This is the circuit diagram of two tones train horn which built based dual timer IC NE556. The circuit is quite simple and easy to built and of course inexpensive. The circuit diagram is in a “basic” design, you may try to modify this circuit, for example: use a low power audio amplifier and use… Read More »
This is the circuit diagram of TRIAC, SCR and Transistor tester. This is a very simple circuit which can be used for testing of SCRs as well as triacs. The circuit could even be used for checking of PNP and NPN transistors. The circuit works on 3V DC, derived using a zener diode in conjunction… Read More »
Here is the USB printer switch circuit design with two USB input ports and one USB output port. This a really simple device that allow two computers (desktop/laptop) to select a single USB printer or some other USB device, such as an external flash drive, memory card reader or scanner. A rotary switch selects the… Read More »
This is a really simple smoke alarm circuit design. The circuit consists of two important modules that are sensor module using a photo interrupter module and alarm module using a tone generator IC NE555 with astable multivibrator configuration and then connected to the speaker, so you can hear the alarm sound.
This is the digital fan speed control circuit design that can be utilize to control the speed of 220V fans using induction motor. The speed control is nonlinear, i.e. in steps. The current step number is displayed on a 7-segment display. Speed can be varied over a wide range because the circuit can alter the… Read More »