Guest Alun Posted February 26, 2005 Report Share Posted February 26, 2005 TV's are doulble insulated a earth pin is only required when an appliance has a metal case.Higer frequencies do mean more bandwidth,you can't modulate a 10KHz carrier with a 20KHz signal but you could modulate a 20MHz carrier with this 20KHz signal.prateeksikka,Yes high frequencies do mean short antennas but the antenna still needs to be on a very tall mast to achieve a long range. If you stand to a mountain you can see from 100s of miles and you can see a mountain from 100s miles away.I don't mean to have a go but I've already answered your question about high frequencies, did you even bother to read my previous posts?High frequencies are more prone to interferance and transistors and other components don't work very well at these frequencies, acept in infrared and optical band when LEDs and photo diodes work. - I'm not going to say this again. Quote Link to comment Share on other sites More sharing options...
MP Posted February 26, 2005 Report Share Posted February 26, 2005 I don't mean to have a go but I've already answered your question about high frequencies, did you even bother to read my previous posts?High frequencies are more prone to interferance and transistors and other components don't work very well at these frequencies, acept in infrared and optical band when LEDs and photo diodes work. - I'm not going to say this again. Alun,You should calm down. You did not need to say that. You are flaming, which is against the agreement to use the forum.For many members of this forum, English is not their first language. If they do not understand you, they will re-state the question. There is no cause to flame someone for this. In my opinion, the moderator of this forum should have deleted this post. Your sarcastic post would have been deleted in a forum I moderate soon after it appeared.MP Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted February 27, 2005 Report Share Posted February 27, 2005 OK, I'm sorry but I wish people would just say they don't understand me rather then just keep on asking me the same question over and over, - it's begining to annoy me. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted February 28, 2005 Author Report Share Posted February 28, 2005 hey alun and MP i am sorry!i read your earlier post which was pertaining to FM waves.actually i had by mistake put the same question of TV at another place in the same site,which i forgot to check!prateek Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted March 3, 2005 Author Report Share Posted March 3, 2005 HI ALL!CAN ANYONE OF YOU TELL ME THAT WHY IS A RADIO BAND-BE IT F.M OR A.M BROKEN?I MEAN IT IS NEVER CONTINUOUSI.E ALL FREQUENCIES ARE NOT PRESENT?PRATEEK Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 3, 2005 Report Share Posted March 3, 2005 Hi Prateek,He, he. My FM transmitter goes that far? ;DI am still tweaking my FM transmitter and frequently its output isn't modulated. It must be jamming radio station reception on FM radios with a "blank spot on the dial" all around me.I've got RF coming out of my wing-wang. It is all over my preamp, 'scope and DMM. Everything I measure has strong RF on it, even me!I don't know why your AM radio is jammed or broken. I'm not jamming it. I stay away from AM because it sounds lousy. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted March 3, 2005 Author Report Share Posted March 3, 2005 hi audioguru!sorry for it but i could not understand wat u said,i also fear u wronglyinterpreted my question.i meant that the frequency range 88-108 Mhzfor FM and 540-1600 kHz for AM.is not continuous.i.e all frequencies are not used by am broadcast.some frequencies are used by other applications alsowhy is it so?prateek Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 3, 2005 Report Share Posted March 3, 2005 Hi Prateek,I don't know why there are unused frequencies on your radio bands. My AM and FM dial is full of stations, some with different languages.I am having diffuculty finding a frequency to test the little FM transmitter I built a few days ago. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted March 7, 2005 Author Report Share Posted March 7, 2005 HI AUDIOGURU!WHILE SEARCHING ON THE NET,I FOUND THAT SOME OF THE SO CALLED MISSING FREQUENCIES ARE RESERVED FOR USE BY OTHER APPLICATIONS LIKE MILITARY ETC COMMENTS?U TOO SEARCH FOR A POSSIBLE REASON AND DO TELL ME IF U GET IT!PRATEEK Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 7, 2005 Report Share Posted March 7, 2005 Hi Prateek,In my country, the AM and FM broadcast bands are for the public, not the military.The military and others have their own bands. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted March 7, 2005 Author Report Share Posted March 7, 2005 hi audioguru!i must correct u on this point.in my country too ,F,M and AM bands are not used by army,the bands used by them fall into say 540-1600kHz which we vaguely called AM band (atleast in my country)but thats what i meant by my point earlier,540-1600 kHZ IS NOT F ULLY AM some frequencies are missing and those are used by army .actual AM is say(hypothetical)540-670690-880930-1600these are assumed and not actual values values falling out of this range used by militaryprateek Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted March 10, 2005 Author Report Share Posted March 10, 2005 hi audioguru!i had started this topic of FM wave propagation because i had recently built an FM RECIEVER AT MY PLACE ,.it was designed to operate at 220Vac which was followed by transformer,rectifier and filters etc.actually i had no transformer earlier when i was making it, out of curiosity,i connected only 4V dc (with fear in mind) after the filter directly and you wont believe,one of my electrolytic capacitors of 470uFexploded like a bomb! i changed it and put a 1000uF in its place i was shocked when i saw it exploding into pieces,however the circuit worked when i put the T/F in place and connected the mains supplyany comments on how it could happen?prateek Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 10, 2005 Report Share Posted March 10, 2005 Hi Prateek,Sure, backwards polarity from a high current supply is a good way to blow-up electrolytic capacitors. When I worked on the car-radio production line that's how they tested the anti-reversed-polarity protection diode. They put a heavy bucket over the radio and connected reversed polarity. We cheered each explosion a couple of times per day!You are lucky your radio's semiconductors weren't destroyed too. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted March 10, 2005 Author Report Share Posted March 10, 2005 I KNOW THAT AN ELECTROLYTIC CAPACITOR HAS A POLARITY!I AM SURE ON THAT POINT !I CONNECTED IT RIGHT AFTER ALL,I LOST 2 CAPACITORS IN2 HUGE EXPLOSIONS.NEITHER ARISES A QUESTION OF HIGH BIAS BECAUSE I WAS CAREFULLY INCREASING IT WHEN I REACHED JUST 4V IT EXPLODED WITH ALL MATTER COMING OUT OF IT.YMMMMMMMMCAN THE CAPACITORS BE FAULTY?PRATEEK Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 10, 2005 Report Share Posted March 10, 2005 I dunno.Reversed polarity is all I can think about that would explode caps with such a low voltage.I know! AC voltage at a high current explodes them too! Or DC with a high ripple voltage at high frequency.There is an inverter in our projects section that explodes its coupling capacitors. At first we thought it was because the caps are shown with backwards polarity. Then I realised that the caps have an extremely high AC current that is blowing them. The entire power of the inverter (70W to 100W) is going into those caps. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted March 17, 2005 Author Report Share Posted March 17, 2005 audioguru!though in any case i have only seen electrolytics caps explodingceramic capacitors just turn blackish if i apply high voltage across themprateek Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted March 18, 2005 Author Report Share Posted March 18, 2005 AND I MUST CONFESS I HAVE SEEN A VERY HIGH VOLTAGE CAPACITOR EXPLODE!IT IS ALMOST LIKE A BOMB WHICH CAN EVEN KILL.THE YELLOWISH PASTE COMES OUT WHICH IS REALLY HOT!!!!!PRATEEK Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 18, 2005 Report Share Posted March 18, 2005 Exploding tantalum capacitors are worse than electrolytics. Molten metal spits all over. Ouch! ;D Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted March 20, 2005 Author Report Share Posted March 20, 2005 hi audioguru!i think in my case i connected electrolytic capacitor with correct polarity but internally the polarity was reversed. i.e i put the blame on the capacitor manufacturer.is it fair enough as an explanation? how often is it the case?prateek Quote Link to comment Share on other sites More sharing options...
audioguru Posted March 20, 2005 Report Share Posted March 20, 2005 I never heard of a capacitor that has its polarity marked backwards, but I guess anything is possible. Quote Link to comment Share on other sites More sharing options...
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