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Post by Dave on Jul 13, 2014 11:05:16 GMT
Discussion of safety is a little misleading. Life is all about risk: if you don't take risk, you die; if you don't manage risk well, you die. Spot on  |
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Post by guy on Jul 13, 2014 11:14:18 GMT
The safety issue is a sidetrack/spoiler (put about by people with a vested interest in LDR passives IMO).
The original point raised (long ago on AOS) was the questionable legality of importation of LDR devices in to EU counties.
By the way, could I ask that if people want to copy and paste long extracts from internet sites they at least do the decent thing and provide a reference list/bibliography so that anyone who so desires can look for themselves to see how the pasted information has been selected.
(coursework demand for GCSE Science - you would limit yourself to E/F grade equivalent for not showing how "facts" had been selected)
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Post by lurcher on Jul 13, 2014 12:52:57 GMT
Phil, I understand where you're coming from. It does seem a bit daft that the use of LDRs in a volume control might threaten human survival, but there is a flaw in your argument. Yes, you can fool around all day with high voltages, and if you stick your finger in the wrong place and expire, then I'm not affected except insofar as I lose a friend and mentor. If however the bloke who does the house clearance after you departure decides that your experimental LDR volume control PCB is a load of old rubbish and chucks it on the local tip, that cadmium leaks into the local environment and ends up contaminating MY courgettes. Just because the world is full of old NiCads etc doesn't mean we shouldn't be trying to do something about it! Yep, thats exactly the point. No one is stopping YOU from making a high voltage amplifier and YOU killing yourself with it. However the rules are designed to stop a Chinese (sorry about the stereotype) company from making an amplifier that does the same thing. However because EU law cant stop the Chinese maker from making a dangerous amplifier what it can do is stop (or hold accountable) the importer of that amplifier into the EU region. That amplifier may contain a 500v-0-500v transformer, and while that transformer could kill someone, its not intended to be used by a end user directly, so that can be imported and sold, and its the responsibility of the party that makes that transformer part of a finished product to ensure its used in such a way as to ensure safety. In just the same way, YOU can build a preamp with a LDR in it, and Farnell can sell you the LDR to put in that preamp. What is at this point unsure is if a distributor can import a assembled preamp containing an LDR. The difference between the transformer and the LDR is that the transformer can be constructed containing none of the materials that are potentially hazardous after they are disposed of. Where possible regulations are designed to prevent the use of certain metals in construction. The important part is "where possible". You can't make a lead acid battery without lead, and you cant make a ni-cad battery without Cadmium. Because its hard to replace a lead acid battery in some situation with any other type, there is a exception made for them. There are good alternatives to ni-cad batteries, so they are no longer available from most places. And if someone tried to import a cheap toy containing them, they will be liable to be prosecuted for that. What is unclear is the "where possible" state of LDR's. There was already a exception made specifically for them in the past no one seems to know what the current situation is. Using words like illegal and dangerous IMHO is just News of the World type headlines. |
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Post by MartinT on Jul 13, 2014 15:03:38 GMT
I think we've had quite enough discussion of these devices in different threads now.
Pre65, I would be grateful (and so would most of the membership) if you would limit the size of your typeface please except for sections which you deliberately want to emphasise. Thanks.
Thread locked.
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Post by MikeMusic on Jul 14, 2014 12:44:26 GMT
Well there's another one that's not safe - long posts in large text. And you've not even left the house.  |
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