What are these components? What do they do?

[joerow]

Hi

I'm very new to electronics having only just gotten into over the Christmas period. I know a little bit of basic electronics and most of the standard components but I'm new to tinkering.

Today I took apart some old window alarms the kind that have one piece affixed to the window glass then another fixed to the window frame. I've figured they are controlled by a magnet so when they are separated the alarm goes off.

When I opened it up to have a look at the board inside there were a few components I didn't recognise.

I have no idea what this one is. Any guesses?
**broken link removed**

I figured this must be the part which makes the sound but I've never seen anything like it either. Do you know what it's called?
**broken link removed**

Thanks for your help.

Joe

 

[DerStrom8]

Welcome to Electro-Tech!

The first one is a magnetic reed switch. When a magnet gets near the reed switch it closes (or opens, depending on the circuit). This is what makes the circuit sensitive to magnetism. The second component looks like a piezo transducer, which is likely used for the alarm. It would work as a sort of speaker to make the sound.
Hope this helps!
Der Strom

 

[joerow]

Brilliant! Thanks for the speedy response.

Joe

 

[DerStrom8]

Not a problem Always happy to help someone out
Der Strom

 

[tom_pay]

Hi

They are really good pictures!!

Have fun tinkering.

Tom

PS Don't be like me, keep the smoke in the component, don't let it out!! A very important tip.

 

[cowana]

The second is a piezo transducer.

As well as being used to convert voltage to vibration (sound), it can also be used to create voltage from voltage. So in an alarm, it could also be used as a vibration sensor.

Andrew

 

[DerStrom8]

The second is a piezo transducer.

As well as being used to convert voltage to vibration (sound), it can also be used to create voltage from voltage. So in an alarm, it could also be used as a vibration sensor.

Andrew

Don't you mean create voltage from vibration?
I'm assuming that in this particular alarm it is only used for sound, though, because the reed switch is what triggers the alarm.
Der Strom

 

[cowana]

Bleurgh - yes, I meant voltage from vibration.

Thanks.