June 2014

Cranial Electrical Stimulation

Cranial Electrical Stimulation (CES) involves passing a very small amount of current through the recipient’s head. A proportion of this is thought to pass through the brain where it can create chemical changes that can influence one’s mood. Some users of cranial electrical stimulation devices claim they reduce anxiety, helps treat pains (especially headaches) and promotes alertness and relaxation.

We make no claims of the benefits of our CES design but commercial units can cost hundreds of pounds, so ours is safe, cheap and easy to build and experiment with. It uses 4000-series CMOS logic devices, is battery powered, portable and has adjustable current delivery (0.03-0.5mA) and repetition rates (0.5 – 100 Hz in four steps) with a 15V limited output. A flashing activity LED and automatic countdown timer are included along with details of suggested DIY earlobe probes.

 This unit (and any other similar device) may not be used by persons who have a heart pacemaker or any other such implanted device.

Must be powered by batteries only. Not to be operated using a mains adaptor under any circumstances.

Mini Audio Mixer

This rugged and portable audio mixer was designed for on-the-road use, useful perhaps for times where access to a venue’s existing PA system is restricted or you want to add a mixer onto a mobile PA setup quickly and easily.

The versatile mixer can simply be inserted between an XLR mic lead and the microphone and effectively gives a straight-through connection that does not affect the operation of the PA itself. It also provides various Line Input sockets and level controls. Optional built-in 3.7V Lithium Ion battery and charger. An ideal answer to mobile PA frustrations and a handy module to keep in the PA toolkit when you’re on the road.

Bits ‘n Pieces Battery Charger Digital Voltage and Current Meters

Last month we offered a ‘Bits ‘n Pieces’ Car Battery Charger made from surplus mains transformers at the lowest possible cost.  This month we add digital volt and ammeters to complement the charger circuitry. A great project for experimenters or for re-purposing some suitable surplus parts.

Teach-In 2014 Raspberry Pi (Part 9)

The penultimate part of our Raspberry Pi tutorial series features this month the construction of an infrared (IR) camera with an integrated light source that’s ideal for wildlife monitoring, simple home security applications or general low light-level photography. Source codes can be downloaded for convenience and there’s a fun quiz too. If you’re keen on the Raspberry Pi, Teach-In 2014 is for you.

Also in this month’s issue:

• Max’s Cool Beans – Max the Magnificent proceeds further with his Kickstarted (we hoped!) Universal Screw-block Proto-Shield.
• PIC ‘n MIX – this month we complete the ‘port’ of the development board template from assembly language to ‘C’. Source codes downloadable from the Library.
• Interface – the page for PC interfacing enthusiasts  looks at IO multiplier techniques.
• Circuit Surgery – our in-house ‘surgeon’ digs deeply into the topic of state-variable filters.
• Net Work – the Internet column offers surfing options for Windows XP users, and describes a home NAS upgrade using NAS-Enterprise-ready hard disks from Western Digital.