Our musical bell plays a few tunes. Can be used as alarm clock. The "heart" of the call can be wrist alarm clock MONTANA. Watches must be removed from the housing, Unscrew the screws, holds charge with indicator light, thin conductors to solder the output according Fig.1 and then re-pin card.
These findings connect with the watch the circuit shown in Fig.2.
The operation of the circuit and the functions of the elements. The audio frequency amplifier is made on the elements R2, VT1, VT2. Trimmer resistance R1 set volume sound. The capacitor C1 prevents the power consumption of the amplifier in expectations. Diode Assembly VDl, VD2 required for concurrent filing a positive pulse to pin 1 (DATE) and 2 (ALTM). The fact that enforce the melody in hours by simultaneously pressing two buttons DATE and ALTM. In hours no lock playing the melody. Therefore, when frequent taps of the bell button changing tunes will occur randomly.
To prevent this from happening, in the scheme introduced elements C3, VD3, R3, VD4, C4. When pressing the bell button (contacts K1, K2) of positive momentum flows through capacitor C3 and diode Assembly VD1, VD2 on pins 1, 2 hours. After you start playing the melody sound frequency is supplied to the capacitor C3 and charges it. Charged the capacitor does not pass a positive pulse from the contact K1. Thus, call while playing the melody will not respond to button presses K1, K2.
After the end of the melody discharge circuit VD3, R3 discharges the capacitor C3, preparing to receive the next signal. If bell button (K1, K2) do not let go, then the capacitor C3 is discharged and the call will transfer to expectations. Continuous playing music will not. Capacitors C2, C5 protect the call from false alarms that may be triggered transients induced in the wire connected to the contact K1.
Food call offline (two batteries type R-20). Clock feed voltage of 1.5 V, and the amplifier - V. 3
The maximum power consumption occurs during play the melody. In standby mode, energy is consumed only for the maintenance of the clock. Practically in this mode, the battery life determined by their own self-discharge. Button SBl (ALTM), SB2 (DATE), SB3 (MODE) are used to control the clock. To call did not work independently in case of coincidence of alarm time with the current time, it is necessary to enable the alarm clock symbol will disappear) and set the clock in the stopwatch mode. Tunes will be included, and the clock - no.
In brand watches MONTANA a number of melodies and sounds are different. This gives the ability to change ringtones replacement hours. The call is assembled in the case of a subscriber speaker, clock and button displayed on the front panel.
Author: S. M. Usenko, Chernihiv region