Posts Tagged ‘buzzer sound’

Door buzzer sound with CD4001 CD4060

The Door buzzer sound circuit was two-tone sound. With the switch S1. working of circuit,The IC1 is a frequency dividing circuit, and generator a sound frequency came out.by the C1, R1 are the frequency generator. This audio signal from pin 7 and pin 4 into the pin 1 and pin 8 of the IC2a, IC2c respectively.
The IC2b of a frequency converter to control IC2c.When the control signal during the low (Low) 1.25 kHz frequency matches will IC2a.At the same time, the control signal is in a state IC2b high (High), frequency 300 Hz matches will IC2c. Output at pin 3 of low IC2a in the same condition,IC2a and IC2c output is sent to the IC2d.Which acts as both a signal and output to the transistors, Q1 acts as switches and amplifiers.The tones can be heard as two strokes.
The R3 acts as a volume, you add more value to make the sound softer, but smoother, a +6 volt power supply.

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Transistor quality checker with buzzer

You checked the transistor by measuring the resistance between the different pins. Sometimes it has problems, such as when measuring the resistance between the various legs correctly. But it does not work in the real circuit. Because while there is no measurement bias junction between CE. therefore, the detection transistor good or bad for sure. the transistors must be forward. and reverse bias at the same time. Injection of the electron, or hole between the junction. This circuit is a test. So, using the actual circuit. If the transistor test “good” circuit is the audio source it.
But if bad transistor. Integrated audio source will not come out. Or a very quiet voice. This circuit of operation of the simple astable transistors test to run during low flows about 20 mA,and transistors are tested to work with Q1 to generate frequency of about 2 KHz. the transistors Q2 expanding output to a buzzer. The switch S2 acts during the type test transistor NPN or PNP, the switch S1 using the press to test transistors.

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Put That Light Out

If you forget to switch off the light after leaving a seldom used room (such as the loft), there’s a strong likelihood that it could remain lit for months, running up an expensive power bill in the process. How can we prevent this waste? It’s not hard for electronics enthusiasts to design a little circuit to mitigate the effects of absentmindedness. The notion is simple; if the light is left on when the hatch or door is closed, a rhythmic sounder/buzzer signal produces an alarm that hopefully will not be masked by other noise.

The circuit is powered as long as the lamp bulb is switched on by light switch S1. If the reed switch S2 then signals that the hatch has been closed, the sounder operates. The red LED, mounted outside the loft next to the entry hatch, also indicates that the lamp up there needs to be switched off. The circuit does not use a transformer, meaning that the whole circuit is at mains potential. For this reason the components must be placed inside an insulated plastic case for protection, with no way that people can touch any part of the circuit (this includes the sounder).
The connecting wires to the LED and the reed switch contact must be fully protected to the same touch-proof degree too. For the sounder you can use any type that operates on direct current in the region between 1 V and 3 V. In this circuit the operating voltage is limited by the LED connected in parallel to the buzzer. Using a red LED will provide around 1.7 V to the sounder. The current requirement of this kind of miniature sounder is about 5 mA.

The connecting wires to the LED and the reed switch contact must be fully protected to the same touch-proof degree too. For the sounder you can use any type that operates on direct current in the region between 1 V and 3 V. In this circuit the operating voltage is limited by the LED connected in parallel to the buzzer. Using a red LED will provide around 1.7 V to the sounder. The current requirement of this kind of miniature sounder is about 5 mA.
Stefan Hoffmann
Elektor Electronics 2008
Read more : http://www.extremecircuits.net/2010/05/put-that-light-out.html