POSITIVE TRIGGER As you can see, the 555 needs a negative trigger to turn on. If you need a positive trigger response, take a look at the positive trigger circuit. Resistor R1 serves as a pull-up ...

Note that all of the 555 devices that I tested worked OK, including the CMOS TLC555. To test this feature, I constructed a simple test circuit and took oscillographs of the signals. Pin 7 output ...

Fig 3. The pulse-generation circuit uses two 555 timing circuits to create a square wave with a duty cycle controlled by variable resistor R28.

A 555 set up in astable mode running at 31.25 Hz provides the clock, synchronized with the signal by connecting the comparator’s output to the 555 trigger input.

Here’s your useful and beautiful circuit for the day — [New Pew]’s vibration sensor takes manual control of the flip-flop inside a 555 timer and lights an LED in response. Use it … ...

A close look at the circuit reveals that it consists of a discrete D-type flip-flop formed by NAND gates U1a-U1c. The setup delay of the LS series gates is around 10 ns. This causes the settling ...