Position: Index > Power Supply Circuit >

2_W_WITH_LOW_PASS_FILTER

2015-03-17 22:32  
Declaration:We aim to transmit more information by carrying articles . We will delete it soon, if we are involved in the problems of article content ,copyright or other problems.


2_W_WITH_LOW_PASS_FILTER
Developed for use in dual-conversion amateur receiver. Detected audio is passed through active low-pass filter-opamp arrangement U1-U2 and further amplified by 2-W audio amplifier U3. Simple voltage-divider circuit on pin 3 of U2 establishes artificial ground for U1 and U2. Low-pass rolloff starts at 2500 Hz, with about 20-dB attenuation of higher audio frequencies. IF heterodyne hiss is greatly attenuated and overall S/N ratio of receiver enhanced. Level-set 1-megohm pot between pins 2 and 7 of U2 establishes output gain for U1 and U2 together at about 0.8.-M. A. Chapman, High-Performance 20-Meter Receiver with Digital Frequency Readout, Ham Radio, Oct. 1977, p 48-61.