February 2018

This month’s highlights

GPS Synchronised Analogue Clock Driver

Turn your ‘traditional’ quartz stepper-motor analogue clock into an accurate self-adjusting one using this GPS powered module. Regular readers might recall our GPS-Synchronised Analog Clock (March 2011 issue) intended for clocks with stepped hands. This revised unit also works with sweep movements and with a variety of GPS modules, including low cost types, to offer automatic correction for Daylight Saving Time (stepped second hand clocks only).

It’s small enough to fit onto the back of most clocks. PIC microcontroller powered, .hex files for stepper and sweep motors are downloadable free from our web site.

High Power DC Motor Speed Controller (Part 2)

We continue with the constructional, interwiring and setup details of our 60V DC / 40A (max.) speed controller suitable for a wide range of applications, including buggies, transport and mobile equipment or motorised platforms or servo systems. Just the thing for a powerful mobile robot buggy or similar.

Teach-In 2018 – Get Testing!
Part 5: Inductors, resonant circuits and quartz crystals

Our series devoted to choosing and using test gear investigates the theory behind inductors (coils), measuring inductance and impedance and offers a handy crystal checker as a simple project. If you’re a novice or student in electronics, this special series will show you how to handle a multimeter with confidence and interpret the test results.

SC200 Amplifier Module (Part 2)

Last month we introduced readers to the SC200 Amplifier Module, a fantastic new 200W / 4 ohm module offering 0.001% distortion. We described the circuitry, gave a Parts List [see Please Take Note below] and we outlined the optional clip detection circuitry.

In Part Two this month, constructional details of the main circuit boards are provided. In Part Three to follow next month, full performance graphs and the power supply construction will be published. If you want to build a high-performance, high power audio amplifier, check out the SC200!

Please Take Note – SC200 Components List
At the time of writing the FJA4313OTA is available from Digi-Key or as part of a set of hard-to-get parts from the SILICON CHIP Online Shop.

The transformer specification should be 40-0-40 not 45-0-45V.

LED1 is supplied with around 2mA so any blue LED of that size should be fine. The forward voltage is not important as the circuit will automatically adjust to compensate (it’s supplied from a constant current source). – Nicholas Vinen

Max’s Cool Beans Blog – An adieu

Our hero contributor Clive (Max) Maxfield bids readers farewell in his last Cool Beans Blog for now.

Also in this issue:

Techno Talk – the resurgence of Plessey
Net Work – Amazon’s Echo 2nd generation gets the Christmas must-have treatment; Chat Zone news
PIC n MIX – Four-digit 7-segment LED Displays – using a 4×45 keypad
Circuit Surgery – Potential dividers and power supplies
Audio Out – the implications of output capacitors on audio amp performance.

Next month

“Stationmaster” model railway controller offering precision walkaround control via multiple sockets dotted around your layout; SC200 audio amplifier (Part 3); Low-Cost Electronics Modules (Parts 2 and 3); Teach-In 2018 (Part 6): audio frequency testing and measuring.