Random circuits

Here are some of over 800 projects from our free circuit diagrams database. For more, try browsing categories menu on the left.

Laptop Protector

Protect your valuable laptop against theft using this miniature alarm generator. Fixed in-side the laptop case, it will sound a loud alarm when someone tries to take the laptop. This highly sensitive circuit uses a homemade tilt switch to activate the alarm through tilting of the laptop case. The circuit uses readily available components and can be assembled on a small piece of Vero board or a general-purpose PCB.... [read more]

Hot Water Level Indicator

A simple device to indicate various levels of hot water in a tank.... [read more]

Jogging Timer Circuit Diagram

This circuit was developed since a number of visitors of this website requested a timer capable of emitting a beep after one, two, three minutes and so on, for jogging purposes. As shown in the circuit diagram, SW1 is a 1 pole 9 ways Rotary Switch. Setting the switch in position 1, the Piezo sounder emits three short beeps every minute. In position 2 the same thing happens after a 2 minutes delay, and so on, reaching a maximum interval of 9 minutes in position 9.... [read more]

Two-wire Lamp Flasher

This circuit has been designed to provide that continuous light lamps already wired into a circuit, become flashing. Simply insert the circuit between existing lamp and negative supply. Especially suited for car or panel pilot lights, this device can drive lamps up to 10W.... [read more]

Salt Taster

This circuit was designed to detect the approximate percentage of salt contained in a liquid. After careful setting it can be useful to persons needing a quick, rough indication of the salt content in liquid foods for diet purposes etc.... [read more]

Tan Timer

This timer was deliberately designed for people wanting to get tanned but at the same time wishing to avoid an excessive exposure to sunlight.... [read more]