October 2014

SiDRADIO (Part 1)

SiDRADIO stands for Software-Integrated and Defined Radio – a low cost communications receiver covering 100kHz to over 2GHz.  It houses a USB DVB-T dongle plus circuitry for an upconverter and RF preselector, and is powered from your PC or laptop’s USB port which also runs the application software (we suggest SDR# from http://www.sdrsharp.com).

Full schematic and constructional details of SiDRADIO are offered, starting this month with most of the circuitry and assembly information.

Please Take Note – SiDRadio

The dimensions of the panels in the parts list were incorrect. They should be 219 x 34.5mm.

Hi-Fi Stereo Headphone Amplifier (Part 1)

If you can’t afford – or don’t want to buy – a high-performance amplifier and speakers, you can still have the best possible Hi-Fi sound by building this headphone amplifier and using a set of high-quality headphones.

Our new headphone amplifier will also drive 8-ohm loudspeakers and has a music power of 4.25W for both channels driven. This is more than adequate if you have reasonably efficient loudspeakers in your home, study or bedroom. It is powered from a plugpack and built into a half-size 1U steel case. A high quality design incorporating 26 transistors and 3 dual low-noise op.amps.

Circuitry is described this month and construction and setting up will follow in Part Two next month.

“Tiny-Tim” Horn-Loaded Speaker System

You won’t believe how good these speakers sound, and your friends won’t believe you built them, either! This low-cost speaker uses a single 4” driver and a special rear-loaded horn design to give surprisingly good bass and treble response. It is quite efficient and only needs a low power amplifier to give excellent sound levels.

We think these are better than anything we’ve recently heard at anything like the price. Driver options and full wood cutting diagrams are offered in complete detail and if you can’t handle the woodwork then a local cabinet maker may be able to cut it for you.

We strongly recommend a 15mm veneered plywood. Tiny Tim is a fantastic way to enhance your practical assembly skills so if you’re an audio enthusiast be sure to check out this interesting ‘take’ on speaker construction.

PIC n’ MIX

Having whetted your appetite for a colour graphics LCD display (see August issue), it’s time to hook one up to our development board and have some fun! Our PIC expert explains how to add SPI bus communication capability to our template board source code, and then we show it off by driving a cheap graphics LCD display.

Also in this issue:

• Techno Talk – electricity generation utilities ponder the future of power, whether it’s AC or DC.  And details of a new printer font deliberately designed to save ink and toner, if not the world.
• Make Your Own PCBs (Part 2) – installing and using the recommended PCB CAD software, EagleCAD, to design your own boards.
• Net Work – the Internet column – more on the connected home and a look at Nest Learning Thermostat and Protect smoke and CO alarm.
• Interface – simple Raspberry Pi hardware and software for timing and counting applications
• Audio Out – our audio super-expert continues his quest to eradicate ‘wet’ electrolytic capacitors from audio circuits.
• Circuit Surgery – the essential basics of linear power supply design are explained by our in-house surgeon.
• Max’s Cool Beans – Max marches on with some waterjet-cut fittings for his latest Prognostication Engine(s).