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Phone ringtones 556 pairs timer principle explanation

2016-02-05 01:58  
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Next is the phone rings using 556 pairs  timer  principle explanation. The most effective way is to grasp the principle of combining schematic view text, combined with text to understand the principle. See Figure: circuit requires four unstable multivibrators for its work. Therefore two 556 ic here is how to use. IC 556 contains two timers (similar to 555 ICs) in a package. A person can also assemble this circuit using four separate 555 ICs. The first multivibrator generates a rectangular waveform with a second "low" "high" duration and the last time 2. This waveform is used to control the next multivibrator generates another rectangular waveform. A resistor R7 collector transistor T2 is used to prevent the capacitor C3 from being fully discharged when the transistor T2. Preset VR1 must be set at such a value that the two ring tones are heard second. The remaining two multivibrators are used to produce ringing tones corresponding to the ringing pulses generated by the multivibrator previous stage. When the switch S1 is closed, the transistor T1, thereby cutting off the first multivibrator generates a pulse start. If this switch is placed in the power path, you must wait longer, began ringing switch off. The circuit used is also apply for a driving voltage to the circuit began to ring. The principle is simple but effective. You can read several times to grasp the principle.

Telephone Ringer using 556 dual timers

Telephone Ringer using 556 dual timers

VN:F [1.6.9_936]

 


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