1. Amplitude adjustment and measurement: After confirming that the wiring of the oscillating circuit is correct and all components are properly selected, turn on the DC power supply. If oscillation occurs, use an oscilloscope to observe the output voltage waveform. If the positive feedback circuit is disconnected and the waveform disappears, it indicates that the displayed waveform is not interference or parasitic oscillation. If no waveform appears on the oscilloscope, the circuit isn’t starting. In this case, check if the positive feedback is connected correctly, whether the feedback polarity is accurate, and if the gain-bandwidth product of the op-amp meets the requirements. Then proceed with the following adjustments: (1) Increase the positive feedback coefficient to enhance the positive feedback. (2) Reduce negative feedback to increase the amplification factor. (3) For a transistor-based oscillator, increase the quiescent operating point, raise the collector load resistance, or improve the quality factor of the oscillating circuit to boost the amplitude. These methods can also help adjust the output voltage level accordingly. 2. Adjustment and measurement of the oscillating waveform: The output should be a clean sine wave. If the waveform is distorted, reduce the positive feedback and increase the negative feedback to lower the loop gain. Then check the transistor’s quiescent operating point, the quality factor of the LC tank circuit, and the slew rate of the op-amp. If high-frequency noise or spurious signals appear on the waveform, it may indicate parasitic high-frequency oscillation. To resolve this, rewire the circuit, shorten long feedback paths, add small resistors for damping, or improve decoupling circuits to suppress unwanted oscillations. 3. Frequency adjustment and measurement: Use an oscilloscope for basic frequency observation, and a digital frequency meter for precise measurements. Adjust the frequency by modifying the parameters of the frequency-selective network in the oscillator. For RC oscillators, adjust resistor or capacitor values. For LC oscillators, change the variable capacitor, coil core position, or number of turns. Be cautious about the influence of component parasitic capacitance and the input impedance of testing equipment during adjustments. 4. Measurement of amplitude and frequency stability: (1) For short-term stability, vary the DC power supply voltage by ±10% and change the load impedance. Measure the output voltage and frequency changes to calculate ΔU0/U0 and Δf0/f0. (2) Long-term stability can be evaluated by monitoring the relative changes in amplitude and frequency over one hour (or half an hour). This helps ensure the oscillator remains stable under different conditions.
IC SOCKET & Machined SOCKET
IC SOCKET & Machined SOCKET
HuiZhou Antenk Electronics Co., LTD , https://www.atkconn.com