Here is a simple Tachometer schematic. The basis of the frequency converter circuit-current, which converts the input signal into a proportional current measured pointer device. Deflection milliammeter proportion to the frequency input signal. To install the device on input pin A car should be connected to high voltage wire and pin B – to the… Read More »
The following diagram is a very easy and simple electronic combination lock based on IC LS7220. Component Part List: C1 = 1uF 25V C2 = 220uF 25V R1 = 2.2K Ohm Q1 = 2N3904 / 2N2222 D1 = 1N4148 / 1N4001-1N4007 K1 = 12V SPDT Relay / Any appropriate relay with 12V coil U1 =… Read More »
This easy electronic buzzer circuit built based on timer works for gaining the frequency. The IC timer NE 555 used as astable multivibrator operating at about 1kHz and produces a sound when switched on. The sound frequency can be adjusted by varying the 10K resistor. You may change the 10K resistor with variable resistor.
This is electronic bird chirp sound generator circuit which used to produce a sound like bird’s chirp. The transformer is a small audio transformer, type LT700. The primary is center tapped with an impedance of 1Kohms at 1KHz . The secondary has an impedance of 8 ohms. The circuit works with 9V power supply.
This is Electronic Siren circuit diagram which use standard discrete components. The sound produced imitates the rise and fall of an American police siren. When first switched on the 10u capacitors is discharged and both transistors are off. When the push button switch is pressed to 10u capacitor will charge via the 22k resistor. This… Read More »
The above diagram is a basic Uninterupted Power Supply (UPS) circuit. This basic UPS circuit is a very simple and inexpensive. This circuit can be adapted/modified for other regulated and unregulated voltages by using different regulators and batteries. For a 15 Volt regulated supply, you may apply two 12V batteries connected in series (it will… Read More »
This is the electronic circuit diagram of metronome sound generator. The circuit featured adjustable volume and beats/minute with potentiometers. LED used to be a beat indication. The circuit powered with 9V DC voltage, a 9V battery can be used to operate this metronome circuit. This circuit designed by Velleman.
Here the 35W power audio amplifier circuit based on LM391. Inductor L1 is constituted by 20 coils of wire, with thickness 0.9mm, round resistor R16. The transistors Q3-4 are the final amplification section, it should be placed on heatsink. If are used the Q3-4 in packing TIPxxxx they can be placed straight above in PCB.… Read More »
This is the electronic circuit diagram of aquarium temperature probe capable to monitor the temperature of water and indicate the rise in temperature through audio-visual indicators. This circuit uses diode 1N34 as the temperature sensing probe. The resistance of the diode will be vary depends on the temperature in its vicinity.