• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Siren sound

Not open for further replies.


New Member

Hi all,

Hi all,
I built this siren, sound with those 130 in one Projects, I wired it up and it done the siren raising up the release the key then it goes down.. but the thing Im asking is when the actual siren sound finished, and I continued to listen at the output/(Speaker) there was the same slow rise in pitch and faded away, I timed it and it took 5seconds in all to start then end.. whats happening here please.

Any help would be greatful, its really weird.
the circuit uses a PNP Transistor, and couple of restistors, and a output transformer.. like the LT700 type.. and of course about 3caps+ one being a 100uf electrolitic cap..
hmm Stummped on this one.
thanks in advance
PS the bit above was very low in audio level.


Please post a schematic, we have no idea as to what circuit you've built.


ehhh ehheheheh
101 electronics kit book =) I could spot one of those a mile away.
I think I have that same book, well my stepson does, but I'm the only one of us that uses it =)
Not open for further replies.

Latest threads

EE World Online Articles