Belkin Tunecast II FM Transmitter Mod
It certainly sets you up as resident pirate radio DJ of your block and allows you to jam the loud radio listener on a bus or train!Please note that this nike shoes is a rehash of something that was done before 'instructable' came along. However I did not find the attenuation component. Today you can find very cheap and powerful fm transmitter on Internet from different countries where they have no law on fm transmitter power. Unless you really want to touch to the electronic which is not easy, you will gain time and have a way better fm transmitter by bying a cheap new one.
The Corrugator, this is a great Instructible!
I used a different method to boost the output power, which will work not only for the Belkin Tunecast, but for ANY transmitter which uses a BH1415F, or even any other Rohm FM transmitter chip. Instead of trying to figure out what components were involved in the filter/attenuation network, I used a soldering iron and a toothpick to lift and disconnect BH1415F pin 11 (RF output) from the board. Then I soldered a quarter wave wire antenna directly to the pin, which gives direct access to the maximum possible output power. Make sure the wire is secured so an accidental tug won rip the pin off the IC; I used a generous application of super glue to attach the wire to the board near the connection. If a transmitter uses a different Rohm FM transmitter chip than the BH1415F, look up the datasheet to find out which pin is RF output.
The real gold in this Instructable is the auto power off disable. I been using this transmitter to listen to music from my computer anywhere in the house, and have been looking for a good way to disable the auto power off. Up until now, I been doing it by running a separate copy of Winamp that plays a subsonic or ultrasonic burst for two seconds, every 30 seconds in a loop. It worked, but on some radios you could hear a slight distortion when the burst played. This may still be a useful option for people who aren comfortable soldering, or who have a different transmitter.
I just performed your auto power off disable mod, and it works great! Though I did make one change. The pad you getting power from appears to be active only once the transmitter is powered up, which still requires an initial audio input. So instead, I connected the transistor pin through a 1M resistor directly to the positive pin of the DC power jack. If you looking at nike shoes the board from the LCD side, with the power connector on the bottom, it the second pin from the left between the large SMD capacitor and the LCD (verify it with a voltmeter if you unsure you have the right one). The transmitter now turns on immediately when power is applied, and stays on indefinitely; regardless of audio input.
Finally, one more tip. Loop the power and audio input cables a few times through a ferrite toroid filters out hum and hiss. You can use one toroid, but it easier to use two, one for each wire. The more loops, the tighter the windings, and the closer to the transmitter, the better it works. A clamp on style ferrite should work almost as well, though I haven tried. Obviously, don loop your antenna through a ferrite, as this will attenuate the signal. If you haven added your own separate wire antenna, skip the toroid for the audio cable, as it contains the antenna.
With these changes, I very happy with the performance of this transmitter; and its range and quality rival any consumer or kit transmitter I tried for less than $100.
Wow, thanks for the generous updates and mods! I am sure somebody will find it useful too.
A bit about the Rohm FM chip. Before these iPods, many FM transmitters came in kit form, and the Rohm chip was the first to be highly integrated and made it easy to build these. And I think you could get single chip (with earphone amps) FM radio tuner too.
It is a great little FM transmitter isn it. In terms of fidelity, if you get it right, FM transmitter still kind of sound better than Bluetooth speakers. nike air max 90 Heh, kind of please there still a purpose for this old instructable. Cheers!
Good and clear instructions but my layout is a bit different, with what I think to be the inductor vertical instead of horizontal.
I tried a reception test just touching a contact attached to a wire to various components (starting from what I think was the chip side of the inductor) but could not improve reception.
The only thing that did was the lower right pin of the chip on the rear (marked 1 on first pic below), so I soldered my wire to that. Now I get reception up to about 25m away through several brick walls (having got about 5m out of the box if I was lucky). My wire is about 1.5m long, and I didn experiment for the optimum length, as it works (and this is to be used inside a house anyway).
As for the auto power off mod, that went wrong too! I fluffed the solder a bit to the top right contact point, and it seemed to disappear leaving no metal to contact. Doh! After a bit of experimentation, I found that the same lower right leg of the other component (marked 2 in pic below) when jumpered to the resistor right next to it (marked 1 in pic) put the Tunecast into an always on state. I settled for that, as again this is to nike air max 90 be used in the home, it only uses about 2w, and I am powering it from a transformer anyway so I don have to mess about with batteries.
Just did this mod, on another board.
The first experiment was to extend the antenna. I cut the blue antenna line at 2cm. Soldered a line of 80cm to it. Result: worse than the original tunecast2.
Second experiment: I removed the old antenna (just ripped it off) and soldered a new line to the board on another position, see picture below. Much better result than my first experiment, however, I cannot tell if it better than the original tunecast2.
Please do not laugh at my soldering technique/result, I not very good at this i afraid : )
Third experiment. Note that this step cannot be undone. Using a knife, I cut away that small white thing below my new antenna. It did not seem to make things better or worse. I forgot to make a picture of this, and currently I too lazy to reopen the device and take a picture
Tomorrow I drive 200+km and will let you know if it made things better or not. 56th St., tried to dupe Customs officials by mislabeling the shipments of coffins and other artifacts as and panels, according to an indictment unsealed in Brooklyn Federal Cheap Christian Louboutin Court.
It certainly sets you up as resident pirate radio DJ of your block and allows you to jam the loud radio listener on a bus or train!Please note that this nike shoes is a rehash of something that was done before 'instructable' came along. However I did not find the attenuation component. Today you can find very cheap and powerful fm transmitter on Internet from different countries where they have no law on fm transmitter power. Unless you really want to touch to the electronic which is not easy, you will gain time and have a way better fm transmitter by bying a cheap new one.
The Corrugator, this is a great Instructible!
I used a different method to boost the output power, which will work not only for the Belkin Tunecast, but for ANY transmitter which uses a BH1415F, or even any other Rohm FM transmitter chip. Instead of trying to figure out what components were involved in the filter/attenuation network, I used a soldering iron and a toothpick to lift and disconnect BH1415F pin 11 (RF output) from the board. Then I soldered a quarter wave wire antenna directly to the pin, which gives direct access to the maximum possible output power. Make sure the wire is secured so an accidental tug won rip the pin off the IC; I used a generous application of super glue to attach the wire to the board near the connection. If a transmitter uses a different Rohm FM transmitter chip than the BH1415F, look up the datasheet to find out which pin is RF output.
The real gold in this Instructable is the auto power off disable. I been using this transmitter to listen to music from my computer anywhere in the house, and have been looking for a good way to disable the auto power off. Up until now, I been doing it by running a separate copy of Winamp that plays a subsonic or ultrasonic burst for two seconds, every 30 seconds in a loop. It worked, but on some radios you could hear a slight distortion when the burst played. This may still be a useful option for people who aren comfortable soldering, or who have a different transmitter.
I just performed your auto power off disable mod, and it works great! Though I did make one change. The pad you getting power from appears to be active only once the transmitter is powered up, which still requires an initial audio input. So instead, I connected the transistor pin through a 1M resistor directly to the positive pin of the DC power jack. If you looking at nike shoes the board from the LCD side, with the power connector on the bottom, it the second pin from the left between the large SMD capacitor and the LCD (verify it with a voltmeter if you unsure you have the right one). The transmitter now turns on immediately when power is applied, and stays on indefinitely; regardless of audio input.
Finally, one more tip. Loop the power and audio input cables a few times through a ferrite toroid filters out hum and hiss. You can use one toroid, but it easier to use two, one for each wire. The more loops, the tighter the windings, and the closer to the transmitter, the better it works. A clamp on style ferrite should work almost as well, though I haven tried. Obviously, don loop your antenna through a ferrite, as this will attenuate the signal. If you haven added your own separate wire antenna, skip the toroid for the audio cable, as it contains the antenna.
With these changes, I very happy with the performance of this transmitter; and its range and quality rival any consumer or kit transmitter I tried for less than $100.
Wow, thanks for the generous updates and mods! I am sure somebody will find it useful too.
A bit about the Rohm FM chip. Before these iPods, many FM transmitters came in kit form, and the Rohm chip was the first to be highly integrated and made it easy to build these. And I think you could get single chip (with earphone amps) FM radio tuner too.
It is a great little FM transmitter isn it. In terms of fidelity, if you get it right, FM transmitter still kind of sound better than Bluetooth speakers. nike air max 90 Heh, kind of please there still a purpose for this old instructable. Cheers!
Good and clear instructions but my layout is a bit different, with what I think to be the inductor vertical instead of horizontal.
I tried a reception test just touching a contact attached to a wire to various components (starting from what I think was the chip side of the inductor) but could not improve reception.
The only thing that did was the lower right pin of the chip on the rear (marked 1 on first pic below), so I soldered my wire to that. Now I get reception up to about 25m away through several brick walls (having got about 5m out of the box if I was lucky). My wire is about 1.5m long, and I didn experiment for the optimum length, as it works (and this is to be used inside a house anyway).
As for the auto power off mod, that went wrong too! I fluffed the solder a bit to the top right contact point, and it seemed to disappear leaving no metal to contact. Doh! After a bit of experimentation, I found that the same lower right leg of the other component (marked 2 in pic below) when jumpered to the resistor right next to it (marked 1 in pic) put the Tunecast into an always on state. I settled for that, as again this is to nike air max 90 be used in the home, it only uses about 2w, and I am powering it from a transformer anyway so I don have to mess about with batteries.
Just did this mod, on another board.
The first experiment was to extend the antenna. I cut the blue antenna line at 2cm. Soldered a line of 80cm to it. Result: worse than the original tunecast2.
Second experiment: I removed the old antenna (just ripped it off) and soldered a new line to the board on another position, see picture below. Much better result than my first experiment, however, I cannot tell if it better than the original tunecast2.
Please do not laugh at my soldering technique/result, I not very good at this i afraid : )
Third experiment. Note that this step cannot be undone. Using a knife, I cut away that small white thing below my new antenna. It did not seem to make things better or worse. I forgot to make a picture of this, and currently I too lazy to reopen the device and take a picture
Tomorrow I drive 200+km and will let you know if it made things better or not. 56th St., tried to dupe Customs officials by mislabeling the shipments of coffins and other artifacts as and panels, according to an indictment unsealed in Brooklyn Federal Cheap Christian Louboutin Court.
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