T.K. Hareendran writes:
All items stored in a deep freezer will thaw out if, for some reason, the temperature inside the freezer rises to the thaw point. However, a freezer monitor alarm can warn you of the rising temperature before the thaw point is reached.
This simple circuit is powered by regulated 9V and built around a few discrete components that are readily available in the market. Current consumption of the circuit is only a few milliamperes in idle state. So you can also use a 9V 6F22/PP3 type compact battery for powering the circuit.
Freezer Monitor Alarm - [Link]
I’ve been an electronics hobbyist for many years, so I’ve used and even built my share of resistance decade boxes. Each one consisted of rotary switches with labels identifying a different power of 10 for each switch. You “dialed up” the desired resistance by turning the appropriate knobs to add up to the target resistance value.
Well, I’m also a computer geek, so I got the crazy idea to build a decade box using DIP switches (instead of rotary switches) and binary values (instead of decimal values). Each switch represents a power of 2 and the resulting resistance equals the combined value of the “ON” switches.
Binary Resistance Decade Box - [Link]
What was technology like inside a 1994 Motorola MicroTAC GSM mobile phone?
EEVBlog #492 – Vintage Motorola MicroTAC Mobile Phone Teardown - [Link]
UV resin based mUVe 3D Printer releases source files:
The mUVe 1 3D Printer, an open UV resin based 3D printer was successfully funded on indiegogo back in April. As estimated, the first Ultimate kit was shipped out on Jun.20. Last weekend the team has completed building and shipping all of the Ultimate kits. Meanwhile Dean Piper, the maker behind the mUVe 1 3D Printer project, has shared all of the source material on their website
UV resin based mUVe 1 3D Printer source files released - [Link]
Mats continues his challenge of designing one PCB every week. In week 12 he came up with BB Prince, a small multi-purpose utility for your solderless breadboard:
This PAW is a small utility board for your breadboard that have some of the most common things you need when building a microcontroller-based project on the breadboard. It’s a small (2.5×1.5cm / 1×0.6”) PCB with a Power Led, a Reset button with a pullup and goes low when pressed, a Signal button with pulldown that goed high when pressed and two general Indicator Leds that are connected to ground via resistors.
BB Prince – breadboard utility PCB - [Link]
Boris Landoni writes:
It’s small but packed with features. The GSM alarm we present today, sports a PIR motion sensor, can be battery operated and it’s capable to communicate via GSM. It can transmit alarm conditions and receive commands from remote. It’s also capable to indicate problems such as is insufficient voltage supply or tampering.
It’s not so conventional for antitheft system: to integrate a movement sensor, a PIR motion sensor and a temperature probe in a single appliance: all this accompanied by an SMS sending GSM / GPRS module. This circuit was born as a very versatile, ready to use, built-in alarm system: no installation is required, you can just drop it and it’s ready to work. It’s not by chance that is designed to be battery operated: it also features a battery state control to check the power.
GSM Multifuction Alarm with SIM900 - [Link]
patrick @ plainlystated.com writes:
I bought an antique telegraph sounder a while back, and I’ve been working on a project that will click out emails from my Etsy store when I get an order. I’ve gone through several generations, and come up with something I really like. What follows is a description of my process for going from concept to finished piece. The code & PCB are open-source, and can be found on my github.
Generation 1 – Paper
The end goal I had in mind was to be able to push messages over the network, and have the telegraph sounder tap them out in morse code …
Concept to Finished Piece – Generations of an Electronics Project - [Link]
iFixit dives into their 5th Gen iPod Touch 16 GB teardown with the usual gusto–here are excerpts.
Teardown: 5th-gen Apple iPod Touch - [Link]
Asgard build this Rapper project:
What this is, is a small device that records a command sequence for a TV remote control, then emits the same sequence when activated by a pulse detected in a piezo transducer. Such pulse can be as simple as rapping your knuckles on the table where the Rapper is placed. Typically the Rapper would record the mute control for the TV, so that you can run to get the phone without having to hunt down the remote control for the TV. Cute, eh?
Rapper project - [Link]