steven Posted December 7, 2004 Report Share Posted December 7, 2004 :)well ive just completed my second big ear circuit . from my talking electronics magaqzine , and now ill post it for all to share . but first ill exsplain. it as best as i can . this is an fm transmitter type with the electret microphone of which is housed in a dish, originally, its a speaker horn type, with the speaker removed, now in this horn couver is still a long thunnel of which i have the mic in at the bottom, now if i dont use it if its not satisfactory enougth i can eliminate that and just use the bare bones horn cover, the electret microphone can be housed in a rubber ignition coil lead plug , it fits perfect and i used this idea before, anyhow all i have to do is switch it an and everything it hears, it will then transmitt it to the radio head set with ereal, tuned to a blank spot on the fm band , in this sitiuation tuneing into the fm big ear bug as it can be called is like tuneing to a short wave radio station where all the stations are so close on the dial that you caould easily miss the reception, but once you get it tuned right the sound reception is really good and clear , i once sat one on the tiolet shelf and while i was sitting in the lounge room with the radio heaset on i can hear the distant sounds of cars and barking dogs , of which enters through a small opening in the tiolet room cubicall , that small room acted like a reception dish, to and with the dish horn of the big ear again it made these sounds even clearer and louder to hear , even the gass baggers downstairs to, :) Quote Link to comment Share on other sites More sharing options...
steven Posted December 7, 2004 Author Report Share Posted December 7, 2004 :) Quote Link to comment Share on other sites More sharing options...
steven Posted December 7, 2004 Author Report Share Posted December 7, 2004 :)the circuit is simple to biuld on a prototype board and for the cirtcuit box, i replaced the used lid for one i made from pvc storm water pipes Quote Link to comment Share on other sites More sharing options...
steven Posted December 7, 2004 Author Report Share Posted December 7, 2004 :) :) Quote Link to comment Share on other sites More sharing options...
steven Posted December 7, 2004 Author Report Share Posted December 7, 2004 :) Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted December 10, 2004 Report Share Posted December 10, 2004 I have often wondered about antennas and I will try to explain what I think happens. Did you ever wonder how a cell phone antenna works when there is no ground. Or how an airplane antenna works. The reason I have wondered is becuase they show a ground based antenna in the drawings. The signal is applied to the antenna and it radiates with respect to ground. This looks to be the source of the radiation pattern. Up in an airplane, what is the radiation pattern when the antenna is way up in the atmosphere. The antenna is not the source of radiation because you need ground to propagate the signal. I believe that ground is relative in these situations as the power level is high. The radiation pattern of a cell phone is along the ground and your ground connection is the person holding the phone. In an airplane, the radiation pattern is also along the ground and it gets ground through the atmosphere and uses high power to transmit. It's all about the radiation pattern of the signal as it moves along the ground. Quote Link to comment Share on other sites More sharing options...
ante Posted December 10, 2004 Report Share Posted December 10, 2004 Hi Kevin,The fuselage of an airplane has the same effect as a car body when it comes to radio waves. You know the car isn Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted December 10, 2004 Report Share Posted December 10, 2004 And yet the radio eminates along a ground path. The radiation pattern of an airplane transmitter must be very large as you are so high up. As they transmit, the radiation pattern is still along the ground. Quote Link to comment Share on other sites More sharing options...
steven Posted December 11, 2004 Author Report Share Posted December 11, 2004 :)im haveing troubles in getting the bigt ear working again, this time the first one i biult went ok really good useing radio headphones to tune to it with but since then ive not botherd useing it again for a while so i biult the second one as shown ands it worked for a little but kept droping out and this time i used the digital radio with push buttons to try tune it, i got it ok for a short time as i herd my vioce comeing from the radio but it only went for a short time now i cant get my vioce over the radio again, so ill wait till i get a radio head set and try again Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 11, 2004 Report Share Posted December 11, 2004 Hi Steven,A digital radio relies on the excellent carrier frequency stability and accuracy of radio stations. Your transmitter's frequency probably drifts due to temperature and supply voltage changes so its signal drops-out. Use an analog radio with AFC. Quote Link to comment Share on other sites More sharing options...
steven Posted December 11, 2004 Author Report Share Posted December 11, 2004 i had the feeling it was the pushbutton digital radio as i only got it working for a short time, originally before i used an analoge radio head phones with ereal and it worked good but now there seems to be few and far between and i have to try find one again Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 11, 2004 Report Share Posted December 11, 2004 Hi Steven,I hope you don't have to make a complicated digital frequency synthesized transmitter just to match today's digital radios. Quote Link to comment Share on other sites More sharing options...
Dazza Posted December 12, 2004 Report Share Posted December 12, 2004 Hi, I made an FM stereo transmitter using the BA1404 and it works ok, but the sound quality is poor and my stereo has a hard time picking up the signal and its only about three metres away, if the single isn't strong enough or if there is any slight drift it will drop out, the stereo transmitter uses crystal lock, so my stereo must be very fussy on the stability of the signal it receives. I have no trouble picking up the signal with my clock radio which is quite a distance away, as well as my car stereo but the signal is week.These FM transmitters can be very touchy, I think using a transmitter with crystal lock in my experience is the way to go. Quote Link to comment Share on other sites More sharing options...
steven Posted December 12, 2004 Author Report Share Posted December 12, 2004 :)the first time i had the big ear working good was some time ago when i first biult it and the analouge radio headsets were great at picking up distant sounds really good and clear, even barking dogs ,cats to in the distance, but now i think ordering a parabolic mic circuit from jaycar will be more easyer than useing this big ear fm transmitter circuit, at least i can hear what it picks up through a pair of headphones rarther than rely on these sometimes unreliable fm transmitters, Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 12, 2004 Report Share Posted December 12, 2004 Hi Steven,Please post Jaycar's schematic for their parabolic mic circuit when you get it. Quote Link to comment Share on other sites More sharing options...
steven Posted December 12, 2004 Author Report Share Posted December 12, 2004 audio guru this page took a long while to come up ,when i clicked on reply, jaycar is www.jaycar.com.au to view there online catalouge. with bills to pay it would be a few weeks before i can order that kit of the parabolic mic , so as soon as i do ill upload or email you the circuit schematics for that kit. ive got everything together to biuld the amplified ear circuit so i hope it would do the same or similiar thing to, as it says it will enable you hear distant sounds to , ive got an electret mic setup useing a spotlight dish to help receave sounds and i used an ignition coil lead cup to hold the small electret mich in place, that rubber lead cup from the end of an ignition coil lead allso stops vibration i think and it helps to hold the mic in place in the reflecter Quote Link to comment Share on other sites More sharing options...
steven Posted December 12, 2004 Author Report Share Posted December 12, 2004 Quote Link to comment Share on other sites More sharing options...
steven Posted December 12, 2004 Author Report Share Posted December 12, 2004 oops ive uploaded the wrong circuit but i geuss it may come in handy Quote Link to comment Share on other sites More sharing options...
steven Posted December 13, 2004 Author Report Share Posted December 13, 2004 :)audio guru i got that other circuit working, the one that you recamend i put a 10uf electro across from pin 8 of the lm358 ic to pin one to increase the gain, well ill exsplain first, i decided to rebiuld it from scratch and it worked good before i put the 10 uf electro in and it still works good to and oicks up sounds really well through the electret mic fixed into a spotlight reflecter, now i want to sractch the 8 ohms speaker and use a pair of headphones to listen with so what changes do you recamend in order to use head phones instead of the speaker. and allso id like a good electret microphone amplifier or preamplifier to amplify the microphone reception. if you have any good simple circuits for any Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 13, 2004 Report Share Posted December 13, 2004 Hi Steven,It's good that you got your LM386 amp to work. The only thing I recommend for headphones is to add a 1K resistor across the output (where the speaker is connected now) to charge its output cap so if you ever plug the headphones in with the power already turned on, you don't hear a big bang.If you don't mind listening to the hiss from the LM386 with the 10uF cap added to boost its gain, then you don't need a good mic preamp. Quote Link to comment Share on other sites More sharing options...
steven Posted December 13, 2004 Author Report Share Posted December 13, 2004 thanks audio guru now i just need a headphone amplifier to amplify the output sound a good battery operated one Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 13, 2004 Report Share Posted December 13, 2004 But the LM386 IC will be a fairly good battery-powered headphones amp, especially if you use a quiet preamp with it if you don't like its hiss.There are some headphones amp projects on the web called Headbanger and Super-Headbanger. They are battery-powered and use LM386 ICs. They are rated pretty good. They use negative-feedback around the output cap to extend its bass response and reduce its bass distortion. You don't need the extra feedback for your parabolic mic, unless you want to clearly hear the guy 3 streets away play his drums. ;D Quote Link to comment Share on other sites More sharing options...
steven Posted December 13, 2004 Author Report Share Posted December 13, 2004 :)audio guru ive seen that head banger site but when i look at circuits the first thing that gets me is some of the parts are hard to get and ive never herd of some Quote Link to comment Share on other sites More sharing options...
ante Posted December 15, 2004 Report Share Posted December 15, 2004 Hi Guys,How come this thread shows up twice the width of my screen?? Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 15, 2004 Report Share Posted December 15, 2004 Your screen shrinks from waiting so long for this site to load. ;DAfter I hit "reply", I ate lunch, watched some TV shows and even built half a project. I had a look and it still didn't finish loading. So I washed my car in the freezing cold outside. With my glasses all fogged-up, I typed this. Now I gotta wait again for it to post. Oh, man!Maybe the site is overloaded from Steven posting his "big ear" in so many topics! Maybe John's cardboard "bull-horn" overloaded it![move] ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D [/move] Quote Link to comment Share on other sites More sharing options...
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