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Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to "Ask SILICON CHIP" and "Circuit Notebook".

Candles a considerable
risk to TV sets

Last week was another where I saw a TV with a fresh 50mm disc impression from a candle embedded in the top of its cabinet. The lady who put it there was surprised that the solid looking silver cabinet was actually moulded from highly-flammable High Impact Polystyrene (HIPS) resin. In 1996, State Fair Trading departments, alarmed at a dramatic rise of house fires from modern TVs with flammable cabinets, drew up new regulations in consultation with manufacturers/importers for cabinet flammability.

The manufacturers would not agree
to mandating flame retardant in the front of CRT TV sets, as they feared any price increase would affect sales. Despite these objections, regulations were drawn up to be introduced to coincide with the 1988 C-Tick EMI regulations. These regulations required that the material of the cabinet back of CRT TVs be tested as self-extinguishing for each model on sale.

Concerns were put to the new Liberal federal government that manufacturers needed time to clear stock, so the Howard Government placed a moratorium, until 1 July 2000, on the new regulation, allowing multinational companies to import or dump these sub-standard sets into Australia.

Regardless, these regulations do not stop TVs from catching fire if candles are placed on them or on the rare occasion of a power switch “fusing” or shorting out. I know of no regulations in relation to fire safety of flat panel TVs that also mostly use polystyrene cabinets. It is best not to leave equipment unattended if switched on at the wall and never place candles on top of them.

Tony Backhouse,
Narraweena, NSW.

Comment: candles might be romantic but they are always a fire risk.

Let the buyer beware – salespeople’s advice is suspect

Your Publisher’s Letter on TV sound (July 2010) brought up issues I totally agree with. Fortunately, the TV I purchased does have analog audio out, so I looked for an amplifier for top-quality sound. However, with a budget of just $250 and not much space, it was a tall order. In a leading store, the salesman directed me to a 5.1 system with speakers everywhere and really awful sound.

Legendary brands from the past like Sony and Yamaha were no help either, with one of them quoting full output at 10% distortion! Heck my 1970s amplifier in the lounge has about 0.5% distortion at high volume. So I looked at the bookshelf units and settled on a Panasonic with subwoofer for around $250. It’s brilliant, apart from the bass sounding just a tad “plastic”, due to the heavy plastic speaker boxes.

On CD, with the equaliser set right and a 1950s tune playing, it sounds a lot like the old Astor Concertmaster we had in the family during that era.

It’s important when selecting TVs and amplifiers that we have a check-list of items we need, then use our eyes and ears. Also be sceptical of salespeople’s advice. I went to three stores looking at Panasonic plasma TVs and staff at all three directed me to a recently superseded model, saying it was $200 cheaper but only lacked a couple of sockets.

By the third store, I was absolutely convinced their advice was flawed – the brilliance and contrast was less on the older model – and that indicates it has less reserve for long-term ageing. I paid the extra for the new model. Impulse buyers beware!

Kevin Poulter,
Dingley, Vic.

Solar thermal power stations
have major challenges

Although I’m a keen solar enthusiast, the thermal slant in your informative August 2010 “Solar Power – 24/7” article left me with mixed feelings. Solar thermal may well seem tempting but the article failed to mention that it’s presently facing major challenges (both technical and economic), especially from photovoltaic (PV) systems.

This has largely arisen as a result of the Spanish government’s 2009 slashing of very generous (but biasing) “green energy” subsidies. The resulting sharp reduction in commercial demand meant a global fall in PV prices, making simpler PV-based schemes relatively more attractive, especially when their increasing efficiencies are also considered.

PVs convert sunlight directly to electricity and essentially cease work-
ing after dark – charged battery banks being normally then needed. However, PV-based energy schemes can be immediately and progressively commissioned, with extensions as cir-
cumstances allow. Servicing and upgrading usually can be done without shutting down the entire operation. As PV arrays do not even need to be precisely arranged, irregular terrain or even disconnected sites can be utilised as well.

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