Si bien los transistores unijunción ya no son componentes muy usados, con ellos el diseño de una sirena es bastante simplificado. En este artículo describimos el montaje de una que funciona con tensiones de 12 V.

   Describimos el montaje de una buena sirena para uso automotor o incluso fijo, con fuente apropiada, alimentada por tensión de 12 V.

   El circuito utiliza un transistor unijunción que opera en la configuración básica de oscilador de relajación.

   En este circuito, el capacitor C1 se carga a través de varios resistores que forman una red RC hasta el punto de disparo.

   De esta forma, una señal con la forma de onda mostrada en la figura 1 se produce, sirviendo para controlar un segundo oscilador.

 

   Figura 1 - Señal generada por el unijunción
   Figura 1 - Señal generada por el unijunción

 

   

El segundo oscilador utiliza dos transistores complementarios, siendo el segundo de potencia, con capacidad para excitar directamente un altavoz.

   La frecuencia básica, determinada por C3 es variada por el signo del unijunción con un efecto de modulación que imita una sirena.

 

   Montaje

   En la figura 2 tenemos el circuito completo de la sirena.

 

   Figura 2 - Circuito completo de la sirena
   Figura 2 - Circuito completo de la sirena

 

   Su montaje se puede hacer en una pequeña placa de circuito impreso con la disposición de componentes mostrada en la figura 3.

 

   Figura 3 - Placa de circuito impreso para el montaje
   Figura 3 - Placa de circuito impreso para el montaje

 

   En el montaje, observe la colocación del transistor unijunción y de los demás transistores.

   El transistor de potencia debe estar dotado de un disipador de calor pequeño.

   Los resistores son de 1/8 W con cualquier tolerancia y los capacitores electrolíticos para 16 V o más.

   El altavoz debe tener al menos 15 cm con 4 ó 8 ohmios y un buen rendimiento.

   

Q1 - 2N2646 - transistores unijunción

Q1 - BC548 - transistores NPN de uso general

Q2 - TIP32 - transistores PNP de potencia

S1 - Interruptor de presión NA

FTE - 4 ó 8 ohmios - Altavoz

F1 - Fusible de 2 A

C1 - 47 uF - capacitor electrolítico

C2 - 22 uF - capacitor electrolítico

C3 - 100 uF - capacitor electrolítico

R1 - 470 ohms - resistor - amarillo, violeta, marrón

R2 - 330 ohms - resistor - naranja, naranja, marrón

R3 - 10 k ohms - resistor - marrón, negro, naranja

R4 - 2k2 ohms - resistor - rojo, rojo, rojo

R5 - 47 k ohms - resistor - amarillo, violeta, naranja

R6 - 1 k ohms - resistor - marrón, negro, rojo

Varios:

Placa de circuito impreso, soporte para fusible, disipador para el transistor, hilos, soldadura, etc.

 

18.929MBMemory Usage40.14msRequest Duration
Joomla! Version5.2.3
PHP Version8.3.20
Identityguest
Response200
Templatecassiopeia
Database
Server
mysql
Version
10.5.22-MariaDB
Collation
latin1_swedish_ci
Conn Collation
utf8mb4_general_ci
$_GET
[]
$_POST
[]
$_SESSION
array:1 [ "joomla" => "***redacted***" ]
$_COOKIE
array:1 [ "c2123392c06423339225f3431360b7e6" => "6f6iincoh4oh038dgmltb8igjd" ]
$_SERVER
array:50 [ "USER" => "apache" "HOME" => "/usr/share/httpd" "PATH_TRANSLATED" => "redirect:/ind...
session
array:3 [ "counter" => 4 "timer" => array:3 [ "start" => 1751998500 "last" => 1751998502...
registry
array:3 [ "data" => [] "initialized" => false "separator" => "." ]
user
array:21 [ "id" => 0 "name" => null "username" => null "email" => null "password" => "***r...
  • afterLoad (85.59KB) (233μs)
  • afterInitialise (1.14MB) (3.17ms)
  • afterRoute (179.16KB) (829μs)
  • beforeRenderComponent com_content (100.7KB) (414μs)
  • Before Access::preloadComponents (all components) (33.45KB) (201μs)
  • After Access::preloadComponents (all components) (107.06KB) (363μs)
  • Before Access::preloadPermissions (com_content) (1.57KB) (9μs)
  • After Access::preloadPermissions (com_content) (16.22MB) (19.25ms)
  • Before Access::getAssetRules (id:8299 name:com_content.article.12372) (514.65KB) (650μs)
  • After Access::getAssetRules (id:8299 name:com_content.article.12372) (7.38KB) (48μs)
  • afterRenderComponent com_content (378.8KB) (7.3ms)
  • afterDispatch (2.25KB) (55μs)
  • beforeRenderRawModule mod_articles_category (Banco de Circuitos) (358.44KB) (1.71ms)
  • afterRenderRawModule mod_articles_category (Banco de Circuitos) (79.43KB) (363μs)
  • beforeRenderRawModule mod_finder (Busca_inteligente) (5.9KB) (95μs)
  • afterRenderRawModule mod_finder (Busca_inteligente) (64.9KB) (1.18ms)
  • beforeRenderModule mod_articles_category (Banco de Circuitos) (9.27KB) (577μs)
  • afterRenderModule mod_articles_category (Banco de Circuitos) (5.47KB) (77μs)
  • beforeRenderModule mod_finder (Busca_inteligente) (6.64KB) (193μs)
  • afterRenderModule mod_finder (Busca_inteligente) (4.75KB) (52μs)
  • afterRender (250.06KB) (3.26ms)
  • 1 x After Access::preloadPermissions (com_content) (16.22MB) (47.95%)
    19.25ms
    1 x afterRenderComponent com_content (378.8KB) (18.19%)
    7.30ms
    1 x afterRender (250.06KB) (8.11%)
    3.26ms
    1 x afterInitialise (1.14MB) (7.89%)
    3.17ms
    1 x beforeRenderRawModule mod_articles_category (Banco de Circuitos) (358.44KB) (4.26%)
    1.71ms
    1 x afterRenderRawModule mod_finder (Busca_inteligente) (64.9KB) (2.95%)
    1.18ms
    1 x afterRoute (179.16KB) (2.07%)
    829μs
    1 x Before Access::getAssetRules (id:8299 name:com_content.article.12372) (514.65KB) (1.62%)
    650μs
    1 x beforeRenderModule mod_articles_category (Banco de Circuitos) (9.27KB) (1.44%)
    577μs
    1 x beforeRenderComponent com_content (100.7KB) (1.03%)
    414μs
    1 x afterRenderRawModule mod_articles_category (Banco de Circuitos) (79.43KB) (0.9%)
    363μs
    1 x After Access::preloadComponents (all components) (107.06KB) (0.9%)
    363μs
    1 x afterLoad (85.59KB) (0.58%)
    233μs
    1 x Before Access::preloadComponents (all components) (33.45KB) (0.5%)
    201μs
    1 x beforeRenderModule mod_finder (Busca_inteligente) (6.64KB) (0.48%)
    193μs
    1 x beforeRenderRawModule mod_finder (Busca_inteligente) (5.9KB) (0.24%)
    95μs
    1 x afterRenderModule mod_articles_category (Banco de Circuitos) (5.47KB) (0.19%)
    77μs
    1 x afterDispatch (2.25KB) (0.14%)
    55μs
    1 x afterRenderModule mod_finder (Busca_inteligente) (4.75KB) (0.13%)
    52μs
    1 x After Access::getAssetRules (id:8299 name:com_content.article.12372) (7.38KB) (0.12%)
    48μs
    1 x Before Access::preloadPermissions (com_content) (1.57KB) (0.02%)
    9μs
21 statements were executed, 5 of which were duplicates, 16 unique11.05ms1.58MB
  • SELECT @@SESSION.sql_mode;26μs968B/libraries/src/Session/MetadataManager.php:184Copy
  • SELECT `session_id` FROM `incbmx_session` WHERE `session_id` = :session_id LIMIT 149μs1.31KBParams/libraries/src/Session/MetadataManager.php:187Copy
  • UPDATE `incbmx_session` SET `guest` = :guest , `time` = :time , `userid` = :user_id , `username` = :username , `client_id` = :client_id WHERE `session_id` = :session_id47μs992BParams/libraries/src/Session/MetadataManager.php:316Copy
  • SELECT `id`,`rules` FROM `incbmx_viewlevels`43μs608B/libraries/src/Access/Access.php:955Copy
  • SELECT `b`.`id` FROM `incbmx_usergroups` AS `a` LEFT JOIN `incbmx_usergroups` AS `b` ON `b`.`lft` <= `a`.`lft` AND `b`.`rgt` >= `a`.`rgt` WHERE `a`.`id` = :guest67μs1.64KBParams/libraries/src/Access/Access.php:868Copy
  • SELECT `c`.`id`,`c`.`asset_id`,`c`.`access`,`c`.`alias`,`c`.`checked_out`,`c`.`checked_out_time`,`c`.`created_time`,`c`.`created_user_id`,`c`.`description`,`c`.`extension`,`c`.`hits`,`c`.`language`,`c`.`level`,`c`.`lft`,`c`.`metadata`,`c`.`metadesc`,`c`.`metakey`,`c`.`modified_time`,`c`.`note`,`c`.`params`,`c`.`parent_id`,`c`.`path`,`c`.`published`,`c`.`rgt`,`c`.`title`,`c`.`modified_user_id`,`c`.`version`, CASE WHEN CHAR_LENGTH(`c`.`alias`) != 0 THEN CONCAT_WS(':', `c`.`id`, `c`.`alias`) ELSE `c`.`id` END as `slug` FROM `incbmx_categories` AS `s` INNER JOIN `incbmx_categories` AS `c` ON (`s`.`lft` <= `c`.`lft` AND `c`.`lft` < `s`.`rgt`) OR (`c`.`lft` < `s`.`lft` AND `s`.`rgt` < `c`.`rgt`) WHERE (`c`.`extension` = :extension OR `c`.`extension` = 'system') AND `c`.`published` = 1 AND `s`.`id` = :id ORDER BY `c`.`lft`232μs20.2KBParams/libraries/src/Categories/Categories.php:375Copy
  • SELECT `id`,`name`,`rules`,`parent_id` FROM `incbmx_assets` WHERE `name` IN (:preparedArray1,:preparedArray2,:preparedArray3,:preparedArray4,:preparedArray5,:preparedArray6,:preparedArray7,:preparedArray8,:preparedArray9,:preparedArray10,:preparedArray11,:preparedArray12,:preparedArray13,:preparedArray14,:preparedArray15,:preparedArray16,:preparedArray17,:preparedArray18,:preparedArray19,:preparedArray20,:preparedArray21,:preparedArray22,:preparedArray23,:preparedArray24,:preparedArray25,:preparedArray26,:preparedArray27,:preparedArray28,:preparedArray29,:preparedArray30,:preparedArray31,:preparedArray32,:preparedArray33,:preparedArray34,:preparedArray35,:preparedArray36,:preparedArray37,:preparedArray38,:preparedArray39)212μs7.44KBParams/libraries/src/Access/Access.php:357Copy
  • SELECT `id`,`name`,`rules`,`parent_id` FROM `incbmx_assets` WHERE `name` LIKE :asset OR `name` = :extension OR `parent_id` = 07.78ms1.48MBParams/libraries/src/Access/Access.php:301Copy
  • SHOW FULL COLUMNS FROM `incbmx_content`392μs2.39KB/libraries/vendor/joomla/database/src/Mysqli/MysqliDriver.php:587Copy
  • UPDATE `incbmx_content` SET `hits` = (`hits` + 1) WHERE `id` = '12372'191μs48B/libraries/src/Table/Table.php:1348Copy
  • SELECT `a`.`id`,`a`.`asset_id`,`a`.`title`,`a`.`alias`,`a`.`introtext`,`a`.`fulltext`,`a`.`state`,`a`.`catid`,`a`.`created`,`a`.`created_by`,`a`.`created_by_alias`,`a`.`modified`,`a`.`modified_by`,`a`.`checked_out`,`a`.`checked_out_time`,`a`.`publish_up`,`a`.`publish_down`,`a`.`images`,`a`.`urls`,`a`.`attribs`,`a`.`version`,`a`.`ordering`,`a`.`metakey`,`a`.`metadesc`,`a`.`access`,`a`.`hits`,`a`.`metadata`,`a`.`featured`,`a`.`language`,`fp`.`featured_up`,`fp`.`featured_down`,`c`.`title` AS `category_title`,`c`.`alias` AS `category_alias`,`c`.`access` AS `category_access`,`c`.`language` AS `category_language`,`fp`.`ordering`,`u`.`name` AS `author`,`parent`.`title` AS `parent_title`,`parent`.`id` AS `parent_id`,`parent`.`path` AS `parent_route`,`parent`.`alias` AS `parent_alias`,`parent`.`language` AS `parent_language`,ROUND(`v`.`rating_sum` / `v`.`rating_count`, 1) AS `rating`,`v`.`rating_count` AS `rating_count` FROM `incbmx_content` AS `a` INNER JOIN `incbmx_categories` AS `c` ON `c`.`id` = `a`.`catid` LEFT JOIN `incbmx_content_frontpage` AS `fp` ON `fp`.`content_id` = `a`.`id` LEFT JOIN `incbmx_users` AS `u` ON `u`.`id` = `a`.`created_by` LEFT JOIN `incbmx_categories` AS `parent` ON `parent`.`id` = `c`.`parent_id` LEFT JOIN `incbmx_content_rating` AS `v` ON `a`.`id` = `v`.`content_id` WHERE ( (`a`.`id` = :pk AND `c`.`published` > 0) AND (`a`.`publish_up` IS NULL OR `a`.`publish_up` <= :publishUp)) AND (`a`.`publish_down` IS NULL OR `a`.`publish_down` >= :publishDown) AND `a`.`state` IN (:preparedArray1,:preparedArray2)178μs22.13KBParams/components/com_content/src/Model/ArticleModel.php:215Copy
  • SELECT `c`.`id`,`c`.`asset_id`,`c`.`access`,`c`.`alias`,`c`.`checked_out`,`c`.`checked_out_time`,`c`.`created_time`,`c`.`created_user_id`,`c`.`description`,`c`.`extension`,`c`.`hits`,`c`.`language`,`c`.`level`,`c`.`lft`,`c`.`metadata`,`c`.`metadesc`,`c`.`metakey`,`c`.`modified_time`,`c`.`note`,`c`.`params`,`c`.`parent_id`,`c`.`path`,`c`.`published`,`c`.`rgt`,`c`.`title`,`c`.`modified_user_id`,`c`.`version`, CASE WHEN CHAR_LENGTH(`c`.`alias`) != 0 THEN CONCAT_WS(':', `c`.`id`, `c`.`alias`) ELSE `c`.`id` END as `slug` FROM `incbmx_categories` AS `s` INNER JOIN `incbmx_categories` AS `c` ON (`s`.`lft` <= `c`.`lft` AND `c`.`lft` < `s`.`rgt`) OR (`c`.`lft` < `s`.`lft` AND `s`.`rgt` < `c`.`rgt`) WHERE (`c`.`extension` = :extension OR `c`.`extension` = 'system') AND `c`.`access` IN (:preparedArray1,:preparedArray2) AND `c`.`published` = 1 AND `s`.`id` = :id ORDER BY `c`.`lft`242μs3.92KBParams/libraries/src/Categories/Categories.php:375Copy
  • SELECT `m`.`tag_id`,`t`.* FROM `incbmx_contentitem_tag_map` AS `m` INNER JOIN `incbmx_tags` AS `t` ON `m`.`tag_id` = `t`.`id` WHERE `m`.`type_alias` = :contentType AND `m`.`content_item_id` = :id AND `t`.`published` = 1 AND `t`.`access` IN (:preparedArray1,:preparedArray2)267μs4.02KBParams/libraries/src/Helper/TagsHelper.php:388Copy
  • SELECT `c`.`id`,`c`.`asset_id`,`c`.`access`,`c`.`alias`,`c`.`checked_out`,`c`.`checked_out_time`,`c`.`created_time`,`c`.`created_user_id`,`c`.`description`,`c`.`extension`,`c`.`hits`,`c`.`language`,`c`.`level`,`c`.`lft`,`c`.`metadata`,`c`.`metadesc`,`c`.`metakey`,`c`.`modified_time`,`c`.`note`,`c`.`params`,`c`.`parent_id`,`c`.`path`,`c`.`published`,`c`.`rgt`,`c`.`title`,`c`.`modified_user_id`,`c`.`version`, CASE WHEN CHAR_LENGTH(`c`.`alias`) != 0 THEN CONCAT_WS(':', `c`.`id`, `c`.`alias`) ELSE `c`.`id` END as `slug` FROM `incbmx_categories` AS `s` INNER JOIN `incbmx_categories` AS `c` ON (`s`.`lft` <= `c`.`lft` AND `c`.`lft` < `s`.`rgt`) OR (`c`.`lft` < `s`.`lft` AND `s`.`rgt` < `c`.`rgt`) WHERE (`c`.`extension` = :extension OR `c`.`extension` = 'system') AND `c`.`access` IN (:preparedArray1,:preparedArray2) AND `c`.`published` = 1 AND `s`.`id` = :id ORDER BY `c`.`lft`173μs3.92KBParams/libraries/src/Categories/Categories.php:375Copy
  • SELECT DISTINCT a.id, a.title, a.name, a.checked_out, a.checked_out_time, a.note, a.state, a.access, a.created_time, a.created_user_id, a.ordering, a.language, a.fieldparams, a.params, a.type, a.default_value, a.context, a.group_id, a.label, a.description, a.required, a.only_use_in_subform,l.title AS language_title, l.image AS language_image,uc.name AS editor,ag.title AS access_level,ua.name AS author_name,g.title AS group_title, g.access as group_access, g.state AS group_state, g.note as group_note FROM incbmx_fields AS a LEFT JOIN `incbmx_languages` AS l ON l.lang_code = a.language LEFT JOIN incbmx_users AS uc ON uc.id=a.checked_out LEFT JOIN incbmx_viewlevels AS ag ON ag.id = a.access LEFT JOIN incbmx_users AS ua ON ua.id = a.created_user_id LEFT JOIN incbmx_fields_groups AS g ON g.id = a.group_id LEFT JOIN `incbmx_fields_categories` AS fc ON fc.field_id = a.id WHERE ( (`a`.`context` = :context AND (`fc`.`category_id` IS NULL OR `fc`.`category_id` IN (:preparedArray1,:preparedArray2,:preparedArray3)) AND `a`.`access` IN (:preparedArray4,:preparedArray5)) AND (`a`.`group_id` = 0 OR `g`.`access` IN (:preparedArray6,:preparedArray7)) AND `a`.`state` = :state) AND (`a`.`group_id` = 0 OR `g`.`state` = :gstate) AND `a`.`only_use_in_subform` = :only_use_in_subform ORDER BY a.ordering ASC476μs4.81KBParams/libraries/src/MVC/Model/BaseDatabaseModel.php:164Copy
  • SELECT `c`.`id`,`c`.`asset_id`,`c`.`access`,`c`.`alias`,`c`.`checked_out`,`c`.`checked_out_time`,`c`.`created_time`,`c`.`created_user_id`,`c`.`description`,`c`.`extension`,`c`.`hits`,`c`.`language`,`c`.`level`,`c`.`lft`,`c`.`metadata`,`c`.`metadesc`,`c`.`metakey`,`c`.`modified_time`,`c`.`note`,`c`.`params`,`c`.`parent_id`,`c`.`path`,`c`.`published`,`c`.`rgt`,`c`.`title`,`c`.`modified_user_id`,`c`.`version`, CASE WHEN CHAR_LENGTH(`c`.`alias`) != 0 THEN CONCAT_WS(':', `c`.`id`, `c`.`alias`) ELSE `c`.`id` END as `slug` FROM `incbmx_categories` AS `s` INNER JOIN `incbmx_categories` AS `c` ON (`s`.`lft` <= `c`.`lft` AND `c`.`lft` < `s`.`rgt`) OR (`c`.`lft` < `s`.`lft` AND `s`.`rgt` < `c`.`rgt`) WHERE (`c`.`extension` = :extension OR `c`.`extension` = 'system') AND `c`.`access` IN (:preparedArray1,:preparedArray2) AND `c`.`published` = 1 AND `s`.`id` = :id ORDER BY `c`.`lft`176μs3.92KBParams/libraries/src/Categories/Categories.php:375Copy
  • SELECT `name`,`element` FROM `incbmx_extensions` WHERE `type` = 'plugin' AND `folder` = 'finder' AND `enabled` = 1143μs1.89KB/administrator/components/com_finder/src/Helper/LanguageHelper.php:135Copy
  • SELECT `title` FROM `incbmx_finder_taxonomy` WHERE `parent_id` = 1 AND `state` = 1 AND `access` IN (1,5)81μs648B/administrator/components/com_finder/src/Indexer/Taxonomy.php:325Copy
  • SELECT * FROM `incbmx_schemaorg` WHERE `itemId` = :itemId AND `context` = :context58μs1.55KBParams/plugins/system/schemaorg/src/Extension/Schemaorg.php:403Copy
  • SELECT `a`.`id`,`a`.`asset_id`,`a`.`title`,`a`.`alias`,`a`.`introtext`,`a`.`fulltext`,`a`.`state`,`a`.`catid`,`a`.`created`,`a`.`created_by`,`a`.`created_by_alias`,`a`.`modified`,`a`.`modified_by`,`a`.`checked_out`,`a`.`checked_out_time`,`a`.`publish_up`,`a`.`publish_down`,`a`.`images`,`a`.`urls`,`a`.`attribs`,`a`.`version`,`a`.`ordering`,`a`.`metakey`,`a`.`metadesc`,`a`.`access`,`a`.`hits`,`a`.`metadata`,`a`.`featured`,`a`.`language`,`fp`.`featured_up`,`fp`.`featured_down`,`c`.`title` AS `category_title`,`c`.`alias` AS `category_alias`,`c`.`access` AS `category_access`,`c`.`language` AS `category_language`,`fp`.`ordering`,`u`.`name` AS `author`,`parent`.`title` AS `parent_title`,`parent`.`id` AS `parent_id`,`parent`.`path` AS `parent_route`,`parent`.`alias` AS `parent_alias`,`parent`.`language` AS `parent_language`,ROUND(`v`.`rating_sum` / `v`.`rating_count`, 1) AS `rating`,`v`.`rating_count` AS `rating_count` FROM `incbmx_content` AS `a` INNER JOIN `incbmx_categories` AS `c` ON `c`.`id` = `a`.`catid` LEFT JOIN `incbmx_content_frontpage` AS `fp` ON `fp`.`content_id` = `a`.`id` LEFT JOIN `incbmx_users` AS `u` ON `u`.`id` = `a`.`created_by` LEFT JOIN `incbmx_categories` AS `parent` ON `parent`.`id` = `c`.`parent_id` LEFT JOIN `incbmx_content_rating` AS `v` ON `a`.`id` = `v`.`content_id` WHERE ( (`a`.`id` = :pk AND `c`.`published` > 0) AND (`a`.`publish_up` IS NULL OR `a`.`publish_up` <= :publishUp)) AND (`a`.`publish_down` IS NULL OR `a`.`publish_down` >= :publishDown) AND `a`.`state` IN (:preparedArray1,:preparedArray2)152μs22.17KBParams/components/com_content/src/Model/ArticleModel.php:215Copy
  • SELECT SUM(CASE WHEN `a`.`next_execution` <= :now THEN 1 ELSE 0 END) AS due_count,SUM(CASE WHEN `a`.`locked` IS NULL THEN 0 ELSE 1 END) AS locked_count FROM `incbmx_scheduler_tasks` AS `a` WHERE `a`.`state` = 169μs1.37KBParams/administrator/components/com_scheduler/src/Model/TasksModel.php:465Copy