Application circuit of HA11226

It is the application circuit of HA11226 . When recording, the recorded signal is sent from the input
coupling capacitor cl to the external amplifier VT. The signal output from VT
is filtered out by a low-pass filter composed of Li, k, c4, island, etc. and removes more than 15Ⅺ7 The high-frequency noise
is then sent to the internal amplifier A via the coupling capacitor Cb and pin 2 of the IC. Its output is sent to one input end of the adder
as the main channel signal , and the other is output via pin 5, through the recording and playback selection switch SAi, The 4 pins of SA2 and IC are added to the input end of the attenuation amplifier. After attenuation, it is sent to the high-frequency sideband amplifier B, and then divided into two outputs. One is limited and sent to the other input of the adder as a sub-channel signal. end. Since the two input signals sent to the adder are taken from the output of amplifier A, the adder adds the two signals, thus increasing the amplitude of the high-frequency component of the recorded signal and improving the efficiency of the signal sent to the recording head. When playing back, the signal to be played is introduced from the input terminal, sent to the external amplifier and internal amplifier A through the coupling capacitor cl, amplified, and then added to an input terminal of the adder. Since the record and playback switch SAi is placed in the playback position, the signal from the output end of the adder is directly taken out and sent to the variable attenuator, high-frequency sideband amplifier B, and limiting clamor, and is sent to the other input end of the adder as a sub-channel signal. Since the main and sub-channel signals added to the adder have opposite phases, the adder subtracts the two input signals, weakening the amplitude of the high-frequency components in the signal, thus restoring the original signal , achieving reduction of background noise and improvement of Signal-to-noise ratio function. Different from the CXA1100 series lc, the control voltage of the variable attenuation circuit of the HA11226 is amplified by the C amplifier and output by pin 6. After being rectified by the external rectifier VD] and VIwang and filtered by the filter capacitor, it is output by pin 3. Variable attenuator circuit for input circuit.     In order to ensure the performance of the circuit, all resistors and capacitors used need to be carefully inspected, and all components must meet accuracy requirements. Among them , Rio requires an error of <1%. The error of Rg and RI2 is <5%, and the other errors are <10%. Among the capacitors, C and C12 use tantalum electrolytic capacitors with an error of <1%, C4, C8, C13 use tantalum electrolytic capacitors with an error of <5%, and the rest are small polystyrene capacitors and electrolytic capacitors with an error of <10%. The external transistor is a low-noise transistor 2SC1354, and the required port value is between 30 and 40 . Two adjustable inductors, C4, and the island form a low-pass filter, and their inductance values ​​are 38rd-l and 23mH respectively. The input of this circuit is 30mV, and the output is 775mV.