February 2023

Tesla Coil Solid-State Flame Discharge

You might have seen those spark discharge special effects in horror movies, but this project weighs in at the other end of the scale – it’s a relatively small and simple device that generates extremely high voltages (150kV+) sufficient to form a ‘flame discharge’ resembling a candle flame. A solid-state oscillator drives a Tesla coil that creates a high voltage electrical discharge to produce a plasma flame.

It is suitable for building by experienced constructors only. The published article contains safety and usage warnings which must be clearly understood and observed. This circuit produces extremely high voltages (150kV) and operates at about 10MHz. Not to be used in the proximity of radio transmitters or receivers, especially those operating on SW, 40m amateur radio bands, aviation and maritime or CB radio. Not to be used near heart pacemakers or any other medical equipment.

Cooling Fan Controller and Loudspeaker Protector

This board controls up to three cooling fans, switching them on at a set-point temperature and ramping their speed as it increases, preventing overheating while minimising noise. It can also be used to safeguard loudspeakers against switch-on thumps or over-temperature. Ideal for any apparatus that uses multiple 4-pin PWM cooling fans. Discrete through-hole board is straightforward to assemble. PIC microcontrolled with source code available from our online shop.

Driveway Gate Remote Control

This is a very robust replacement for typical sliding/ swinging electric gate controllers that are prone to fail after a year or two. It uses 74 TTL through-hole components throughout and offers 24VDC or rectified AC output up to 8.33W (200W). Triggered by a separate single remote control or local button, and it halts the gate if an obstacle is encountered. A very thoroughly-designed project that will prove repairable if needed and is therefore future-proof!

Geekcreit’s LTDZ V5.0 Spectrum Analyser

We investigate a low-cost compact unit that can perform spectral analysis from 35MHz to 4.4GHz. It also includes a tracking generator for frequency-domain analysis of filters, RF amplifiers and similar apparatus.  It needs to be controlled from a board via a USB cable, using a very impressive free application.

Also in this issue:

• Techno Talk – how fungi could be harvested in the manufacture of printed circuit board substrates, and how battery-less energy-harvesting applications are taking shape, in Mark Nelson’s penultimate Tech Talk column for Practical Electronics.
• The Fox Report – the enforcement of British TV licence law comes under scrutiny
• Net Work – Failed technologies re-visited, space news, hydrogen-fuelled trucks and electric 4x4s launched
• Kick Start – Part 11: Sensing the environment – introducing the BME280 humidity, atmospheric pressure and temperature sensor
• Make it with Micromite Part 44: a PicoMite Fingerprint reader (Part 2)
• Circuit Surgery – Electronically-controlled resistance (Part 6)
• Max’s Cool Beans – Arduino Boot Camp (Part 2) – how to utilise LEDs and 7-segment displays

Next month:

Amplifier Clipping Indicator; Capacitive Discharge Welder; Model Railway Semaphore Signal; Raspberry Pi Pico backpack. Contents may be subject to change.