{"id":94039,"date":"2022-04-07T12:20:55","date_gmt":"2022-04-07T06:50:55","guid":{"rendered":"https:\/\/www.electronicsforu.com\/?p=94039"},"modified":"2024-07-29T17:06:51","modified_gmt":"2024-07-29T11:36:51","slug":"variable-power-supply-for-up-to-3a-current","status":"publish","type":"post","link":"https:\/\/www.electronicsforu.com\/electronics-projects\/variable-power-supply-for-up-to-3a-current","title":{"rendered":"Variable Power Supply For Up To 3A Current"},"content":{"rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"alignright size-thumbnail wp-image-36742\" src=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2017\/06\/saninew-150x150.jpg\" alt=\"\" width=\"150\" height=\"150\" srcset=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2017\/06\/saninew-150x150.jpg 150w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2017\/06\/saninew.jpg 308w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/>The circuit presented here can provide up to three amperes of current for a 5V, 6V, 8V, or 9V supply. It uses the popular adjustable voltage regulator <a href=\"https:\/\/www.ti.com\/product\/LM317\" target=\"_blank\" rel=\"noopener\">LM317<\/a>, which is inexpensive and is used generally for variable power supplies with up to 1.5 ampere current.<\/p>\n<p>With the addition of PNP transistor TIP127 in the circuit, we get a 5V to 9V variable power supply with 3A current rating. However, suitable heatsinks for LM317, TIP127, LM7809 and an exhaust fan for cooling the TIP127 are required.<\/p>\n<p><center><iframe loading=\"lazy\" title=\"YouTube video player\" src=\"https:\/\/www.youtube.com\/embed\/ERwVWsJxQlo\" width=\"560\" height=\"315\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/center><\/p>\n<figure id=\"attachment_94041\" aria-describedby=\"caption-attachment-94041\" style=\"width: 500px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-94041 size-medium\" src=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/1-4-500x356.jpg\" alt=\"Author\u2019s prototype\" width=\"500\" height=\"356\" srcset=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/1-4-500x356.jpg 500w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/1-4-1024x729.jpg 1024w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/1-4-696x495.jpg 696w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/1-4-590x420.jpg 590w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/1-4-100x70.jpg 100w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/1-4.jpg 1048w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><figcaption id=\"caption-attachment-94041\" class=\"wp-caption-text\">Fig. 1: Author\u2019s prototype<\/figcaption><\/figure>\n<p>The author\u2019s prototype is shown in Fig. 1. The block diagram of the variable power supply is shown in Fig. 2 and its circuit diagram in Fig. 3.<\/p>\n<figure id=\"attachment_94042\" aria-describedby=\"caption-attachment-94042\" style=\"width: 500px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-94042 size-medium\" src=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/2-4-500x207.jpg\" alt=\"Block diagram\" width=\"500\" height=\"207\" srcset=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/2-4-500x207.jpg 500w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/2-4-696x289.jpg 696w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/2-4.jpg 938w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><figcaption id=\"caption-attachment-94042\" class=\"wp-caption-text\">Fig. 2: Block diagram<\/figcaption><\/figure>\n<figure id=\"attachment_94043\" aria-describedby=\"caption-attachment-94043\" style=\"width: 500px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-94043 size-medium\" src=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/3-3-500x188.jpg\" alt=\"Circuit diagram\" width=\"500\" height=\"188\" srcset=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/3-3-500x188.jpg 500w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/3-3-1024x385.jpg 1024w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/3-3-1536x578.jpg 1536w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/3-3-696x262.jpg 696w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/3-3-1068x402.jpg 1068w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/3-3-1117x420.jpg 1117w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/3-3.jpg 2026w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><figcaption id=\"caption-attachment-94043\" class=\"wp-caption-text\">Fig. 3: Circuit diagram<\/figcaption><\/figure>\n<h2>Circuit and working<\/h2>\n<p>The variable power supply is built around step-down transformer X1, four 1N5408 rectifier diodes D1 through D4, an LED, TIP127 transistor T1, LM317 adjustable voltage regulator IC1, 9V voltage regulator IC2, and a DC digital panel meter (DPM). A 22-ohm, 2-watt resistor (R1) is connected between the base and emitter of T1 to control the current. Pot VR1 is used to control the output voltage. The output voltage can be seen on the DPM.<\/p>\n<p>The output voltage can be set to 9V and the current drawn is around 3A. The voltage across resistor R1 makes transistor T1 to conduct and most of the current is drawn from emitter to collector of T1. As lesser current passes through LM317 and most of the current flows through T1, heatsink of IC1 is less warm as compared to the heat sink of transistor T1 heat sink. So the heat sink for T1 needs to be bigger than the heat sink for IC2 and IC3. Use of exhaust fan helps in proper dissipation of the heat. With more current needed by the load, transistor T1 conducts more and the current bypasses the LM317.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-medium wp-image-94047\" src=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/7-258x500.jpg\" alt=\"\" width=\"258\" height=\"500\" srcset=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/7-258x500.jpg 258w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/7-528x1024.jpg 528w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/7-216x420.jpg 216w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/04\/7.jpg 636w\" sizes=\"auto, (max-width: 258px) 100vw, 258px\" \/><\/p>\n<p>LED1 glows when 230V AC supply is on. VR1 is used to vary the output voltages according to your requirement. The voltage is shown on DPM.<\/p>\n<div class=\"mepr_error\"><div class=\"locked-content\">\n<b>EFY++ CONTENT: ACCESS TO THIS CONTENT IS FREE! BUT YOU NEED TO BE A REGISTERED USER.<\/b><\/p>\n<p>Oops! This is an EFY++ article, which means it's our Premium Content. You need to be a Registered User of our website to read its complete content.<\/p>\n<p><b>Good News: <\/b>You can register to our website for FREE! <a href=\"https:\/\/www.electronicsforu.com\/plans\/subscription-plans\" target=\"_blank\" rel=\"noopener\">CLICK HERE<\/a> to register now.<\/p>\n<p><b>Already a registered member? <\/b>If YES, then simply login to you account below. (TIP: Use 'forgot password' feature and reset and save your new password in your browser, if you forgot the last one!)\n<\/div>\n<\/div><div>\n<div class=\"mp_wrapper mp_login_form\">\n                  <!-- mp-login-form-start -->     <form name=\"mepr_loginform\" id=\"mepr_loginform\" class=\"mepr-form\" action=\"https:\/\/www.electronicsforu.com\/login\" method=\"post\">\n            <div class=\"mp-form-row mepr_username\">\n        <div class=\"mp-form-label\">\n                              <label for=\"user_login\">Username<\/label>\n        <\/div>\n        <input type=\"text\" name=\"log\" id=\"user_login\" value=\"\" \/>\n      <\/div>\n      <div class=\"mp-form-row mepr_password\">\n        <div class=\"mp-form-label\">\n          <label for=\"user_pass\">Password<\/label>\n          <div class=\"mp-hide-pw\">\n            <input type=\"password\" name=\"pwd\" id=\"user_pass\" value=\"\" \/>\n            <button type=\"button\" class=\"button mp-hide-pw hide-if-no-js\" data-toggle=\"0\" aria-label=\"Show password\">\n              <span class=\"dashicons dashicons-visibility\" aria-hidden=\"true\"><\/span>\n            <\/button>\n          <\/div>\n        <\/div>\n      <\/div>\n            <div>\n        <label><input name=\"rememberme\" type=\"checkbox\" id=\"rememberme\" value=\"forever\" \/> Remember Me<\/label>\n      <\/div>\n      <div class=\"mp-spacer\">&nbsp;<\/div>\n      <div class=\"submit\">\n        <input type=\"submit\" name=\"wp-submit\" id=\"wp-submit\" class=\"button-primary mepr-share-button \" value=\"Log In\" \/>\n        <input type=\"hidden\" name=\"redirect_to\" value=\"\/wp-json\/wp\/v2\/posts\/94039\" \/>\n        <input type=\"hidden\" name=\"mepr_process_login_form\" value=\"true\" \/>\n        <input type=\"hidden\" name=\"mepr_is_login_page\" value=\"false\" \/>\n      <\/div>\n    <\/form>\n    <div class=\"mp-spacer\">&nbsp;<\/div>\n    <div class=\"mepr-login-actions\">\n      <a href=\"https:\/\/www.electronicsforu.com\/login?action=forgot_password\">Forgot Password<\/a>\n    <\/div>\n\n      \n    <!-- mp-login-form-end --> \n  <\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>The circuit presented here can provide up to three amperes of current for a 5V, 6V, 8V, or 9V supply. It uses the popular adjustable voltage regulator LM317, which is inexpensive and is used generally for variable power supplies with up to 1.5 ampere current. With the addition of PNP transistor TIP127 in the circuit, [&hellip;]<\/p>\n","protected":false},"author":106036,"featured_media":94041,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22,23,3713],"tags":[10364,1985,1911,110,83,8296],"class_list":{"0":"post-94039","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-electronics-projects","8":"category-hardware-diy","9":"category-premium","10":"tag-apr-2022","11":"tag-diy-projects","12":"tag-do-it-yourself","13":"tag-electronics-projects","14":"tag-featured","15":"tag-premium"},"_links":{"self":[{"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/posts\/94039","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/users\/106036"}],"replies":[{"embeddable":true,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/comments?post=94039"}],"version-history":[{"count":1,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/posts\/94039\/revisions"}],"predecessor-version":[{"id":144792,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/posts\/94039\/revisions\/144792"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/media\/94041"}],"wp:attachment":[{"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/media?parent=94039"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/categories?post=94039"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/tags?post=94039"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}