22 May 2010

In the March and April 2010 issues, we described the design and construction of our new Digital Audio Signal Generator. The final article this month has the driving instructions.

18 May 2010

Looking for an efficient USB charger that can operate from a 12V car battery? This unit functions at up to 89% efficiency and can charge USB devices at currents up to 525mA. Best of all, it won’t flatten the battery if it's left permanently connected, as long as you remember to unplug the USB device.

14 May 2010

This bench-top multimeter features 6½ digit readings, a graphic LCD and a number of advanced features such as trend plot, histogram and dual measurement mode. With front and rear panel inputs, its short term and 1-year accuracy figures are outstanding.

10 May 2010

Amplifiers which run from 12V DC generally don’t put out much power and they are usually not hifi as well. But this little stereo amplifier ticks the power and low distortion boxes. With a 14.4V supply, it will deliver 20 watts per channel into 4-ohm loads at clipping while harmonic distortion at lower power levels is typically less than 0.03%.

08 May 2010

Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates.

06 May 2010

The TDA7377 IC from ST Microelectronics is the main component of this month's 12V Mini Stereo Amplifier. It's not a new chip – they've been making them since at least 1998 - but it is the first time we've used it so it deserves some elaboration. It comes in a 15-pin "Multiwatt" package similar to TO-218 and is available in both horizontal and vertical mounting packages.

04 May 2010

Need lighting away from a power source? Try this one: it's ideal for your garden, shed or even a camp site. With a 5W solar panel, a 12V SLA battery and a smart controller, it has 3-stage charging for the battery and Maximum Power Point Tracking (MPPT) for the solar panel.

02 May 2010

Most offices, factories and shops waste a lot of money in power for lighting. How would you like to save up to 50% of your lighting power bill . . . and get even more light into the bargain? We show you how - and have the measurements to back it up!

23 April 2010

Last month, we described how the S/PDIF Digital Audio Signal Generator works. This month, we describe how to assemble the PC boards, mount them in the case and check that they are working correctly.

19 April 2010

Want to control something - anything - with commands from your PC? Perhaps turn sprinklers on and off to water your garden? Maybe read some sensors? Or even sequencing Christmas tree lights in time with music? (OK, so we're getting in early!) Making the computer output the correct information is one thing. Interfacing that data to control real-word devices is another. That's what this nifty little relay box is all about.