Two Tone Electronic Siren Circuit

 

This is the circuit diagran of two tone electronic siren. The scheme is simple and easy to built, it based on two ICs with different task: produce audio signal and amplify the audio signal.

List of Components:

R1-R2-R3: 2.2KΩ
R4: 1KΩ
R5: 10K (potentiometer)
R6: 470Ω
C1 - C2: 10 uF
C3 - C4: 470 nF
C5: 10 uF
C6: 220 uF
IC1: Integrated Circuit TTL 7400
IC2: LM386
Z1: Zener 5 volts 1/2 watt
Speaker 8 Ω

PWM Controller Circuit using SN75603 and SN75604

Here the circuit diagram of PWM Controller which uses complementary half-H peripheral drivers SN75603 and SN75604, with totem-pole outputs rated at 40 V and 2.0 A. These drivers effectively place the motor in a full-bridge configuration, which has the ability to provide bidirectional control.

USB Cellphone Charger

This is the schematic diagram of cellphone charger circuit which connecter to the USB as main power. Whit this circuit, you can charger your cell phone from USB port in your PC or notebook.

The majority of the cellphones battery is appraised 3.6 volts at 1000 to 1300 mah. These battery packs have 3 Nimh or Lithium cells having 1.2 volt rating. Generally the battery pack requires 4.5 volts and 300-500 mA current for quick charging. Anyway, low present charging is better to build the proficiency of the battery. The circuit depicted here gives 4.7 directed voltage and sufficient present for the moderate charging of the cellphone.