{"id":1953,"date":"2018-08-15T17:00:55","date_gmt":"2018-08-15T17:00:55","guid":{"rendered":"https:\/\/ibex.tech\/resources\/?p=1953"},"modified":"2022-02-18T15:05:16","modified_gmt":"2022-02-18T15:05:16","slug":"designing-for-phototransistors","status":"publish","type":"post","link":"https:\/\/ibex.tech\/resources\/geek-area\/electronics\/phototransistors\/designing-for-phototransistors","title":{"rendered":"Designing for phototransistors"},"content":{"rendered":"<h4>\nPhototransistor basics<br \/>\n<\/h4>\n<p>\nWide band vs narrow band photo diode\n<\/p>\n<p style=\"margin-left: 40px;\">\nWide band components can see a wider range of colours \/ wavelengths, narrow band is more centered on a specific colour&nbsp;\/ wavelength\n<\/p>\n<h4>\nBasic typical detect circuits<br \/>\n<\/h4>\n<p>\nCommon-Emitter Amplifier (often used):\n<\/p>\n<p>\n<a href=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/phototransistor1.png\"><img loading=\"lazy\" decoding=\"async\" alt=\"\" class=\"alignnone size-full wp-image-1955\" height=\"193\" src=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/phototransistor1.png\" width=\"100\" srcset=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/phototransistor1.png 100w, https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/phototransistor1-31x60.png 31w, https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/phototransistor1-78x150.png 78w\" sizes=\"auto, (max-width: 100px) 100vw, 100px\" \/><\/a>\n<\/p>\n<p>\nCommon-Collector Amplifier:\n<\/p>\n<p>\n<a href=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/phototransistor2.png\"><img loading=\"lazy\" decoding=\"async\" alt=\"\" class=\"alignnone size-full wp-image-1956\" height=\"196\" src=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/phototransistor2.png\" width=\"98\" srcset=\"https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/phototransistor2.png 98w, https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/phototransistor2-30x60.png 30w, https:\/\/ibex.tech\/resources\/wp-content\/uploads\/sites\/3\/phototransistor2-75x150.png 75w\" sizes=\"auto, (max-width: 98px) 100vw, 98px\" \/><\/a>\n<\/p>\n<p>\nThe current generated in the component when light is detected is very small, but the phototransistor is basically and&nbsp;an internal amplifier which magnifies this current to useful levels.\n<\/p>\n<p>\nThe phototransistor generates a response proportional to the light received by the component up to a certain light level. When the amount of light surpasses that level, the phototransistor becomes saturated and<br \/>\nthe output will not increase even as the light level increases.&nbsp;&nbsp;By adjusting the load resistor in the amplifier circuit one can set the mode of operation between measuring light level or using the phototransistor as a switch.&nbsp; Bear in mind that changing the load resistor will likely alter the response time of the device (lower resistance = higher current = faster response often).\n<\/p>\n<h4>\nUsing a phototransistor to measure light level<br \/>\n<\/h4>\n<p>\nVCC &gt; RL&nbsp;x Ic\n<\/p>\n<p>\n&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Phototransistor basics Wide band vs narrow band photo diode Wide band components can see a wider range of colours \/ wavelengths, narrow band is more centered on a specific colour&nbsp;\/ wavelength Basic typical detect circuits Common-Emitter Amplifier (often used): Common-Collector Amplifier: The current generated in the component when light is detected is very small, but [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[110],"tags":[],"class_list":["post-1953","post","type-post","status-publish","format-standard","hentry","category-phototransistors"],"_links":{"self":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1953","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/comments?post=1953"}],"version-history":[{"count":4,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1953\/revisions"}],"predecessor-version":[{"id":1959,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/posts\/1953\/revisions\/1959"}],"wp:attachment":[{"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/media?parent=1953"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/categories?post=1953"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ibex.tech\/resources\/wp-json\/wp\/v2\/tags?post=1953"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}