karthikeid Posted August 30, 2009 Report Posted August 30, 2009 hii need a fm transmitter circuit that works properly, very urgent pls help me. ::) Quote
Hero999 Posted August 30, 2009 Report Posted August 30, 2009 http://www.silicontronics.com/index.php?action=ezportal;sa=page;p=15 Quote
karthikeid Posted August 31, 2009 Author Report Posted August 31, 2009 can u tell me wheather this circuit works out wellhttp://www.aaroncake.net/circuits/fmtrans.asp Quote
Hero999 Posted August 31, 2009 Report Posted August 31, 2009 I should can this response.That circuit has, no RF buffer amplifier, so the frequency will drift if objects are placed near the antenna, no voltage regulator, so the frequency will change as the battery runs down and no pre-emphasis so it will sound like an AM radio. Quote
karthikeid Posted September 1, 2009 Author Report Posted September 1, 2009 hii have made this circuit http://w1.859.telia.com/~u85920178/tx/bug5.htmat one frequency it is working fine for a long distance but when i speak there is bzz noise nd not able to hear clearly, can u help me to overcome this problem ??? in this circuit i have used 10pf instead of 12pf.... Quote
Hero999 Posted September 1, 2009 Report Posted September 1, 2009 Why did you ask for a circuit that works, if you were only going to build a different one that doesn't work?I could be many things.Are you powering it from a mains adaptor? The internal capacitor might not be large enough so add a 1000 Quote
karthikeid Posted September 2, 2009 Author Report Posted September 2, 2009 hii have powered it by a 9V battery only... Quote
audioguru Posted September 2, 2009 Report Posted September 2, 2009 The electret mic must be connected with the correct polarity. Its metal case has the wire that should be connected to the circuit's ground.The mic must be connected with very short wires or with a shielded audio cable.You must not touch any part of the circuit when it is transmitting to avoid hum pickup from your hands. Quote
karthikeid Posted September 7, 2009 Author Report Posted September 7, 2009 hiin this circuit http://w1.859.telia.com/~u85920178/tx/bug5.htmjust change 547 which is parallel to 2.7pf, into BF494 then it is working fine Quote
karthikeid Posted September 7, 2009 Author Report Posted September 7, 2009 hihttp://rapidshare.com/files/276652026/fm_transmitter.pdf.htmlcheck this circuit need some help building this one... ;D Quote
audioguru Posted September 7, 2009 Report Posted September 7, 2009 hihttp://rapidshare.com/files/276652026/fm_transmitter.pdf.htmlcheck this circuit need some help building this one... ;DPlease attach your schematic here instead of over at RapidShare.The very old circuit will sound bad and have its frequency change when its supply voltage changes.I don't know where you will find a clip-on heatsink for the output transistor. Quote
karthikeid Posted September 7, 2009 Author Report Posted September 7, 2009 hican u provide me some other circuit that will have a good range... Quote
Hero999 Posted September 7, 2009 Report Posted September 7, 2009 I've already done that, read my first reply to this thread. Quote
karthikeid Posted September 7, 2009 Author Report Posted September 7, 2009 hiwhat will be the range atleast 500m... ??? Quote
Hero999 Posted September 7, 2009 Report Posted September 7, 2009 500m through what? Free space, a forest or town?What receiver are you using? A cheap Chinese FM radio won't be able to pick it up from as far away as well as a state of the art car radio.What aerial are you useing? A high gain yagi array will transmit/receive the signal from a long away but will be more directional, a simple monopole will not transmit/recieve the very var but will pickup/send the signal in all directions. Quote
audioguru Posted September 7, 2009 Report Posted September 7, 2009 My FM transmtter has a range of more than 2km to my extremely sensitive home stereo and car radio.Its range is 300m to my cheap Sony Walkman radio.Its range is 100m to a cheap clock radio.Its range is across the street to a cheap scanning radio from The Dollar Store. Quote
karthikeid Posted September 8, 2009 Author Report Posted September 8, 2009 hisome of the components are not presently available to me to build that circuit...but i have attached one more file can u provide me some suggestions on it... i am not able to attach the file here saying the dir is not writable here...so i have uploaded in rapidshare sorry for the inconvince. http://rapidshare.com/files/277282868/transmisso__fm.gif.htmlin this circuit 0.3uH is given how to wind the coil ??? Quote
Hero999 Posted September 8, 2009 Report Posted September 8, 2009 Which components can't you get hold of?It's possible to substitute some of the components.Rapidshare has limited downloads per day unless you pay, for images use www.tinypic.com which has limitless sownloads. Quote
karthikeid Posted September 9, 2009 Author Report Posted September 9, 2009 hithe circuit diagram pls check the working of this circuit... Quote
Hero999 Posted September 9, 2009 Report Posted September 9, 2009 I told you about the problems with that circuit before.You haven't even answered my question.I give up, you're on your own, as you don't seem to want to help yourself, I don't see why I should help you. Quote
karthikeid Posted September 9, 2009 Author Report Posted September 9, 2009 hiok chill hero999...why i am asking is that i have those components with me so that is why i was asking about that circuit....kindly help me out to do this circuit....i cant get LM2931A...is there any substitute ??? Quote
Hero999 Posted September 9, 2009 Report Posted September 9, 2009 You can use the LM78L05 if you like but the battery won't last as long. Quote
audioguru Posted September 9, 2009 Report Posted September 9, 2009 The simple FM transmitter circuit has its tuned circuit connected to its antenna which causes its frequency to change if something moves near the antenna.It does not have a voltage regulator so its frequency also changes as the battery voltage runs down.It does not have pre-emphasis like all FM radio stations have so it will sound muffled like your stereo with its treble tone control turned all the way down.The LM2931 is a 5V low-dropout regulator. All semiconductor manufacturers make some.The 78L05 fails when the battery voltage is less than 7V. A 5V low dropout regulator still works perfectly when the battery voltage has dropped to 5.5V. Quote
mvs sarma Posted September 9, 2009 Report Posted September 9, 2009 hiok chill hero999...why i am asking is that i have those components with me so that is why i was asking about that circuit....kindly help me out to do this circuit....i cant get LM2931A...is there any substitute ???you get LM1117-5 Quote
Hero999 Posted September 9, 2009 Report Posted September 9, 2009 The LM2936-5.0 will work down to 5.2V.The LM7805 will work down to about 6.5V with a low current load. Quote
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