As a signal goes through a rapid shift from base to higher value and after some period returns back to base value from higher value. It is considered a pulse signal. A Missing Pulse Detector Circuit is needed to identify such missed pulses when any of the pulses in this pulse chain do not occur that have the predefined interval duration. The detector circuit is capable of delivering notifications of missed pulses.
Hardware Components
The following components are required to make Pulse Detector Circuit
| S.no | Components | Value | Qty |
|---|---|---|---|
| 1. | Breadboard | – | 1 |
| 2. | IC | NE555 timer | 1 |
| 3. | Resistors | 10K ohms | 2 |
| 4. | Single strand wires | – | 1 |
| 5. | Ceramic Capacitor | 0.01uF,0.1uF | 1,1 |
| 6. | Battery | 12V | 1 |
| 7. | Function generator or square wave or triangular wave source | – | 1 |
| 8. | Oscilloscope | – | 1 |
| 9. | Push-button | – | 1 |
| 10. | Transistor | BC337 | 1 |
NE555 IC Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 555 Timer
Pulse Detector Circuit
Working Explanation
In-circuit R2 and C1 values decide the amount of time in monostable mode. Transistor BC337 is attached to the C1 capacitor. The input signal is connected directly to the IC 555 timer trigger pin and also connected to the transistor through a single 10k base resistor. The timer IC 555 sends a square wave over the display while the input signal does not have any missed pulse. Now a missing pulse comes, the T1 transistor is switched on, and when the C1 condenser attaches over the capacitor, the BC337 discharges it.
RC oscillator doesn’t have the optimal timing period for the IC 555 during this discharge phase. Consequently, the output remains high. Timing control of the circuitry is provided by the values of the resistor R2 and capacitor C1.
Applications and uses
• It is used with devices that monitor heartbeats
• To track errors in alternating current output.
• It can also be used for half-wave or full-wave identification in different operations related to signal source calculation.
