The google trick with Silicon Chip doesn't work for me anymore, I think they may have fixed the bug. Hi audio, I think before moving on I should see the datasheet of BH I tried on google but surprisingly didn't get to one If u have found it's datasheet plz supply me the link Silicon Micromitter IC is surface mount
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The FM02 is a two board FM transmitter. It accepts a stereo audio source and outputs a stereo FM broadcast signal on the frequency shown on the LED display. It comes just as shown in the picture above. It is rated at 30mw that's milli-watts of transmission power. For most Christmas DIYers this is a nearly perfect amount of power. Why is this good? Skip to this section for more details: [ FCC Rules ].
The FM02 is not a complete unit ready for use. Instead, it bridges the gap between an out-of-the-box solution, and a build-your-own unit that starts with a bare PCB and a bag of parts. PLL keeps the transmitter locked into the designated transmitting frequency without it drifting up or down.
The second key feature is the fact that the transmitting frequency is maintained even after power is turned off and back on. The FM02 is a very sophisticated assembly. Building a unit of this capability and size would be nearly impossible for most DIY'ers. So, to create a usable FM transmitter, the FM02 needs some help. The builder of the transmitter will take the FM02 and use it as the corner stone of a complete transmitter.
Data Sheet. The trick with this warranty is that it requires the product to be returned for repair to VAST in China. IF you can catch a group buy in progress on doityourselfchristmas. You can also receive warranty service from the units purchased directly from www. A gallery of over 25 different installations with pictures and 'how to build notes' is available. Do NOT power it up without an antenna. You don't need to have your 'real' antenna ready for this.
This will dissipate the RF energy just fine. Just be sure you don't enlarge the hole inside the BNC. If you aren't sure, then ask for help in the forums. Use a meter to check the voltage first. If all you have is a wall-wart that is labeled 12V, then that is most likely NOT regulated. A simple test of the output voltage with a meter will tell the tale.
While the unit will 'run' on the voltages noted above, you should try to run it on 12V. If you operate the unit at a reduced voltage, this only drops the mean voltage feeding the chip and thus drops the chips ability to function correctly. By turning down the operating voltage, that is one way to reduce that hissing pilot level , but your also reducing the correct operating voltage for not just the FM chip, but the microprocessor, the PLL, the display, the final RF amp, the whole thing, not to mention reduced range and added distortions in the audio paths within the TX and FM chip itself.
A good example of this is taking a portable battery operated radio and put a weak battery in it and hear how distorted and low volume the audio is compared to a fresh correct voltage battery. Many folks will experience some HUM in the transmitted audio. This is normal. The good news is that you should be able to eliminate this hum with the use of a Ferrite Bead. See the Ways to improve the sound quality for Advanced Users Section below if you hear a 'shhhhhhhhing' sound. If you look at the tech that is already in your house, you will see these beads on lots of things.
They are in power cords, and even ethernet cables. I get mine for free this way. I just cut them out of these cords. They usually have dozens of extras laying around. As far as size, you want to be able to wrap the wire through the hole and around the perimeter 3 times for maximum effect. You also need to wrap it tightly and secure it in place with a nylon tie wrap.
So, it depends on the size of the wire that comes out of your wall wart, you need to have a diameter that can fit three wraps of the wire and the tie.
If you use a Wall Wart for power, you absolutely need a ferrite bead on the power cord coming out of the wall wart. NOTE : it never hurts to put one or more ferrite beads on your cables. They may or may not eliminate your HUM , but they never make it worse.
The FM02 has a standard 3. There is one key point about the audio. It works best with a line level audio input. Line Level is a very low volume level signal. The Volume level on your PC needs to be set very low, barely audible. If you overdrive the audio signal, it will result in a FM transmission that will sound distorted.
This document shows the electronic board schematic and the PCB layout for the main transmitter board. The second board has the same physical outline dimensions. It also lines up with the 4 corner mounting holes.
Here is a pdf file that contains a scale outline that will serve as a template for the display board. You would use this to create your own bezel if you want to dress-up your installation: [ Bezel Template ]. The FM02 has an antenna connection that will look a bit unusual to most folks. It is known as an SMA type of connector.
Reference: Wiki entry for SMA connector. The outer part of this connector is a 'press-fit' part. It is possible to simply defeat the resistance of the press fit and cause this part of the connector to fall off!
The converter shown below will correctly hook to the FM SMA is the smaller gold colored part of the connector. You can purchase the adapters from diyledexpress. You will need to buy or make an antenna. There are MANY different designs for antennas. A large number of DIYers have made a type of antenna known as a dipole.
This is an easy to make antenna that will serve almost anyone's needs. Here is a link to a pdf with instructions to make your own: How to Make a Dipole Antenna. More recently, DIYC member Jhinkle published a paper for an antenna design that is easier to build with very good transmission characteristics. Here is the link to a posting on the subject. DIYC discussion thread You can go directly to the excellent design and build paper at this link: pdf paper for a ground plane antenna.
This is real simple, go to this website and find a frequency that is unused. If there are no unused frequency's, then pick one that is not very powerful and get your radio out and check it out. If you can't pick up any radio stations at your house, odds are no one will complain when you start broadcasting on that frequency.
NOTE: There are seasonal radio stations. A open frequency in June may be used in December. You should plan accordingly.
NB: Vastelec told U. New old stock and used FM02s may be available. They are usually stocked at Radiant Holidays. Was WLC Ventures. These come up as group buys on the DIYC forum from time to time. The red spot is a section of the PCB that was scrapped away revealing the copper. This is used a a soldering point for the ground. Two capacitors are needed as noted. This optional modification is noted on the pira mini-RDS datasheet, but not implemented on the mini-RDS board from pira:.
It's real simple: Do not transmit on a channel that is already in use by a commercial entity that can be heard in your location. The easiest way to do that is to not buy more transmitter then you need.
That is why the FM02 is such a good choice. Did you know if you use an FM transmitter the FCC can inspect your transmitter at any time without a search warrant?!! It's true. If the FCC finds you operating equipment that is in violation, you must give them your transmitter so they can destroy it! If you don't, you will face a large fine. Click here: FCC information for unlicensed operators.
Unlicensed operation on the AM and FM radio broadcast bands is permitted for some extremely low powered devices covered under Part 15 of the FCC's rules. On FM frequencies, these devices are limited to an effective service range of approximately feet 61 meters.
BH1415F IC. Datasheet pdf. Equivalent
Design of Stereo Frequency Modulation Exciter Controlled by Microcontroller