Smoke detection alarm device

Details Smoke detection alarm device Smoke detection alarm device

1975-09-16

1977-07-26

Caldwell, John W.

Communications: electrical

Systems

Call station

250381, G08B 1710

Patent

active

040386490

ABSTRACT:
An ac powered smoke detector utilizes an ionization chamber as the sensing element and a threshold circuit including a programmable unijunction transistor for activating an annunciator device such as a horn. An ac-to-dc converter provides regulated dc power to the chamber, the threshold circuitry and the annunciator for operation. When a specified level of smoke exists within the chamber, the programmable unijunction transistor is placed in the conductive state and produces a non-latching activating signal which energizes the horn. To insure that the programmable unijunction transistor makes a positive transition into the conductive state at the threshold level, the anode-cathode circuit of the transistor and the transistor itself are jointly selected to provide an anode current greater than the characteristic valley current of the transistor when the threshold level is reached.

REFERENCES:
patent: 3521263 (1970-07-01), Lampart et al.
patent: 3676680 (1972-07-01), Scheidweiler et al.
patent: 3728706 (1973-04-01), Tipton et al.
patent: 3753258 (1973-08-01), Honda
patent: 3922655 (1975-11-01), Lecuyer

Affiliated with

Also associated with

Rating

Smoke detection alarm device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Smoke detection alarm device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Smoke detection alarm device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-729572