Cycling music call on a chip UMC-7-08
Quality modern plastic Bicycle bells, to put it mildly, leaves much to be desired. I propose to replace the regular Bicycle bell simple musical bell. If it is a kids bike, the call will cause the child a storm of delight. This call can be used as an apartment call with adjustable volume. Especially when you consider that overkill tunes in this call occurs randomly and, therefore, will not irritate the host.
In Fig. 1 shows a schematic diagram of the call.
Bell collected two chips. The A1 chip is a special chip to build a jukebox. In the memory chip hardcoded set of tunes that can be played back in sequence. In the chip UMC-08 three such melodies, as in chip UMC-08 eight of them are already. The difference is the inclusion of the chip from the standard  is that the choice of tunes is happening randomly. This is achieved by connecting an integrating chain across the resistor R1 and the capacitor C2 to the output 6 select a ringtone. When power is applied, the capacitor C2 is charged very slowly. At this time iím the first notes of all the songs.
At the time of charging the capacitor C2 begins to play the melody, the first note which coincided with this moment. Thus, when the power supply switch SA1 may include any tune. To walk through all of the tunes recorded on the chip, you need to choose the resistor R1. If you increase the capacitance of the capacitor C2 to 50-100 microfarads, if pressed briefly button SA1, the melody will sound or not, and are played the first notes of all the songs. As each note is played with a maturity and tact, it gives an interesting "cacophony".
The melody will sound as long as the button is pressed SA1. If the button is pressed more than lasts melody, it repeats. Chip A2 is the amplifier power up to 30 Watts per chip TDA1518BQ. This chip is chosen because of its prevalence and relative cheapness. It can be replaced without having to redesign the PCB chip TDA1516BQ. Preferably the chip to install a small radiator from aluminum plate. Stated in the reference material chips of 6 volts was fictitious, possibly due to Thai workmanship. In fact, the chip started to work at a voltage of 7.2 volts. Speaker B1 can be anything up to 4 Watts. But it must be remembered that current consumption will be different. When using an 8 Ohm speaker (Sistek sound master 1 w min 2 w max) maximum current was 0.5 A.
Because every note has its own frequency, the current consumption will be different when the sound of each note. In the pauses the current consumption was about 50 mA. To adjust the volume of sound is required before the power amp to supply the resistor 10, the shortfall of one end on the ground, and the second on capacitor C3. With engine resistor through capacitor 0.22 microfarads signal supplied by the amplifier. Power Cycling better to make a call from two flat batteries 3R12х. Food housing better to make a call from the stationary power supply. The printed circuit Board from one-sided fiberglass shown in figure 2.
Bicycle bell conveniently placed in a coconut shell. Approximately one third of the nut must be cut into the cutting circle. To cut the larger part of the shell by screws M2,5-3 screwed into a plastic plate with a speaker. Inside the nut clamps are attached to the battery. To the handlebars of a Bicycle bell mounted as a lamp by means of steel strips.