March 2018

Stationmaster PWM Model Railway Track Controller

This pulse-width modulation (PWM) controller is just the thing for smaller model railway layouts, offering train enthusiasts all the features needed for realistic and stable speed control. It includes a hand-held controller for ‘walk around’ use that can be connected to sockets conveniently located around your layout.

Features include forward & reverse, speed, inertia (momentum) and emergency brake. It has a fully-protected H-bridge motor controller output stage offering up to 3.5A with adjustable current limiter. Discrete circuit design with a very small amount of surface-mount soldering needed.

SC200 Amplifier Module (Part 3)

In this third and final instalment we provide the SC200’s performance details, power supply details plus a suggested initial safe power-up procedure.

Using Cheap Asian electronic Modules (Parts 2 & 3)

We’ve a double bill for readers this month! Firstly we examine the ready-made HR-SR04 ultrasonic distance module, showing how it works and how to use it in various monitoring applications with a Raspberry Pi, Arduino or Micromite.  Secondly this month, a computer interface module based on a serial USB-UART is explored. It allows just about any microcomputer or peripheral module to exchange data with a PC, via a standard USB port. Plenty of practical hints and tips in this article!

Teach-In 2018 – Get Testing!
Part 6: Audio frequency measurement and testing

This in-depth hands-on primer continues with tutorials on the specifications for audio frequency equipment including pre-amps, filters, tone controls and power amplifiers. Many common parameters such as distortion,  hum, crosstalk, frequency response and more are explained along with an overview of test equipment useful for AF-related tasks.

Audio Out

Our column for serious sleeves-up audio circuitry enthusiasts. A single-rail modification for the MX50 amplifier module is described this month.

Electronic Building Blocks

A cheap and cheerful multi-mode flasher module from China is explored.  Available from eBay, it’s useful for high-power LEDs or incandescent loads. Usage considerations are included in this month’s feature.

Also in this issue

• Techno Talk – the impending threat of solar flares
• PIC n MIX – utilising four-digit 7-seg displays (Part 4)
• Net Work – why some websites contain hamburgers!
• Circuit Surgery – system power supply switching and load switch ICs are explained

Next month

Spring Reverberation Unit;  Touchscreen DDS Signal Generator; Upgrade your Arduino Theremin; Teach-In Part 7 – Radio Frequency measurements; Low-Cost Electronics Modules (Part 4): digital temperature and RH sensing module.