December 2020

Clever Controller for a Dumb Battery Charger

This controller is specially designed for use with basic, low-cost lead-acid battery chargers of the kind commonly sold in auto markets. It upgrades ‘dumb’ chargers to a super-intelligent ones that protect batteries during charging and offer proper charge termination, float charging and temperature compensation. It charges 6V, 12V or 24V flooded lead-acid, sealed lead acid and new-type LiFePO4 batteries at up to 10A, with a suitable charger. Bulk charge, absorption and float charge phases, battery discharge and cold battery charge protection and many more desirable features. PIC 16F88-microcontroller based with source code available free via our Online Shop. Discrete component circuit design.

LFSR Pseudo Random Number Generator

By combining a few basic logic ICs, it’s possible to digitally generate a pseudo-random number sequence that can be utilised in a variety of applications including our Stackable LED Christmas Tree (November issue). This Linear Feedback Shift Register is an interesting project using just a handful of classic CMOS logic chips.

High-Power 45V/8A Variable Linear Supply (Part 3)

This adjustable bench PSU delivers all the power you’ll need for developing or testing projects – the linear supply can deliver up to 8 amps (@16-45V continuous) or up to 50V at lower currents.  The variable voltage, variable current project has low ripple and noise and has a digital display. Inside it uses a 500VA toroidal transformer. In Part 3 we describe the finishing touches, instrument case preparation and final assembly.

Building a Hi-Fi amp on the cheap!

This article is an ensemble of ideas for building your own audio amp using either prebuilt audio modules or salvaged parts. Lots of hints and tips about component selection and assembly are included in an article that will interest audio enthusiasts who enjoy the practical side of building their own equipment.

Also in this issue:

• The Fox Report – more trials and tribulations about smart electric and gas meters that go dumb
• Techno Talk – how an old TV set took out a village broadband service
• Net Work – the rise of MG Cars and the Honda e electric car; trying out a HeimVision IP camera, and more in this month’s column
• Audio Out (Part 2) – constructing and testing the performance of the PE Theremin amplifier – and then improving it!
• Make it with Micromite (Part 23) : Analogue inputs and servos – it’s back to basics this month as, by popular request, we explore methods of interfacing the Micromite with analogue signals. A model servo controller is used as an example application.
• Circuit Surgery – introducing the Micro-Cap 12 simulator, which is now available for download free of charge.
• Max’s Cool Beans – Flashing LEDs and drooling engineers – Max lifts the lid on the ‘drip’ effect code to produce a deluge (nearly) on his NeoPixel-powered ping-pong ball display

In next month’s issue:

Nutube Miniature Valve Stereo Preamplifier; an 8×8 RGB LED matrix controller; a complete Arduino DCC Controller and a Tunable HF Preamplifier with Gain control. Contents may be subject to last-minute change.