frame is made up of galvanized steel stock, which makes it much stronger than many DIY CNCs out there. [Mario] had a friend weld the steel up for him, we hope he took the proper precautions when welding galvanized material.

Standard threaded rod was used as lead screws, with some very well made anti backlash nuts. Acme thread would have been a better choice here, however [Mario] doesn’t say if acme stock was available to him. Most of the mounts and small parts are made from easily worked PVC sheet stock. Precision rails were scavenged from old Ricoh copiers. Epson printers provided the tubing which became motor couplers.

One negative in this build are the stepper motors. [Mario] used NMB PM55L-048 motors he had pulled from HP printers. These motors have both a wide step angle (7.5 degrees) and a rather anemic torque. Thankfully [Mario] mentions upgrading NEMA 23 motors in the comments of TheMaker2’s instructables page.

Turning anything into a drone

drone

For his graduate project, [Jasper] wanted to do something with a quadcopter drone. Not content with simply building any old drone, he decided to make a kit that turns anything into a drone. Everything from a bicycle wheel, to a computer keyboard, and even a phone is more than able to take flight with [Jasper]‘s Drone It Yourself kit.

The DIY drone kit consists of a few 3D printed parts that include four clamps and mounts for the four engines. Also on board are ESCs, a battery, receiver, and an OpenPilot autopilot that will hopefully keep a drone in any shape imaginable hovering in the air. All this packaged in a sleek aluminum briefcase make it look like something out of an eccentric Bond film parody.

This project isn’t for sale – at least until the Brookstone catalog steals the idea – but you can get the bill of materials directly from [Jasper], just in case you’d like to make your own random flying object.

[Read more...]

Build an elevator controller, gain a friend for life

diy-elevator-controller

[Michael Ruppe] was working one day when a man named [Kevin] approached him for a bit of help with a project. It just so happened that [Kevin] was in the middle of constructing a DIY residential elevator and he needed assistance putting a control board together.

[Kevin] had no problem casting a forklift ram into his basement slab, nor installing a submersible pump in a custom-made hydraulic pit, but wiring up the controls for the device was just not something he was comfortable with. [Michael] was more than happy to lend a hand, and over the next couple of months the pair got things running nicely.

Instead of relying on a microcontroller, [Michael] built a control board that uses little more than a handful of relays and microswitches to get the job done – It’s certainly not hard to appreciate the controller’s simplicity.

It’s stories like these that remind us just how much the hacker community is willing to help out complete strangers with any task, big or small – you guys rock!

Stick around to see a short demo video [Michael] shot, showing the elevator in action.

[Read more...]

Follow

Get every new post delivered to your Inbox.

Join 96,699 other followers