| Author | Message | ||
     mc |
i read the section on build a simple am radio transmitter and i would like to know if there are any other good website which show how to build a fm radio transmitter and be able to change the station it is broadcasting to | ||
| Simon Quellen Field (Sfield) |
You will find lots of information if you use Google and type in simple fm transmitter or low power fm transmitter | ||
| Gregory |
I tried to make the AM transmitter but I couldnt get it to work. I cannot figure out what was the problem. Maybe my problem was that I did nothing with the black lead of the audio transformer. Another possible, but I don't expect it because it looked pretty sound was the soldering connections. I have just started soldering recently. :-{O When I hold the antennae of the transmitter, to the antannae of the boombox (tuned to 1000 AM) all I could get was crackling, if it was close or touching. Instead of alligator clips I used hookup wire from radio shack and I soldered clips to them. I hope that you will be able to find my problem because I am really excited about having a transmitter. I am constently amazed by the promptness of your replies, how do you do it? | ||
| Simon Quellen Field (Sfield) |
First, make sure the oscillator is not put in backwards. There are two ways it can go, and only one is right. One corner of the can is sharp, and the other three rounded. The pin nearest the sharp corner is not to be connected to anything. The middle wire of the transformer is not to be connected to anything. Turn on the boombox. Now plug the battery into the transmitter. If the static in the boombox goes quiet, then you are transmitting a carrier. If it does nothing, then check the power connections to the oscillator. You can also try using 5 volts or 6 volts instead of 9, in case the oscillator you have is an old TTL version instead of a modern CMOS version that can handle the extra power. The ones we sell in our catalog are guaranteed to work in this application. If the oscillator is working (as evidenced by the quieting of the static) then you need to check the modulation. Is your audio source designed to operate an 8 ohm earphone? If it is designed for 16 or 32 ohm headphones, it will probably not work very well. You can try raising the volume control on the radio you use as the signal source. Do you have a good ground connection? A Cold water pipe is good, and usually the metal case of a computer is grounded through the third prong of the power supply cord. Let us know how you make out. | ||
| Anonymous |
hello, I would like to know what you mean by the metal case is it the back of the computer? | ||
| Simon Quellen Field (Sfield) |
Any metal you can touch on the outside of the computer is probably grounded. But if you are in doubt, use a cold water pipe. | ||
| gregory |
I still cannot figure out what is wrong with the transmitter. I think the problem was with the soldering because with the audio jack, I cheated with the soldering and picked up a blob of solder with the soldering iron and then placed it in posistion. I'm pretty sure that my components are right because I either bought from the catalogue or I used the part number from radio shack. I noticed that you added a going farther section at the top of the transmitter page, but it was not a link. What is it about? | ||
| Simon Quellen Field (Sfield) |
Can you hear any change in the sound from the boombox when you apply power to the oscillator? With the power applied, can you hear any change in the sound when you connect the two transformer wires together (thus causing a short circuit, so the power goes directly to the oscillator instead of going through the transformer first)? If you never hear any difference after doing those things, then the problem is with the oscillator. If you hear the static get quieter, then the oscillator is OK, and the problem is with the transformer, the connections, or the signal source. | ||
| Robert |
One thing, isnt it dangerous to attach a ground cable to the earth pin of you power cable? cus i had a dick smith crystal radio project and it said NEVER conect the earth to the earth pin of the power supply sunce it something went faulty you would ge zapped! | ||
| Simon Quellen Field (Sfield) |
The crystal radio does not have a power cable. The transmitter project uses batteries. The ground connection of a wall plug is connected to a big spike driven into the earth where the power enters the house. This should be the only connection to the dirt in house wiring. What we wish to avoid is a path from high voltage to Mother Earth that passes through you. The ground pin on the power cord should be connected to that one good grounding spike, so that it is the best path to ground. Crystal radios need a ground connection to work. But since they don't need power, there is no reason to get near a power cord. | ||
| Anonymous |
i built the am transmitter and connected the phone jack to a old record player and connected everything how its supposed to when i connected the 9 volt battery and played a record i couldnt hear anything on the radio and for some weird reason the plastic on the transformer started to melt what went wrong did i use a transformer to small? did the transformer overload because the recordplayer? | ||
| Simon Quellen Field (Sfield) |
It sounds like you were putting too much power into the transformer. The record player may have been turned up too far, although at this point we can't rule out wiring errors. You may have damaged the oscillator in the process. You can test this by powering the oscillator on and off, and listening to the radio to hear the clicks. If the static goes away when the oscillator has power, then it is fine. | ||
| Anonymous |
about the middle plug of a power cord, i believe you friend was thinking of how the ground is tied to the neutral wires in the house, but since the wires are still atached to the ground, they should not have any voltage. the ground wire may have some ripple comming from any other electronic gear in the house, which may affect the transmission quality of the transmitter. Always be careful when sticking anything metal into an outlet, regardless of what part | ||
| saranya Unregistered guest |
I would like to know what the circuit diagram and the components required for an fm transmitter is and how we can make a simple one as a project. Thank you. | ||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 79 Registered: 12-2004 |
I may decide to do such a project, but in the meantime, there are many simple FM transmitter circuits on the web and in your library. Just do a Google search for "simple FM transmitter". | ||
| koby Unregistered guest |
I would like to know what the circuit diagram and the components required for an fm transmitter is and how we can make a simple one as a project. Thank you. | ||
| Simon Quellen Field (sfield) New member Username: sfield Post Number: 150 Registered: 12-2004 |
How many times in this thread do I have to tell people that there are LOTS of FM transmitter circuits on the web already, and a Google search will find them in a second or two. Some day I will add an FM transmitter project here if I feel I can do a better job than those other sites, or if I have some unique twist. But until then, there are lots of very good sites that show how to do this. | ||
| Heather Unregistered guest |
I don't know if this is the right sight for this question but I need some help. We have a TV with no head phone jack. My question is how do I convert the 8 ohm output circuitry to a 32 ohm impedence jack for head phone use? (or does it matter?) Anybody have an answer? | ||
| nicholas (Unregistered Guest) Unregistered guest Posted From: 66.61.14.95 |
If I have a vintage radio with no power cord, how can I check, without changing the cord, if the radio still works? Is there someway I can use an alligator clip hook-up to give it power. If so ,how? Thanks | ||
| Syed Haider Abbas (Haider_abbas) Member Username: Haider_abbas Post Number: 11 Registered: 12-2007 |
Hi Simon, In computer controlled radio project you have written that replace the oscillator by a 28.322mhz oscillator can i use the 28.322 oscillator in simple AM voice transmitter if i can use,can i have to change the power by using two 9 volt batteries.I have to enter in science fair with this project so i don,t want the ground wire because there is no good ground in exhibition hall. So please give me the right information. I shall be thankful to you | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1835 Registered: 12-2004 |
If you don't have a receiver that can receive AM transmissions at that frequency, you won't be successful. The reason we use 1.0 Mhz is that AM receivers for that frequency are cheap and ubiquitous. | ||
| Syed Haider Abbas (Haider_abbas) Member Username: Haider_abbas Post Number: 13 Registered: 12-2007 |
Hi Simon, I have to ask that can i make transmission range longer by a long antenna and if not then i cannot understand why you have written in computer controlled radio project that replace the 1.000mhz oscillator with a 28.322mhz oscillator. That are just some questions the main problem is of ground wire of AM radio transmitter and of frequency range. So tell me the solution of ground wire and that i can make the transmission range longer by a long antenna. So please tell me the right information. I shall be thankful to you. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1836 Registered: 12-2004 |
28 Mhz is in the 10 meter band. That makes it legal to use if you have an amateur radio license. Having a license means you can use a bigger antenna. In this case, it meant using a 14 element beam antenna, a highly directional antenna that aims almost all of the energy in one direction, like a spot light. In addition, that frequency bounces off the ionosphere to curve around the earth. Lastly, an extremely sensitive communications receiver was used, with very narrow band filters, and slow morse code was used, which has a much smaller bandwidth (and thus a much greater signal to noise ratio) than AM. You don't have the receiver, or the license, or the special antenna, and you are using amplitude modulation. Stick with 1.0 Mhz. Electronic equipment with metal cases are almost always grounded. If you need a ground connection in an exhibition hall, connect the wire to the metal case of a computer that is plugged in. | ||
| Syed Haider Abbas (Haider_abbas) Member Username: Haider_abbas Post Number: 16 Registered: 12-2007 |
Hello Simon, I cannot understand the term piezoelectric earphone or piezoelectric just explain me that what is piezoelectricity, I cannot get the piezoelectric earphone what replacement i can use instead of piezoelectric earphone in a very simple radio. May i connect the ground wire of very simple radio to the turned on computer. Science fair is coming. So please give me the right information. I shall be thankful to you. | ||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 1838 Registered: 12-2004 |
Google is your friend: "http://www.google.com/search?q=piezoelectricity" "http://en.wikipedia.org/wiki/Piezoelectricity" Ground is ground. Any ground will work. | ||
| Syed Haider Abbas (Haider_abbas) Member Username: Haider_abbas Post Number: 17 Registered: 12-2007 |
Hi Simon, Can i expand the the range of the simple AM transmitter by using a long FM antenna and if yes how much its range will improve. So please give me the right information. I shall be thankful to you. | ||
| Jacob Morrison (Unregistered Guest) Unregistered guest Posted From: 71.51.44.237 |
Help I purchased the am transmitter kit and I cannot seem to get it to work, I have switched the input sources please help. Is it normal for the oscillator to get hot "once it warms I disconnect the battery" Please help Jacob |
