Save money and torch your home.
Added 2018-10-12 01:57:31 +0000 UTCA very cheap smoke detector sold on eBay that does not contain the usual dedicated chip used in many commercial units. This one uses the ubiquitous 8 pin chip, and we may have sussed out what it is.
https://www.youtube.com/watch?v=AOCrG0mOMW4
I'm guessing the main reason for using this particular microcontroller in your products is that it costs 3 cents. And that's in quantities of ten and more! 3 frickin' cents for a full microcontroller with 1K program space, RAM and peripheral modules!!!
Comments
I wouldn't recommend making it quieter. It's loud so it wakes you and your dog if a real fire occurs.
Big Clive
2018-10-30 21:16:43 +0000 UTCI had a false alarm from my smoke alarm the other night, about 3 am. Drove my dog mad with the shrill noise. Was wondering if it is possible to tone it down. I tried inserting a resistor (1m ohm) in series with the centre of contact of the piezo but no effect. Any suggestions?
2018-10-30 16:15:54 +0000 UTCI would like to see the quality of an ionization detector from the same manufacturer.
AESFTW
2018-10-17 14:46:47 +0000 UTCI purchased some of these some time ago expecting they would be similar to the previously dissected models with dedicated controllers. The units I received are similar to this video, but the PCB is about half the size and the piezo buzzer is clipped into the back of the alarm housing rather than being board mounted. It lacks the black plastic horn that yours have and just fires backwards through a grille molded in the housing. It's not very loud at all. The electronics seem indistinguishable from yours. These things eat batteries at an "alarming" rate. A fresh battery has dropped to 7.8v in only three months and while the indicator LED continues to blink normally, if I press the test button, it blinks dimly and the buzzer produces a fast and very quiet warble. As you observed, there seems to be no low battery warning. If the alarm is triggered with the battery in this state, it warbles in the same manner. You wouldn't be able to hear it from another room. I measured quiescent current and my meter fluctuates between 25µA and 100µA about twice per second. When the alarm is triggered or being tested, it's pulling 17mA.
2018-10-13 04:56:18 +0000 UTCThe cheapest model on eBay just randomly lights up every few hours and says, "Does anybody smell smoke...?"
Daddy Bearcat
2018-10-12 17:02:09 +0000 UTCVery interesting circuit discussion. Learned a lot. Mini master classes! Thanks.
2018-10-12 14:18:26 +0000 UTCEevblog just did a video on these chips. Interesting info, but can't hold a candle to Big Clive, of course.
Jeremy Impson
2018-10-12 07:39:28 +0000 UTCCheaper than a 555 timer.
Big Clive
2018-10-12 03:30:58 +0000 UTCDefinitely, "you get what you pay for" great video though...
Richard Boyce
2018-10-12 03:08:06 +0000 UTCthat’s a lot cheaper than an attiny.... neat.
Michael Gilchrest
2018-10-12 03:02:18 +0000 UTC3 cent full micro controller DAM ..? HOW ? 3 cent full micro controller
God 420
2018-10-12 02:31:03 +0000 UTCThe old rule of "caveat emptor" and "you get what you pay for"
Dustin
2018-10-12 02:19:27 +0000 UTC
