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Design Project: Audio Media-Based Signal Generator
4 questions By Tony R. Kuphaldt
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Question 4 of 4
It may be important to decouple the power supply rails in this amplifier circuit, just as it is important to decouple the power supply rails in a variety of circuits where fast [dv/dt] rates can exist, and/or when electrical noise is problematic. Explain what “decoupling” is, and what it does.
Reveal answerTo “decouple” the power supply means to place capacitors between the power supply rails to stabilize the DC voltage, shorting out AC noise and transient voltage spikes from interfering with the normal operation of the circuit.
Follow-up question: where do you think decoupling capacitors would be the most effective, located back at the power supply, or close to the power terminals of the operational amplifier and power transistors? Explain your reasoning.
Notes:I have seen the addition of decoupling capacitors turn a useless circuit into a flawless performer. In the case of an audio amplifier, DC power supply rails that are not properly decoupled may serve as feedback paths for unwanted signals, causing oscillations. These oscillations, if unchecked, may even damage the circuit!
