Here the circuit diagram of safer security system alarm. There are many security systems use a closed loop of wires and switches arranged so that whenever a door or window is opened, the loop will be broken and the alarm will sound. An obvious problem is that someone can tamper with the system, short out… Read More »
This is a low noise and distortion pre-amplifier and tone control circuit in one module. Using a special IC TDA1524A, this simple circuit is easy to build and will drive most of power amplifier. Schematic diagram:
Here is the circuit diagram of simple multitone alarm. This is a low cost circuit which is simple and easy to build. The main components of this circuit is based on dual op-amp MC1458 and LM 380. The two op amps inside the MC 1458 are used to produce square and triangular waves. LM 380… Read More »
Here is the circuit diagram of active DC voltage doubler which used to increase the DC voltage. This circuit drives relays of 24 and 18VDC from a 12V power supply. Use this circuit can be work with almost any PNP or NPN power transistor, of course the transistor with specific characteristic similar to the transistor… Read More »
Here is the circuit diagram of 100W audio amplifier which using power transistor BDW83D and BDW84D for the final amplification. It uses dual polarity power supply to work. Copyright belong to Smart Kit. The circuit should be seen like this: This is an exceptionally well designed amplifier, with a lot of power reserve, high fidelity,… Read More »
This is the circuit diagram of dancing LEDs which consists of 10 units LEDs. The 10 dancing LEDs circuit works like a audio level meter. The LEDs will be dance sequence with the sound level that entering the microphone. Components list: R1_____________10K 1/4W Resistor R2,R3__________47K 1/4W Resistors R4______________1K 1/4W Resistor R5,R6,R7______100K 1/4W Resistors R8____________820R 1/4W… Read More »
This a simple stereo electret microphone pre amplifier circuit. The below design diagram is the design for single channel, but the design of PCB layout is for stereo design og electret mic pre amp. For maximum performance, better quality, use solid capacitors or film capacitors and metal film resistors (1% tolerance). schematic diagram:
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 »
Here is the simple and low cost NiCd and NiMH battery charger circuit which can be used for various battery type and size. This battery charger use a regulator IC of LM317. Schematic diagram: The charge will start if a battery is connected between pins JP1-JP4 or JP2-JP4 or JP3-JP4. For example, if a battery… Read More »