Category - Electronics

Doorbell Light for the Hearing Impaired

Summary: The objective of this project was to create a visual signal on my treadmill to alert me when someone was ringing the doorbell. Why a visual alert? Well, because I invariably have music blaring out of my in-ear headphones when I’m running. Between that and the noisiness of the treadmill itself, I have, in the past, missed the delivery guy knocking at the front door. It is so annoying to have to go on a treasure hunt just to recover parcels that I could have easily received myself if only I had known someone was at the front door. The final device I settled on consisted of a large red flashing LED to get my attention, controlled by a 556 timer chip (which is two 555 timer circuits in one package). I then connected it through internal house wiring to the doorbell. In addition, I designed the enclosure housing this doorbell light to fit into one of the bottle holders on my treadmill's display console.

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Best Digital Multimeter for Electronics Work and for the Electronics Hobbyist

The digital multimeter is one of the most important tools in the electronics professional’s and electronics hobbyist’s toolbox, so much so that electronics aficionados usually have more than one. However, digital multimeters are used not only by electronics enthusiasts but also by other professionals such as car mechanics and electricians, who often have slightly different needs with respect to multimeter specifications. Consequently, the humble digital multimeter comes in a variety of different flavours which cater to the needs of different professions. Therefore, the electronics hobbyist needs to know beforehand what specifications are appropriate for electronics work, and what he or she should be looking for when buying a digital multimeter. So what's the best multimeter for electronics work and what should a newly-minted electronics hobbyist be looking for in their new digital multimeter? Let's try to answer those questions.

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Making a USB Temperature Sensor

Summary: The idea here was to create a temperature sensor that could easily be connected to an Apple Mac computer and have it display its readings inside an OSX application. More a demonstrator than anything someone might actually use in the real world, but who knows, maybe someone out there has a practical need for such a contraption...

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USB Breakout Board for V-USB

Summary: The objective here was to make a USB breakout board that incorporates the hardware required to implement the mostly-software-based USB protocol, V-USB from Objective Development. The completed V-USB module can be connected to a range of Atmel AVR® microprocessors involved in various projects at the breadboard stage, obviating the need for additional USB circuit components to be added separately to the project breadboard whenever USB functionality is required. The use of V-USB where the USB protocol is incorporated into the main project AVR microcontroller also replaces the need for a dedicated chip to handle the USB protocol.

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USART Debugger on the AVR Microprocessor

Summary: When trying to build an electronic device based around a microprocessor, it's useful to have the microprocessor itself send back updates as it executes its code so that one can debug any problems with the device. The microprocessor type that I invariably use is an Atmel 8-bit AVR (most often the ATmega168) so this write-up will be focused on getting that system to work. So how do we get these debugging messages from the AVR microprocessor? One way is to use the USART capabilities of the AVR to communicate with a computer via an RS-232 serial connection. Although the RS-232 serial connection represents an older way of doing things, it does work just as well, for our purposes anyway, as more modern methods, and is especially appropriate if you have an old unused computer lying around that could do with a new reason to live!

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Exploring UHF RFID: Power, Modulation, and Global Standards

Radio Frequency Identification (RFID) technology is increasingly being used to track just about everything. Indeed, applications of the technology include diverse areas ranging from business inventory management to crowd control at large public events. As we delve further into the era of the internet of things, the use of RFID is expected to rise even more. There are a number different types of RFID technologies in use today, differentiated by the electromagnetic frequencies they use and whether their tags are passive or active. One type of RFID tag technology that has been growing in use more recently is that which uses the Ultra High Frequency (UHF) band of the electromagnetic spectrum. The UHF band encompasses radio frequencies from 300 MHz to 1 GHz, but the UHF RFID tags and readers that are making the most waves recently are those that use the 860 MHz - 960 MHz portion of the spectrum. But how exactly do UHF RFID tags work?

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A Simple Programming Board for the AVR microprocessor

Summary: A number of the device creation projects detailed on this website use the Atmel AVR microprocessor as the CPU or the 'brains' behind the device. However, before one can build any of these devices, one has to be able to get the firmware code on the AVR itself. There are a number of ways to achieve this and the method described here is probably not the most efficient way, but it does tend to be one of the less expensive ways of firmware loading and can also put to work some old equipment which you might have lying around earmarked for the trash heap.

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