CdS photocell in a biscuit tin - Page 1
Forum section: electronics / general

author: fcb
author_rank: Super Contributor
timestamp: December 20, 2017, 10:35:46 pm
content: Picked up a tin of biscuits from Sainsbury’s supermarket today.It has a voice record/playback feature - triggered by a CdS photocell built into the lid.There’s the non-recycling logo and a warning about not eating the button cell, but no RoHS or CE marking.Am I right in thinking that CdS photocells are incompatible with RoHS/CE/WEEE??

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 20, 2017, 11:19:36 pm
content: CdS cells did not get an exemption, I suppose on account of alternatives being better anyway (silicon or photodiode detectors).Tim

author: rrinker
author_rank: Super Contributor
timestamp: December 22, 2017, 03:38:30 am
content: Funny, I just happened to watch Techmoan's NUC video last night and heard the chime when he opened the box. Hadn't seen that before - I ALMOST went with one for my workbench computer because I wanted small to save as much space as possible, but I ended up building a mini-ITX cube because it was significantly less expensive. ANd I can put it under, if I need to, but it's pushed back in the mostly unusable corner anyway.

author: Halcyon
author_rank: Unknown
timestamp: December 22, 2017, 07:02:32 am
content: Quote from: blueskull on December 20, 2017, 11:27:41 pmAww ripped off! Mine was just a boring cardboard box! It's about a year old however.

author: Ampera
author_rank: Super Contributor
timestamp: December 22, 2017, 07:04:28 am
content: are the biscuits any good though?

author: jonovid
author_rank: Super Contributor
timestamp: December 22, 2017, 07:15:00 am
content: aliexpress has this .just the thing for toys or door bell ....esc

author: Zero999
author_rank: Super Contributor
timestamp: December 22, 2017, 09:09:26 am
content: Quote from: fcb on December 20, 2017, 10:35:46 pmDo you have any pictures?Are you sure it's a CdS cell?Perhaps it's so small, compared to the mass of box, it passes RoHS?

author: fcb
author_rank: Super Contributor
timestamp: December 22, 2017, 01:59:45 pm
content: Quote from: Hero999 on December 22, 2017, 09:09:26 amhttps://www.sainsburys.co.uk/shop/gb/groceries/sainsburys-cookie-envelope-christmas-tin--taste-the-difference-400gI'll take some pix tonight, and strip down the electronics.It looks very much like a CdS photocell, so I'm fully expecting it to be one.A number of years ago I wanted to go into production with a musical instrument product that used 8 photocells - couldn't use photo-diodes, they had to be photo-resistors. I did loads of research into them to try and find a RoHS compliant - I looked at using the Cd weight vs. the overall weight of the product, but that apparently doesn't stand (if my memory serves) - something to do with a CdS cell not being homogeneous material.There were some exemptions made for a number of years for the audio industry (vactrols, used in level control), but these have stopped I believe:http://rohs.exemptions.oeko.info/fileadmin/user_upload/RoHS_IV/Cons_1/Excerpt_report_2007_request_1.pdfSilonex are now:http://lunainc.com, and they still sell vactrols "optocouplers", but no mention of RoHS compliance.

author: Zero999
author_rank: Super Contributor
timestamp: December 22, 2017, 09:17:55 pm
content: If it's a CdS cell, then it's probably not RoSH compliant.Have you tested the recoding and playback? It's had mixed reviews, according to the Sainsbury's website.Just out of curiosity, why did you need CdS cells, rather than photodiodes? I didn't find Marshell's argument for CdS cells very convincing. They mention things such as 64-bit DSP, which is boarding on audiophoolery and their comment about weight and power consumption is a joke, when replacing heavy, power hungry valves and massive transformers, with DSP would reap huge savings in mass and energy. There are plenty of decent, low power, analogue based, automatic gain control ICs available. I think they're resistant to change, like many audio equipment designers.