A basic H bridge PWM circuit using an IC 555 integrated circuit can be used to control the barking of dogs and stop it.
The key component of this circuit is that the ultrasonic tweeter, is driven through the two IC 555s and four driver transistors.
Circuit Working:
Parts List:
| Category | Description | Quantity |
|---|---|---|
| Resistor | 1k | 1 |
| Potentiometer | 100k | 1 |
| Capacitor | Ceramic 1nF | 1 |
| Semiconductors | IC 555 | 2 |
| Transistors | BD679 | 2 |
| BD680 | 2 | |
| Other Components | Ultrasonic Tweeter | 1 |
As mentioned above, the two IC 555 referred to as IC1 and IC2, are crucial components of this circuit.
As an astable multivibrator IC1 generates the PWM signal.
PWM signal generated at pin 3 of IC1 is regulated by its frequency and duty cycle by the variable resistor pot, R1 and C1 timing components.
The configuration of IC2 is similar to a flip flop or set reset circuit.
The pins 2 and 6 of IC2 rise over 2/3 of VCC when pin 3 of IC1 is high, which in turn causes pin 3 of IC2 to drop.
The ultrasonic tweeter will now be pushed in a outward direction.
In the event that pin 3 of IC1 is low, pins 2 and 6 of IC2 will drop below 1/3 of VCC, which will raise pin 3 of IC2.
The ultrasonic tweeter will now be pulled in a inward direction.
When the potentiometer is modified, the resistance value vary, which eventually affects the output signals duty cycle as well as the time of the C1 charge and discharge.
The circuits load is a ultrasonic tweeter, whose push pull oscillation are controlled by the power transistors from T1 to T4 in H bridge arrangement.
The tweeter can oscillate in both push and pull manner, thanks to the H bridge which is activated by the ON/OFF PWM signal from IC1.
The IC1 555 generates a PWM signal, the duty cycle of which determines the ultrasonic tweeter operating frequency.
The potentiometer must be adjusted in order to change the duty cycle.
The entire circuit is powered by a 12V power supply.
Formulas
By utilizing the IC 555 to develop an astable multivibrator circuit, we may make a sound frequency that is unpleasant to dogs, which will encourage them to cease barking.
The formulas are provided below:
Formula for Frequency (f):
The settings of the resistor R and capacitor C define the oscillation frequency (f) in the astable mode of the IC 555.
f = 1.44 / (R1 + 2R2) *C
where,
- Resistors R1 and R2 are attached to the IC 555.
- C stands for timing capacitor.
To get the appropriate frequency for your application, change these variables as needed.
When employing ultrasonic frequencies, specifically make sure the sound produced is at a level that is safe for both humans and dogs.
How to Build:
To build a Dog Barking stopper circuit using this IC 555s, follow the below mentioned steps for connections:
- Gather all the components as shown in above diagram.
- Connect pin 1 of IC1 555 to ground
- Connect pin 2 to pin 6 of IC1 555.
- Connect pin 3 of IC1 555 to base of transistors T1 and T3.
- Connect pin 4 of IC1 555 to positive supply of 12V .
- Connect pin 6 of IC1 555 to pin 2 of IC1 555.
- Connect pin 7 of IC1 555 between resistor R1 and one leg of potentiometer.
- Connect pin 8 of IC1 555 to positive supply of 12V.
- Connect capacitor C1 from pin 2 and pin 6 of IC1 555 to ground.
- Connect P1 pot center leg to pin 2 and pin 6 of IC1 555.
- Connect pin 1 of IC2 555 to ground.
- Connect pin 2 and pin 6 of IC2 555 to pin 3 of IC 1 555
- Connect pin 3 of IC2 555 to base of transistors T2 and T4
- Connect pin 4 of IC2 555 to positive supply of 12V.
- Connect pin 6 to pin 2 of IC2 555.
- Connect pin 8 of IC2 555 to positive supply of IC2 555.
- Connect ultrasonic tweeter between the emitters of T1 ,T3 and T2, T4.
- Connect emitter of transistor T1 to emitter of transistor T3, connect collector of transistor T1 to positive supply and collector of T3 to ground, connect base of transistor T1 to the base of transistor T3.
- Connect emitter of transistor T2 to emitter or transistor T4, connect collector of transistor T2 to positive supply and collector of transistor T4 to ground, connect base of transistor T2 to base of transistor T4.
Conclusion:
The dog barking stopper circuit produces a high frequency square wave by using a 555 IC.
An H bridge circuit, which quickly changes the voltage polarity across a speaker is controlled by this signal.
Ultrasonic sound waves are produced by this quick switching, which are meant to annoy canines yet be undetectable to people.