The 340 circuit refers to the 340-second OTP (one-time programming input) playback circuit introduced by APULS, which can be divided into 256 voice segments. It can be controlled by hand or microprocessor. It can be used in voice explanation, voice teaching, voice guide, early childhood education, multi-point voice alarm system and other fields. This series has a total of 341\/170\/085 three models, corresponding to the three speed playback time.
340 circuit adopts 4-bit ADPCM compression algorithm to synthesize speech, PCM algorithm can also be selected (high sound quality, but short playback time), it has a variety of control modes, with M1 (17), Mo(18) two feet for four mode control selection.
The CH340 chip supports a 5V or 3.3V power supply voltage. When using a 5V operating voltage, the VCC pin of the CH340 chip inputs an external 5V power supply, and the V3 pin should be connected to an external power decoupling capacitor with a capacity of 4700pF or 0.01uF.
When the 3.3V operating voltage is used, the V3 pin of the CH340 chip should be connected to the VCC pin, and the external 3.3V power supply should be input, and the operating voltage of other circuits connected to the CH340 chip should not exceed 3.3V
What is the lm340 tube: lm340 is a regulated triode. It acts as a control voltage in the circuit.