This electronic touch switch circuit is a touch switch ( on/off ) activated by skin resistance of finger. When the finger touch the on contact the a small current is delivered through skin to transistors to turn on the circuit .
The electronic touch switch circuit require few external components ( four transistors and four resistors ) and is very simple do build even for beginners .
A Wheel of Fortune electronic circuit can be designed using some logic ICs and other few components . This Wheel of Fortune circuit consist in a 10 LEDs that will light from 0 to 9 as the wheel pass each point . The rotation of the wheel start fast and gradually slows down to a random stop (with a click a t the each position of the wheel ) . After the wheel chases the selected led will lit few seconds and then goes out . To restart the wheel of fortune circuit the S1 push-button must be depressed . In time as the light of LEDs is spinning the circuit generate a click sound as the wheel passes each point .
This wheel electronic circuit needs to be powered by a 9 volts DC power supply .
This electronic door buzzer circuit schematic has a very simple function and is very easy to build. This door buzzer circuit use a LF351 operational amplifier and other few common electronic components . When the S1 push-button is depressed an initial positive voltage is placed on the C2 and the non-inverting terminal of the LF351 operational amplifier and the circuit will oscillate at a low frequency .
The used speaker for this project must have a impedance between 40 -80 ohms . The door buzzer electronic circuit need to be powered using a 9 volts DC power supply .