Electronics Forum

Electronics Circuits & Projects discussion forum. Get help with electronics.

Help on alarm project

New to electronics? Don't know where to start. No problem! Post your questions here.

Moderator: pebe

Help on alarm project

Postby JHB1955 » Thu Nov 26, 2015 3:36 am

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
Posts: 1
Joined: Thu Nov 26, 2015 3:17 am

Re: Help on alarm project

Postby KMoffett » Sat Nov 28, 2015 3:59 pm

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

Posts: 190
Joined: Sun Apr 13, 2014 3:41 pm
Location: Minnesota USA

Re: Help on alarm project

Postby PradeepKumar » Tue Sep 20, 2016 5:29 am

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)
Posts: 48
Joined: Tue Apr 19, 2016 4:48 am
Location: Bangalore

Re: Help on alarm project

Postby Relayer » Tue Sep 20, 2016 9:15 am

it sounds like your wiring may be askew, or possibly something got in and is shorting on the pcb.

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...
Posts: 33
Joined: Sat Sep 12, 2015 12:50 am
Location: Werribee. Australia

Return to Electronics newbies

Who is online

Users browsing this forum: No registered users and 4 guests