Tone-decoder
Adding a pair of monostable multivibrators to the output of a 567 tone decoder reduces its sensitivity to out-of-band signals and noise. In the absence of these multivibrators, the 567 is susceptible to unwanted output chatter. Alternative protection methods, such as feedback from outputs or the use of an input filter, are less effective than the monostable multivibrators. The output of the 567 is high when no tone is present and transitions to low upon tone detection. The tone decoder activates one monostable multivibrator through an AND gate. The period of the first multivibrator is configured to be slightly shorter than the duration of a tone burst. Furthermore, when the tone decoder's output drops, it triggers the second monostable multivibrator, which is set to a period slightly shorter than the interval between tone bursts. A flip-flop is employed to control the enabling and disabling of inputs to the monostable multivibrators, ensuring that spurious outputs from the tone decoder do not influence the final output.
The implementation of this circuit involves several key components: the 567 tone decoder, two monostable multivibrators (one-shot circuits), an AND gate, and a flip-flop. The 567 tone decoder is responsible for detecting a specific frequency tone and providing a high output when no tone is detected and a low output when the tone is present. This behavior is critical for the subsequent operation of the monostable multivibrators.
The first monostable multivibrator is triggered by the output of the tone decoder through the AND gate. The AND gate serves to ensure that the first multivibrator only activates when the tone decoder output is low, indicating that a tone has been detected. The timing configuration of this multivibrator is crucial; it must be set to a period that is shorter than the tone burst duration to effectively filter out any noise or spurious signals that may occur during the tone detection process.
When the output from the tone decoder transitions to low, indicating a tone detection, it subsequently triggers the second monostable multivibrator. The timing of this second multivibrator is similarly configured to be slightly shorter than the interval between tone bursts, allowing it to respond appropriately without being affected by noise or chatter.
The flip-flop plays an essential role in managing the state of the inputs to the monostable multivibrators. By enabling and disabling these inputs, the flip-flop ensures that transient signals or unwanted outputs from the tone decoder do not propagate through the circuit, thus stabilizing the overall output. This design effectively mitigates the risk of false triggering and enhances the reliability of the tone detection system.
Overall, this configuration significantly improves the performance of the 567 tone decoder in environments where noise and interference are present, ensuring that the output remains stable and accurate in response to valid tone signals.Adding a pair of one shots to the output of a 567 tone decoder renders it less sensitive to out-of-band signals and noise. Without the one shots, the 56Tis prone to spurious output chatter. Other protection schemes, such as feeding back outputs or using an input filter, do not work as well as the one shots.
The output of the 567 is high in the absence of a tone and becomes low when it detects a tone. The tone decoder triggers a one shot via an AND gate. The one shot"s period is set to slightly less than the duration of a tone burst. When the output of the tone decoder decreases, it triggers the second one shot. The second one shot"s period is set to slightly less than the interval between tone bursts. The flip-flop enables and disables the inputs to one shots so that spurious outputs from the tone decoder do not affect the output. 🔗 External reference
The implementation of this circuit involves several key components: the 567 tone decoder, two monostable multivibrators (one-shot circuits), an AND gate, and a flip-flop. The 567 tone decoder is responsible for detecting a specific frequency tone and providing a high output when no tone is detected and a low output when the tone is present. This behavior is critical for the subsequent operation of the monostable multivibrators.
The first monostable multivibrator is triggered by the output of the tone decoder through the AND gate. The AND gate serves to ensure that the first multivibrator only activates when the tone decoder output is low, indicating that a tone has been detected. The timing configuration of this multivibrator is crucial; it must be set to a period that is shorter than the tone burst duration to effectively filter out any noise or spurious signals that may occur during the tone detection process.
When the output from the tone decoder transitions to low, indicating a tone detection, it subsequently triggers the second monostable multivibrator. The timing of this second multivibrator is similarly configured to be slightly shorter than the interval between tone bursts, allowing it to respond appropriately without being affected by noise or chatter.
The flip-flop plays an essential role in managing the state of the inputs to the monostable multivibrators. By enabling and disabling these inputs, the flip-flop ensures that transient signals or unwanted outputs from the tone decoder do not propagate through the circuit, thus stabilizing the overall output. This design effectively mitigates the risk of false triggering and enhances the reliability of the tone detection system.
Overall, this configuration significantly improves the performance of the 567 tone decoder in environments where noise and interference are present, ensuring that the output remains stable and accurate in response to valid tone signals.Adding a pair of one shots to the output of a 567 tone decoder renders it less sensitive to out-of-band signals and noise. Without the one shots, the 56Tis prone to spurious output chatter. Other protection schemes, such as feeding back outputs or using an input filter, do not work as well as the one shots.
The output of the 567 is high in the absence of a tone and becomes low when it detects a tone. The tone decoder triggers a one shot via an AND gate. The one shot"s period is set to slightly less than the duration of a tone burst. When the output of the tone decoder decreases, it triggers the second one shot. The second one shot"s period is set to slightly less than the interval between tone bursts. The flip-flop enables and disables the inputs to one shots so that spurious outputs from the tone decoder do not affect the output. 🔗 External reference