FR2377069A1 - Smoke detector system with electrical operation of ionisation chamber - has step level circuit which includes programmable unijunction transistor - Google Patents
Smoke detector system with electrical operation of ionisation chamber - has step level circuit which includes programmable unijunction transistorInfo
- Publication number
- FR2377069A1 FR2377069A1 FR7700547A FR7700547A FR2377069A1 FR 2377069 A1 FR2377069 A1 FR 2377069A1 FR 7700547 A FR7700547 A FR 7700547A FR 7700547 A FR7700547 A FR 7700547A FR 2377069 A1 FR2377069 A1 FR 2377069A1
- Authority
- FR
- France
- Prior art keywords
- step level
- ionisation chamber
- level circuit
- smoke detector
- transistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
- G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas
Abstract
The smoke detector has an ionisation chamber which includes a radiation source and two separated electrodes. The ionisation chamber has an electrical resistance which varies as a function of the smoke in the free space between the electrodes. A resistive element is connected in series with one of the chambers electrodes so as to form a first voltage divider. The junction of the resistive element and the electrode forms the dividers output. An annunciator is actuated by a signal from a step level circuit to provide an alarm. The step level circuit is connected between the output of the first divider and the annunciator so as to detect a dangerous concentration of smoke in the chambers. The step circuit includes a programmable unifunction transistor (50) and a second voltage divider which establishes the step level. The control electrode of the unifunction transistor (50) is connected to the output of one of the dividers. The anode (17) of the transistor (50) is connected to the other divider (52a).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7700547A FR2377069A1 (en) | 1977-01-11 | 1977-01-11 | Smoke detector system with electrical operation of ionisation chamber - has step level circuit which includes programmable unijunction transistor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7700547A FR2377069A1 (en) | 1977-01-11 | 1977-01-11 | Smoke detector system with electrical operation of ionisation chamber - has step level circuit which includes programmable unijunction transistor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| FR2377069A1 true FR2377069A1 (en) | 1978-08-04 |
Family
ID=9185311
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| FR7700547A Withdrawn FR2377069A1 (en) | 1977-01-11 | 1977-01-11 | Smoke detector system with electrical operation of ionisation chamber - has step level circuit which includes programmable unijunction transistor |
Country Status (1)
| Country | Link |
|---|---|
| FR (1) | FR2377069A1 (en) |
-
1977
- 1977-01-11 FR FR7700547A patent/FR2377069A1/en not_active Withdrawn
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| ST | Notification of lapse |