| Author | Message | ||
     ABCinventor |
i couldn't find the phone plug EXACTLY the same as yours but i managed to find the same model but it has 3 pins, the other 2 pins is the same.I was told that it was for 2 earphones. I build the transmitter as told in the site, and i pluged the phone plug to the CD player the same order as the blue and green wire. i then tune my radio to 100 X10k Hz. there is a very soft pop song even if i adjusted my CD player and radio volume to the max. then i touched the third wire from the phone plug and the volume got louder. but i have a wierd feeling in my hand when holding the wire as if i am having a electrical shock. Please help me with the problem. This site is cool!!! but it should get a little more detailed... | ||
| Simon Quellen Field (Sfield) |
You are using a stereo phone plug instead of a monaural phone plug. Check the output impedance of your CD player. Not all of them are designed to use 8 ohm earphones. Some use 16 or 32 ohm earphones, and will not modulate the transmitter well. Try different audio sources. You will also get better results with a longer antenna and a good ground connection (connect the negative side of the battery to a cold water pipe). | ||
| ABCinventor |
Well... after checking and testing, it seems that it it using me as the "earth" wire(the "ground"). after modifications, the problem is solved but still, the sound coming out of the radio is not very loud... so now i have a problem. i am using a transformer that reads 0V,115V,230V on one side and 9V,0V,9V on the other side.on the top, it says 0.3A . Am i using the right transformer or should i change one?? i have been to the radio shacks in my country but they all tell me that transformers are measured by voltage, not ohms...i doubt that there is something to do with the transformer that affects the volume. please give me some explanations.Thanks Simon!!! | ||
| Simon Quellen Field (Sfield) |
You are confusing a power transformer with an audio transformer. If you are having trouble finding an audio transformer, try here. | ||
| ABCinventor |
Oh so mine are power transformer, not radio... but it still works quite ok except that the volume is about normal speech volume. i would like to buy from your catalog, but i dont have a credit card and buying from a radio shack is cheaper. well there are plenty of radio shacks in Singapore so i will try to look for them there first... even so finding a radio transformer may be difficult also as in my country, radio transformers are not common. i even have trouble searching for 1MHz oscillators . the more common ones are the 1.8432 MHz ones. but in the end i finally found the 1MHz oscillator. if i couldn't find them i will definitely get it from you!!! | ||
| ABCinventor |
Oh one more question. Why do we have to connect the negetive to the Earth to get a good connection?? | ||
| Simon Quellen Field (Sfield) |
Why grounding the transmitter increases the range is a complicated thing to explain and understand. However, a very simplified explanation is to think of the earth as a mirror for the antenna, making the antenna seem to be twice as large (because the receiver gets the signal from the antenna and the reflection). Also, when looking for the transformer, remember to ask for an audio transformer, not a radio transformer. Audio, radio, and power are all three different types of transformer. | ||
| ABCinventor |
I've just been to the radio shacks and almost all of them only sells power transformer. when asked about transformer, many of them replied that transformers are measured in voltage. asked about ohms and they said that there are either no such things or they don't sell it. only one radio shack that i have been to sells transformers measured in ohms but were far beyond the needs of the transmitter. they were 0,4,8 (ohm)on one side and 0,5k,10k(ohm) on the other side and 0,4,8(ohm) on the side of ther other transformer and 0,3.5k,7k ohm) on the other side.So i bought a small one measruring 1 cm by 1cm by 1cm with 3 pins on one side and 2 pins on the other side. i am not sure if it's a power or audio transformer but i think the number of coils in the pri inducer and sec inducer is of little diference. Even if i bought the wrong kind, it doesn't matter because it cost Sin$0.80 or US$0.47. | ||
| ABCinventor |
After checking and testing the new-bought transformer, i concluded that the 9V power transformer produces a louder sound than the 1X1X1 cm transformer... Seems like the 9V power transformer is better.. | ||
| Simon Quellen Field (Sfield) |
The reason we carry the audio transformer in our catalog is because we got email from people all over the world who couldn't find the part locally, or who thought that clerks at Radio Shack knew something about electronics. | ||
| ABCinventor |
Simon, my friend and i would like to post a project that we had made last year during the holidays. it is a water rocket launcher that lunches soda bottles into the air to an alttitude of about 15 metres (MAX). the energy comes from a hand pump. with every strokes, more air is inserted and compressed into the launcher and eventually, the rocket shoots right up into the sky. but because it is a prototype, it is not very perfect. during pumping, a person has to hold the tip so that the bottle doesn't shoot out before it is being pumped to the optimum pressure. also because the tip of the launcher is a little smaller than the mouth of the bottle, we have to fix it with a few rounds of masking tape. there is a sharp aluminium rod that allows it to be inserted into the ground and operated with a single man but more masking tapes have to be used to make the bond stronger for the optimum pressure. |
