YOU'RE WORKING INTO the early hours on your computer sequencer. The song nearing completion is the culmination of many hours of diligent work. Suddenly, the lights dim. Cause: a momentary reduction in the mains power supply. Result: computer crash.
Although we're not normally aware of them, power blips are very common. Sometimes they last for a split-second, sometimes for much longer; either way they can have disastrous consequences for computer users. We're not talking about a power cut, but these happen too and have equally serious consequences.
Another common computer-related problem is noise. An electrically noisy fridge or washing machine can produce clicks and buzzes that can be heard on speakers and can upset a computer.
The solution to all of these problems is to use an Uninterruptible Power Supply (UPS). This sits between the mains and your computer and consists of a mains filter (for removal of mains-borne noise), a heavy-duty battery and a charger. The system works in the same way as a car battery. When the mains is on, the battery is being charged, but should the voltage fall below a predetermined level, the UPS kicks in and takes over the job of the mains supply - keeping your computer working.
Such units have been available for a long time but they have usually been large in size and expensive. Emerson Electric Company have now brought out the Accupower range of UPSs which are aimed specifically to protect computers and their peripherals. They can only handle devices with a low power consumption but have a cost to match - for example, the smallest unit (Model 10) retails at just £153. This will deliver just 90 Watts, but it should be adequate for most computer installations. The power consumption figure stated on the base or rear of most devices is often the maximum possible power that can be supplied by the power supply. For instance, the Atari ST is rated at 120W, but the power required by the two voltage rails is only around 34W. Of course, there is enough power from an Atari power supply to run a second floppy drive (and even an internal hard drive on the Mega series, which has the same power supply) but the figure of 120W is misleading when trying to calculate what power output you need from a UPS.
A typical setup might be something like this: Atari ST (34W), SM125 monitor (33W) and a Supra hard drive (25W). Total power consumption comes to 92W maximum and the overload capacity on the Model 10 would allow for the odd two Watts. Printers tend to consume more power - a dot matrix might be around 140W while a laser printer would be nearer to 1kW, although this is only relevant when the printer is working.
Models 10 and 20 (180W) are both the same physical size - 9cm x 14cm x 38cm (pretty small), and one of these should suit the needs of most computer users. The casing is metal with a high-density ABS (plastic) front and it's finished in pale grey. The controls are minimal - an on/off toggle on the front and an LED to tell you that the unit is on. If the live and neutral of your mains supply happen to be wired the wrong way round, the LED turns amber to warn you. The rear has a socket for input and output respectively and Emerson provide you with a distribution block with either two or four outputs.
When the unit kicks in, it does so with a loud, intermittent buzzing, accompanied by the green LED flashing. In the case of a complete power cut, you then have eight to ten minutes to finish what you're doing and save to disk before shutting down the system safely (actual time depends on the load - you could get substantially more than ten minutes). When the battery is close to being drained, the buzzing becomes continuous.
It's an unnerving experience to set a floppy drive into the motions of saving and to then turn the power off at the wall socket, but that's what I did to check the UPS. I'm happy to report that the unit kicked in immediately without any indication from either monitor or active disk drive that anything was amiss. In fact saving to a hard drive, a far more risky affair, also continued normally under the same conditions. In the course of writing this review, the UPS kicked in once as the lights dimmed - it was momentary, but it would previously have cost me a heartbeat or two.
For the price of a low-end sequencer, I'd have to say that a UPS is essential to anyone who uses their computer seriously.
Prices Model 10 (90W), £153; Model 20 (180W), £271; Model 30 (300W), £340; Model 40 (480W), £511; Model 50 (840W), £764.
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