13 June 2010

This linear bench supply can deliver up to 1.6A from positive and negative outputs with a range of ±0-19V. It has adjustable current limiting for both outputs and can display the voltage or current reading for either rail. If powered from an AC plugpack, no mains wiring is required, although less current is available. It also has a 5V 750mA output for powering digital logic ICs and microcontrollers.

09 June 2010

This Air Quality Monitor indicates carbon dioxide (CO2) and carbon monoxide (CO) levels on a dual bargraph and sounds an alarm when either level reaches a preset concentration. You should use it if you have an unflued heater in your home, boat, caravan or any indoor space.

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.

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%.

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.

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.

13 April 2010

Do you need to measure the EHT voltage in a CRT-based scope, computer monitor or TV receiver, or perhaps in a photocopier, laser printer or microwave oven? You'll need an EHT probe to suit your digital multimeter (DMM) to do this and you'll find they are pretty pricey. Not to worry though, because here's one you can build for less than $40.

09 April 2010

Here's a cut-down version of the Digital Capacitor Leakage Meter we described in December 2009. Instead of using a PIC microcontroller and an LCD panel to display the leakage current, this version connects to your DMM to provide the readout. It provides the same range of seven different standard test voltages (from 10V to 100V) and can measure leakage currents down to 100 nanoamps!