An experimental crystal oscillator FM transmitter

Many radio enthusiasts want to make an FM transmitter, especially in the 87-108MHz FM band, which can be received by off-the-shelf FM radios, which is popular among everyone.
Examples of FM transmitters have been introduced in many publications, but most of them use capacitive three-point circuits and Krato oscillator circuits. Although this circuit is simple, its frequency stability is not high, especially in amateur conditions, the frequency changes when the circuit board or antenna position is slightly moved. Here I introduce a FM transmitter that uses a crystal to stabilize the frequency.
Circuit principle

As shown in Figure 1, a level 1 audio amplifier circuit is formed by V1 and related resistance-capacitance components, which provide a sufficient intensity audio signal for the modulation level. D1 is a varactor diode, and its equivalent capacitance changes with the reverse voltage applied by the two poles, so that the center frequency of the oscillator composed of the crystal oscillator and the peripheral circuit changes accordingly, and the purpose of frequency modulation is achieved. The signal output by the oscillator is frequency-multiplied and amplified by V3, and then output by the tuning transformer after matching and filtering.
This circuit uses a tuned transformer, so the core must be adjusted after production to make it match. The method is to make a simple field strength circuit (as shown in Figure 2), connect it to the output of the transformer, and adjust the magnetic core until the ammeter indicates the maximum value. Use components with good high-frequency characteristics as much as possible for the components used in the circuit. The crystal chooses a crystal with a nominal value between 29 and 36MHz. D1 can use MV2105. The transformer needs to be self-made. The middle of the TV can be used as the skeleton. The shielding cover is removed, and the enameled wire around ∮0.2mm is wound around the skeleton for 3 turns. Level turns 1 turn. The antenna can be replaced by a 1/4 wavelength flexible wire.

In-depth analysis of the first-level cache and second-level cache of the technical zone CPU eMMC mass burning dilemma, do you really know? Isolation flyback and non-isolated BUCK application design plan Schottky barrier diode selection and application guide How to use Altium in program design Designer puzzle?

Follow WeChat

Interesting and informative information and technical dry goods

Download Audiophile APP

Create your own personal electronic circle

Follow the audiophile class

Lock the latest course activities and technical live broadcast
Collect People collection
share it:
comment
Publish

related suggestion

[Photo] An experimental crystal oscillator FM transmitter

Published on 2006-04-15 20:59 • 670 views
[Photo] An experimental crystal oscillator FM transmitter
[Photo] Self-made 5 Watt FM Transmitter

Published on 2006-04-15 20:49 • 1198 times read
[Photo] Self-made 5 Watt FM Transmitter
[Photo] BA1404 small stereo FM transmitter

Published on 2006-04-15 20:44 • 640 views
[Photo] BA1404 small stereo FM transmitter
[Photo] Small FM transmitter

One. Foreword: Here I will introduce a simple FM transmitter that is easy to manufacture. ...

Published on 2006-04-15 20:44 • 433 views
[Photo] Small FM transmitter
[Photo] Using MEC002A to make a remote FM transmitter

Author: Lin Changhao This article describes several mining ...

Posted at 2006-04-15 20:41 • 467 views
[Photo] Using MEC002A to make a remote FM transmitter
var check_allow = "/d/Api/iscantalk.html"; var add_url = '/ d / article / write /'; function CheckLogin () {now_uid = ''; var ElecfansApi_checklogin = '/ webapi / passport / checklogin'; var logout_url = "{: U ('Login / logout')}"; var logout_url = 'http://bbs.elecfans.com/member.php?mod=logging&action=logout&refer=front'; $ .get (ElecfansApi_checklogin, function (data, textStatus) {if (data! = "") {EchoLoginInfo (data); CheckEmailInfo (data); data = $ .parseJSON (data); now_uid = data.uid; / * var login_content = 'write an article
'+ data.username +'
Quit '; * / var login_content =' write an article
'+ data.username +'
Set exit '; $ (' # login_area '). Html (login_content); var win_width = $ (window) .width (); if (win_width> 1000) {$ ("# mine"). MouseDelay (200) .hover (function () {$ ("# mymenu"). show ();}, function () {$ ("# mymenu"). hide ();});}} else {var content = 'Login Registration'; $ ('# login_area'). html (content); $ (". special-login"). click (function (e) {$ .tActivityLogin (); return false;});}});} $ (function () {// comment ------------------------------- var comment = $ ("# comment"); var comment_input = $ ("# comContent"); // Submit comment click event interaction $ ("# comSubmit2"). on ('click', function () {var content = comment_input.text (); // Empty input box comment_input. html (""). focus (); // Submit data to server $ .ajax ({url: '/plus/arcComment.php', data: {aid: $ ("# webID"). val (), dopost : 'apiPubComment', content: content}, type: 'post', dataType: 'json', success: function (data) {// Data format returned: if (data.status == "successed") {// Build temporary comment DOM var dom = ''; dom + = '
'; dom + =' '; dom + ='
'; dom + ='

'+ data.data.username +' '; dom + ='

'; dom + =' '+ content +' '; dom + =' '; dom + =' just now '; dom + =' '; dom + =' '; // insert a temporary comment to the list $ ("# comment ") .append (dom);} if (data.status ==" failed ") {// alert (data.msg); layer.msg (data.msg);}}}); return false;}); (function () {/ * * Insert single sign-on JS * / var setHost = 'https://passport.elecfans.com'; // Set domain name var script = document.createElement ('script'); script.type = 'text / javascript'; script.src = setHost + '/public/pc/js/t.passport.js'; script.setAttribute ("id", "sso_script"); script.setAttribute ("data-ssoSite", setHost); script.setAttribute ("data-ssoReferer", encodeURIComponent (location.href)); script.setAttribute ("data-ssoSiteid", "11"); var body = document.getElementsByTagName ("body"). item ( 0); body.appendChild (script);}) () / * * It is recommended to modify the style of the article without a picture * * / $ (". Article .thumb"). Each (function () {if ($ (this). find ('img'). attr ('src') == "") {$ (this) .find ('img'). remove (); $ (this) .parent (). css ('padding-left ',' 0px ');}}); / * Baidu share * / window._bd_share_config = {common: {bdText: '', // Custom share content bdDesc: '', // Custom share summary bdUrl: window.location.href, // Custom share URL address bdPic: ''} , share: [{"bdSize": 60, "bdCustomStyle": true}]} with (document) 0 [(getElementsByTagName ('head') [0] || body) .appendChild (createElement ('script')). src = 'http://bdimg.share.baidu.com/static/api/js/share.js?cdnversion=' + ~ (-new Date () / 36e5)]; var add_url = '/ d / article / write / '; // var check_allow = "{: U (' Api / iscantalk ')}"; var check_allow = "/ d / api / iscantalk"; var click_items_length = $ ('. art_click_count '). length; if ( click_items_length> 0) {var id_str = ''; $ ('. art_click_count'). each (function () {id_str + = $ (this) .attr ('data-id') + ',';}) // var url = "{: U ('Api / getclickbyids')}"; var url = "/ d / api / getclickbyids"; var id_data = 'id_str =' + id_str; $ .ajax ({url: url, data: id_data, type: 'post', dataType: 'json', success: function (re) {if (re.list.length> = 1) {var list = re.list; for (var i in list) {var t emp_id = list [i] ['id']; var temp_span = $ (". art_click_count [data-id =" + temp_id + "]") temp_span.html (list [i] ['click']);}} }})} $ ("# comContent"). click (function () {if (now_uid == '') {$ .tActivityLogin (); return false;}}) $ (function () {var follow_wrap = $ ( ".author-collect"); var now_uid = "{$ _super ['uid']}"; var face_src = "{$ _super ['uface']}"; var getFollowNum = $ (". followNum strong"). html (); // Follow $ (window) .on ('click', '.author-collect', function () {if (now_uid == '') {$ .tActivityLogin (); return false;} if ( $ (this) .attr ('id') == 'follow') {$ .post ('/ d / user / follow', {tuid: article_user_id}, function (data) {// Data format returned: if (data.status == "successed") {$ (". followNum strong"). html (++ getFollowNum); follow_wrap.html ('followed'). attr ('id', 'cancelFollow'). css ( 'background', '# 999'); var follow_user = ' '; $ (' # follow_list '). append (follow_user);} if (data.status == "failed") {alert (data.msg);}});} else {// Unfollow if ($ ( this) .attr ('id') == 'cancelFollow') {$ .post ('/ d / user / cancelFollow', {tuid: article_user_id}, function (data) {// Data format returned: if (data .status == "successed") {follow_wrap.html ('Follow'). attr ('id', 'follow'). css ('background', '# f90'); $ (". followNum strong"). html (-getFollowNum); $ ('# follow_list .face'). each (function () {var target_uid = $ (this) .attr ('data-uid'); if (target_uid == now_uid) {$ ( this) .remove ();}})} if (data.status == "failed") {alert (data.msg);}}); return false;}}});});}); / * var myface = "{$ _super ['uid'] | avatar}"; var myname = "{$ _super ['username']}"; var article_id = {$ article ['id']}; var article_user_id = {$ article ['mid']}; // Article author ID $ (function () {<notempty name = "clearnum"> // Reduce the number of reminders var count = parseInt ($ ("# noticeCount"). html ()); count = count-{$ clearnum}; $ ("# noticeCount"). html (count); if ( count

Mechanical Burglary Safes are safes that have passed Chinese 3C certificate and use classical Mechanical Lock to open the safes, with high safety and perfect performance.

Details:

Equipped with classical mechanical locks;

These safes are anti-drilling, anti-burglar and anti-force;

Dual-system protection is contained in safes;

Accurate scale and easy to turn the turntable;

It can`t be opened unless the password has been known;

Not easy to be stolen for the opening process is quite complex.

Mechanical Burglary Safe

Mechanical Burglary Safe,Lock Burglary Strong Safe,Mechanical Fireproof Gun Cabinet ,Mechanical Lock

YONGFA INTELLIGENT TECHNOLOGY SECURITY CO., LTD. , http://www.yongfa-safe.com