Help on alarm project

[JHB1955]

I have a wireless door bell that puts out a 3 sec, 5 volt pulse and I need it to open a normally closed loop on my 2gig alarm panel. Can this be done using a npn transistor and if so can you recommend the right one to use

[KMoffett]

Not sure how much current your doorbell will supply, but for isolation I would look at a 5V normally-closed reed relay.

Ken

[PradeepKumar]

While you can usually use voltage regulators, it sounds like your wiring may be askew, or possibly something got in and is shorting on the pcb. There isn't really much reason the bell should burn out. All you're doing in drawing power *from* it for the relay. In any case, you may want to have a look at optical isolators. Essentially an led, ldr, and (sometimes) transistor in an IC. They ensure complete electrical separation of the two circuits. You can buy them anywhere, or if you like, salvage them from lots of things (check out transformers, computer PSU's and the like)

[Relayer]

[quote]it sounds like your wiring may be askew, or possibly something got in and is shorting on the pcb.[/quote]
Where in the original posters post does he mention he has a fault?
Either you didn't read his post properly or you're just throwing in bullshit to make yourself look intelligent.
Seems you failed on both counts.
Instead of helping out what-so-ever, you make it all complicated with all your rhetoric drivel...
Relayer