Inside a proper optical smoke detector
Added 2021-11-22 03:27:07 +0000 UTCThere are strong similarities between the real smoke detectors and the very dodgy eBay ones. Notably the standard sensing chamber. But the ones from your local supermarket have very different circuitry.
https://www.youtube.com/watch?v=9VHUodFkeuU
I'd guess the cheap (not that much cheaper) grey imports from eBay based on microcontrollers are just doing the minimum to pass themselves off as detectors. Some of them are extraordinarily quiet and some just don't detect smoke at all.
Comments
Do smoke detectors expire the UK/EU?
Philip Childs
2021-11-29 00:38:23 +0000 UTC"His moist bug feet" lol I love the random things you say sometimes!
Matt Larson
2021-11-23 01:26:49 +0000 UTCThat transmit circuit is like an IrDA transmitter. You get a nice high current pulse from the cap but no lumpy supply current. The RX strobe is a neat idea to save battery. All photodiodes can be used in forward mode in which case they are generators - no biassing needed. The response is log not linear. Can be useful.
Mike Page
2021-11-22 22:08:13 +0000 UTCWhat a great suggestion L i'd be up for that , O! ya and a bottle of fizzy wine 🤣
2021-11-22 21:53:54 +0000 UTCClive you could sell anything on doorsteps! I bet there's a few hundred of these just been bought and now undergoing dissection. Maybe you could get us all to buy a specific product in advance and tell us what tools to have handy, and then we can all have a livestream step-by-step teardown with you! My suggestion for the first one: a car key fob. Tools: one copper hammer.
Ymir the Frost Giant
2021-11-22 17:32:39 +0000 UTCGood on your fire brigade! It's good to hear they are looking out for your fire safety.
Jeff Huyler
2021-11-22 15:13:24 +0000 UTCThe matches are called smoke matches, they use one when they test our gas fire. You can buy smoke in a can for testing detectors, though that is normally for permanent installations.
Namirred
2021-11-22 12:44:33 +0000 UTCWe have a near 30-year old ionisation smoke alarm in our hallway. We're surprised how sensitive it remains, e.g. a smoking frying pan or toaster will trigger yet, but not set off the recently installed optical alarm (bought locally) in the utility room no further from the cooker. I also remember back in the 90s there being a product sold that resembled matches, but just smouldered a few seconds to either test a smoke alarm or a fireplace chimney for draw.
Seán Byrne
2021-11-22 11:54:09 +0000 UTCBecause I am disabled the fire brigade came an installed some high quality smoke alarms in my house. They told me the batteries should last 9 years.
Jeremy Travis
2021-11-22 10:17:30 +0000 UTC😃😃
2021-11-22 05:30:58 +0000 UTCThat type of diode reverse polarity protection is used in almost every single guitar pedal ever made. Electrosmash has a few different pedal schematics https://www.electrosmash.com/proco-rat#link2 https://www.electrosmash.com/tube-screamer-analysis#power
Loscha
2021-11-22 03:41:53 +0000 UTC
