Quote Originally Posted by BobK View Post
Hi Maxster03,

I have made an assumption that you are using a battery operated smoke alarm. We in the alarm profession call a 110vac or battery operated detector a smoke alarm. One that is made for alarm systems integration (wired in) is called a smoke detector.

Anyhow, I am currently out of town and do not have drawing capabilities. As soon as I get back to my computer I will make a drawing for you. It really is quite simple though. Do you know what an optoisolator is? Do you have access to a store like Radio Shack? They sell a few different types of them. I don't know where you are located.

Take the voltage readings with a voltmeter. A scope is overkill but if you have that and no voltmeter then that will do.

Do you know who the manufacturer is?

I'll check back with you this evening. I'm in Ohio on the Eastern time zone.

BobK
yeah i am using a Battery Operated Smoke Detector, Its a 9V Battery. Well i am Currently located in Bradford, England. but i think i can get a Opto isolator from here. Well the smoke detector is quite a cheap one, the company is Ei Electronics, basically i am doing a project on home alarm system in the university, well i have measured the voltages with both voltmeter and the scope, i have already mentioned the scope readings, it gives me the following readings with the digital voltmeter but they are changing all the time

red/black = 0.70V to 0.80V (not constant)
red/ white = 2.20V to 2.50V (not constant)

Well i have heard about the Opto isolator but i am familiar how it works and its functions.

Thank you so much for your help, i would be looking forward for the drawings