hardware

1831 Articles

Seven Decade Programmable Resistor

September 18, 2013 by 50 Comments

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[Gerry Sweeney] was tired of messing around with resistors while prototyping his projects, so he decided he wanted a resistor decade box. The problem is they are typically big and rather expensive ($100+). Unhappy with the selection available for purchase, he decided to design his own.

In the accompanying video, he shows off his first attempt after being inspired by a past post we covered that used a combination of resistors and thumbwheel decimal switches. He modified the design a bit and used surface mount resistors instead, which made for a fairly compact and convenient seven decade resistor box. But he still wasn’t happy with it.

He decided to design his own PCB instead. The simple design utilizes surface mount resistors to conserve space, and jumpers to select the resistance. No bulky switches get in the way and it’s fairly cheap to produce.

Check out the great video explanation of the project after the break. He also shows off the insides of a commercial resistor decade box!

Continue reading “Seven Decade Programmable Resistor” →

Explaining The Low Level Stuff You Don’t Know About ARM Programming

September 17, 2013 by 8 Comments

Most of us don’t realize how spoiled we are with the different development environments available on the internet. If someone wants to start a blank project on a new [ARM/DSP/…] platform, he usually fires up the dedicated Integrated Development Environment (IDE) and starts coding a C/C++ program. However, there are many initialization routines and scripts required with your program before it can run correctly. In his great article, [Andrew] explains to us what these are by starting a blank project without using any IDE.

As you can see in the above picture, [Andrew]’s project is made around an Atmel SAM4E microcontroller. The chosen toolchain is the arm-none-eabi-gcc from GNU Tools for ARM Embedded Processors. The first part of the article starts with a simplified explanation on how/why your code and variables are split into different memory sections (.bss, .data, .rodata, .text), then [Andrew] details how the linker script will put these sections at different physical addresses depending on your microcontroller’s memory layout. He also shows us how to take care of the stack placement, vector table, variable (non)initialization, and C Runtime. For information, the latter is executed when your processor starts, it is in charge of setting up the stack pointer, initializing the RAM, setting up the standard library and calling the main().

A very nice introduction on the very low level routines running on most processors out there.

High Pressure Air Compressor Using A Pair Of Refrigeration Compressors

September 17, 2013 by 52 Comments

[Ed] from Ed’s Systems, aka [Aussie50] took some time to demo his high pressure Frankenstein air compressor he stitched together from two refrigeration compressors. The two Danfoss SC15 compressors can produce upwards of 400psi and can run all day at the 300 psi range without overheating. The dual units may get up to pressure quickly considering the small accumulator “tank”, but high CFM isn’t the goal with this build. [Ed] uses the system to massacre some LCD panels with lead, ball bearings, and other high speed projectiles shot from a modified sandblasting gun. Just a bit of air at 400 psi is all you need for this terminator toy.

Don’t think the destruction is wasteful either; [Ed] strives to repair, rebuild, reuse, repurpose and a few other R’s before carefully separating and sorting all the bits for recycling. This modification included lots of salvaged hardware from older teardowns such as high pressure hoses, connectors, accumulator and pressure cutoff switches.

At first it seems strange to see something engineered for R22 refrigerant working so well compressing air. Morphing refrigeration systems into air compressor service is something [Ed] has been doing for a long time. In older videos, “fail and succeed”,  [Ed] shows the ins and outs of building silent air compressors using higher capacity storage tanks. Being no stranger to all variations of domestic and commercial refrigeration systems, [Ed] keeps home built air compressors running safe and problem free for years.

Don’t think this is the only afterlife for old refrigeration compressors, we’ve seen them suck too. You’ll get a few more tidbits, and can watch [Ed’s] video overview of his home built compressor after the break.

Continue reading “High Pressure Air Compressor Using A Pair Of Refrigeration Compressors” →

Update: McHck’s Self Flashing Rig

September 17, 2013 by 6 Comments

A few weeks ago we featured the McHck project (pronounced McHack), a $5 Cortex M4 based platform which can be directly plugged into one’s computer. Recently, [Simon] announced that he made a firmware allowing a McHck to behave as a SWD adapter and also detailed his flashing rig.

Therefore, those who’d want to build their own McHck would only need to borrow an SWD programmer once to get started. When the first platform has been programmed with the SWD firmware, it can be used to flash and debug applications on the second McHck. Consequently, the microcontroller flashing rig [Simon] designed (shown in the picture above) is based on this. The few core elements are a TQFP48 ZIF programming socket, a push button and two LEDs. Simply push the Kinetis in the programming socket, close it and press the button. Success of the operation is indicated by the two LEDs. [Simon] used the Ragel State Machine Compiler to generate his flashing program and all the code he made can be downloaded from his github.

If you missed the original McHck post now’s your chance to go back and see what it is all about.

Cloning An Infrared Disarming Remote Of A $8 Home Security System

September 15, 2013 by 4 Comments

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[Sylvio] decided to buy one of the cheap alarm systems you can find on the internet to have a look at its insides. The kit he bought was composed of one main motion sensor and two remote controls to arm/disarm it.

Communication between the remotes and the sensor is done by using infrared, requiring a direct line of sight for a signal to be received. Modern alarm systems typically use RF remotes with a typical frequency of 434MHz or 868MHz.  In his write-up, [Sylvio] first tries to replicate the IR signal with one of his ‘learning remote controls’ without success and then proceed to reverse engineering the remote circuit shown in the above picture. Hackaday readers may figure out just by looking at it that it is a simple astable multivibrator (read ‘oscillator’). Its main frequency is 38.5kHz, which is typical for IR applications. Therefore, if one of your neighbours had this ‘security system’ one could just disarm it with any of the same remotes…

[Sylvio] then explains different ways to replicate the simple IR signal, first with an Arduino then with a frequency generator and finally using the USB Infrared Toy from Dangerous Prototypes. We agree with his conclusion: “you get what you pay for”.

Organizing Transistors

September 14, 2013 by 10 Comments

SAMSUNG

Late last year, [matseng] set up an interesting challenge for himself: design a new PCB every week, send it off to a fab house, and build a new project. It’s a grueling endeavor, but some of these projects are actually very useful and cool. One of the best so far is the TraId – a board that identifies a transistor type and pinout with a nice LED interface.

This build was partly inspired by Dangerous Prototypes’ Part Ninja, a board that determines the pinouts and values of transistors, resistors, caps, and diodes. The TraId is a much more cut down version usable only for transistors, displaying the orientation of the pins and type of transistor on a set of 8 LEDs.

Although the design is very sparse, we could imagine something like this being very useful in a hackerspace, lab, or anywhere else the gremlins of chaos come to reorganize parts drawers. If you’d like to build your own, all the required files are up on the gits.