Discrete Sliding Tone (Frequency Ramp) Doorbell


Posted on Feb 6, 2014

This doorbell circuit produces a low tone that will slide up to higher frequency. The equivalent total resistance connected between the base of Q1 and ground (Rbg), and coupling capacitor C1 determines the AF oscillator`s frequency. The resistance (Rbg) is equal to (R2 R1)R3. Here is the schematic diagram of the circuit: The R2 is used to set


Discrete Sliding Tone (Frequency Ramp) Doorbell
Click here to download the full size of the above Circuit.

the initial bias condition, adjusted to produce a pleasant low starting frequency doorbell tone. D1 will start to conduct when Capacitor C3 charge through R6 until it reaches D1 bias voltage level. Then the value of Rbg is paralleled by R4 and D1, and R5-D2-D3, and the values of diode`s equivalent resistance is gradually decreased as the C3 voltage ramp up. This decreasing resistance value make the output tone slides up in frequency. Two different diode path is provided to extend the linear area of diode conduction transition slope. With two path with different biases, after the single diode path has saturated, the second path provide further linear increase at higher voltage level.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

General-Purpose 5W Audio Amplifier With Ac Power Supply
10 led VU Meter using LM3915
Compact Switching Step-Down Converter By MAX639
ADUC845 12MIPS 8052 Flash MCU + 10-Ch 24-Bit ADC + 12-Bit DAC
Wideband UHF Amplifier - Antenna TV Amplifier Circuit
Metal detector 4
ACCURATE MOTOR SPEED CONTROL
Higher Input Or Output for L200 Voltage Regulator
Low Noise Design Schematics
THREE RANGE LIGHT METER
Discrete circuit elements constituting the ultrasonic transmitter
Fluorescent lamp electronic ballast circuit
A simple control circuit Lantern



Top