Smoke alarms come in various guises these days,whilst not a total list the
following may help.
Firstly your post says "Smoke" alarm.As such two main types are easy to
obtain Optical or Ionisation.
Mainly people tend to adopt the Optical sensors but both detect the presence
of smoke in the case of fire.
These can be a pain in a kitchen and normally a temperature rise device or
Heat detector is employed.
Next is the power supply for the device.
Mains powered units are preferred and most have a built in rechargeable
battery in case of mains failure.
Failing this battery only devices are available from a simple 9v PP3 to a
5yr lithium battery.
If fitting more than one device a linked system is useful ;not to be
confused with a fire alarm system these devices have linked cabling and each
device will repeat the activation of any devices on the link.
Like everything these days you get what you pay for so the more the sensor
has to offer the dearer it will be.
Google smoke detectors for 1000's of options and pictures but check the
Spec' before buying.
"cryptogram" wrote in message
Anyone familiar with these? I need to replace mine and I'm hearing that
there are at least two types. If I'm going to buy something I might as well
go for something that will cover all evetualities - not just burnt toast.