Four Station Quiz
Here we have another Quiz circuit using a number of CMOS ICs. Now the number of contestants can be easily increased even though the present circuit shows only four. It uses a two input Quad AND gate (74HCT08), a four input Dual AND gate (74HCT21), a dual D flip flop (CD4013), and a 555. Truth [...]
Door Knob alarm
Here is circuit if you want an alarm to be sounded when somebody touches some thing. If any body touches say, the door handle, buzzer inside rings. But if want to keep the intruder away, keep the circuit on in the night or when you are away. It can be configured for use in a [...]
