Farewell Economy 7, A Casualty Of The Long Wave Switch-Off

If you paid attention to advertising in 1980s Britain, you were never far from Economy 7. It was the magic way to heat your house for less, using storage heaters which would run at night using cheap electricity, and deliver warmth day-long. Behind it all was an unseen force, a nationwide radio switching signal transmitted using the BBC’s 198 kHz Long Wave service. Now in 2025 the BBC Radio 4 Long Wave service it relies on is to be turned off, rendering thousands of off-peak electricity meters still installed, useless. [Ringway Manchester] is here to tell the tale.

The system was rolled out in the early 1980s, and comprised of a receiver box which sat alongside your regular electricity meter and switched in or out your off-peak circuit. The control signal was phase-modulated onto the carrier, and could convey a series of different energy use programs. 198 kHz had the useful property due to its low frequency of universal coverage, making it the ideal choice. As we’ve reported in the past the main transmitter at Droitwich is to be retired due to unavailability of the high-power vacuum tubes it relies on, so now time’s up for Economy 7 too. The electricity companies are slow on the uptake despite years of warning, so there’s an unseemly rush to replace those old meters with new smart meters. The video is below the break.

The earliest of broadcast bands may be on the way out, but it’s not entirely over. There might even be a new station on the dial for some people.

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The First New Long Wave Radio Station Of This Millennium

The decline of AM broadcast radio is a slow but inexorable process over much of the world, but for regions outside America there’s another parallel story happening a few hundred kilohertz further down the spectrum. The long wave band sits around the 200kHz mark and has traditionally carried national-level programming due to its increased range. Like AM it’s in decline due to competition from FM, digital, and online services, and one by one the stations that once crowded this band are going quiet. In the middle of all this it’s a surprise then to find a new long wave station in the works in the 2020s, bucking all contemporary broadcasting trends. Arctic 252 is based in Finland with programming intended to be heard across the Arctic region and aims to start testing in September.

The hack in this is that it provides an opportunity for some low-frequency DXing, and given the arctic location, it would be extremely interesting to hear how far it reaches over the top of the world into the northern part of North America. The 252KHz frequency is shared with a station in North Africa that may hinder reception for some Europeans, but those with long memories in north-west Europe will find it fairly empty as it has been vacated in that region by the Irish transmitter which used to use it.

So if you have a receiver capable of catching long wave and you think you might be in range, give it a listen. Closer to where this article is being written, long wave stations are being turned off.

Harris & Ewing, photographer, Public domain.

DIY Illuminator For UV Fluorescence Photography

The image shown is the mineral Hackmanite, which fluoresces under ultraviolet lighting. However, not all UV is created equal, and that makes a difference if you’re into UV imaging. The image for this article is from [David Prutchi] and shows the striking results of using different wavelengths of UV. [David] goes into detail on how to make your own DIY Long, Medium, and Short-wave UV Illuminator complete with part numbers and wiring diagram. The device isn’t particularly complicated; the real work was determining the exact part numbers and models of lamp, filters, and ballasts required to get the correct results. [David] has done that work and shared it for anyone interested in serious UV fluorescence photography, along with a white paper on the process.

We’ve seen [David]’s work before. We featured his DIY short-wave UV imager in the past, and his DOLPi camera project was a 2015 Hackaday Prize finalist. It’s clear he really knows his stuff, and genuinely enjoys sharing his discoveries and work.