September 2010

This month’s highlights

Planet Jupiter Receiver

Try your hand with some basic radio astronomy using our Jupiter Receiver. Listen to bursts of noise originating from the planet Jupiter or maybe the Sun. Our superhet shortwave receiver uses a dipole antenna (also described) and is hooked to your PC sound input or speaker, so you can chart and print any sound events. Uses a surface mount receiver chip.

Ultra Low Distortion 200W power amplifier (Part 2)

A truly exceptional new class-AB design using Thermatrak power transistors for maximum stability and protection. Producing high power levels (200W into 4R, 135W into 8R) at very low distortion (rated <0.008% from 20Hz to 20kHz @ 8 ohm). Input sensitivity 1.26V rms, 12k. Finely-tuned double sided pcb design eliminates unwanted magnetic fields to enhance its terrific performance.

In Part 2 this month we supply all the constructional details plus coil winding and power supply information.

Vehicle Low-Voltage Adjustable Regulator

Need to operate a CD or MP3 player from your car’s cigarette lighter socket? Or other low voltage equipment? This low-voltage adjustable regulator will reduce the vehicle’s supply down to what’s needed. It has jumper shunts to select one of six common voltages from 3V to 15V, and can supply up to 4A current. Suitable for 6V, 12V or 24V input supplies with heatsinking modifications as described.

Balanced/ Unbalanced Converter for audio work

In the audio/ PA arena, balanced lines are used for long signal runs in order to avoid hum or noise pick-up. This Balanced/ Unbalanced Converter can convert a balanced input to an unbalance done, or vice versa. Ideal for e.g. using standard unbalanced audio equipment on balanced inputs etc, or the other way round. Straightforward to build with full constructional details supplied.

Other features this month include:

Circuit Surgery – a complete walk-through of the maths behind Total Harmonic Distortion.
Recycle-It – how to build a low-cost highpower fan cooled 5V / 12V power supply from an old computer PSU.
Ingenuity Unlimited – readers’ prize-winning own circuit ideas
Practical Speaking everything you want to know about building stripboard circuits
Net Work – the Internet column – getting started with Twitter
Max’s Cool Bean’s Blog – Max the Magnificent steampunks his iPod headphones, and embarks on an LED effect “coal-fired” furnace (boiler).