A three-tone ringer

I have a small company whose premises consist of two long wings of the building and everything is served by three entries spread: Well now, thanks to the editing that I'll offer you, the employee assigned to receive recognition "to ear "in which someone has just three entries sound, in fact, the bell button of each entry determines" its "own sound.
I designed the circuit has definitely solved the problem that arose before and that everyone can easily guess: each entry is associated with a different sound and we know where the person presents.
To achieve this I used a unijunction transistor 2N2160 in metal case that I paid just one euro in a retail electronics. The wiring diagram of Figure 1 shows that by pressing one of three buttons P1-P2-P3 is connected to the emitter of transistor UJT1 resistance of different value each time R1-R2-R3, with the ability the capacitor C1 of 220 nF each determines a different frequency. Three notes 150-480-1 500 Hz
If you want to make the higher notes, just reduce the ability of C1 and if you want to change the frequency of a single note, change the value of the corresponding resistor connected to the transmitter.
Initially, to find a note that suited me, I replaced the three by three resistors 22 k trimmers ... and I turned their axes until you find the "good" rating for each of the three "channels". Nothing prevents them then leave.
Now we must decide what final stage up to drive a small speaker. For my part I took your edit EN1306: This small amplifier integrated circuit (see Figure 3) gives a power of 1 W and can also take the EN1307 provides 5 W (see Figure 4). The volume pot of EN1306 R1 works by making the mass a more or less of the resistor connected to pin 4 of integrated circuit of Figure 3 or pin 5 of that of Figure 4. Both models of amplifiers feeding into 12 V.

Figure 1: Electrical generator circuit notes.

Exits ABC are right to connect to the inputs of the amplifier ABC chose, that of Figure 3 (1 W) or that of Figure 4 (5 W).

Component List
R1 ..... 18 k
R2 ..... 5.6 k
R3 ..... 1.8 k
R4 ..... 330
C1 ...... 220 nF polyester
UJT1 .. 2N2160 unijunction
P1 ...... push
P2 ...... push
P3 ...... push


Figure 2: Assignment of the integrated circuit TDA7052 / B seen from above, the transistor UJT 2N2160 (he has two bases B1 and B2 and no collector) from below and the integrated circuit TDA7056 / B front view.
Figure 3: Diagram of the amplifier EN1306.

This amplifier provides a power of 1 W, it is available with its printed circuit board.


Component List
R1 ..... 1 million pot. flax.
C1 ...... 470 nF polyester
C2 ...... 100 nF polyester
C3 ...... 220 uF electrolytic
C4 ...... 100 nF polyester
IC1 ..... TDA7052 / B
HP ..... Speaker 8 ohm

Figure 4: Diagram of the amplifier EN1307.

This amplifier provides a power of 5 W, it is available with its printed circuit board.


Component List
R1 ..... 1 million pot. flax.
C1 ..... 470 nF polyester
C2 ..... 100 nF polyester
C3 ..... 220 uF electrolytic
C4 ..... 100 nF polyester
IC1 .... TDA7056 / B
HP ..... Speaker 8 ohm


Editor's Note
We have nothing to add other than (for newbies) that the generator circuit of notes in Figure 1 receives power from one of the two amplifiers of Figures 3 or 4 (who themselves need an external power 12 VDC 1 A
The reader can perform the assembly of Figure 1 for a perforated plate pelletized or bands.