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NTE Integrated Circuit Low Voltage Audio Amplifier

Frys#: 1004373 Model: NTE823
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It is an audio power amplifier in an 8−Lead DIP type package designed for use in low voltage consumer applications.

Detailed Description
(Manufacturer # NTE823 )
Application Hints:
To make the this a more versatile amplifier, two pins (Pin1 and Pin8) are provided for gain control.With Pin1 and Pin8 open the 1.35kΩ resistor sets the gain at 20 (26dB). If a capacitor is put from Pin1 to Pin8, bypassing the 1.35kΩ resistor, the gain will go up to 200 (46dB). If a resistor is placed in series with the capacitor, the gain can be set to any value from 20 to 200. Gain control can also be done by capacitively coupling a resistor (or FET) from Pin1 to GND. Additional external components can be placed in parallel with the internal feedback resistors to tailor the gain and frequency response for individual applications. For example, we can compensate poor speaker bass response by frequency shaping the feedback path. This is done with a series RC from Pin1 to Pin5 (paralleling the internal 15kΩ resistor). For 6dB effective bass boost: R ≅ 15kΩ, the lowest value for good stable operation is R = 10kΩ if Pin8 is open. If Pin1 and Pin8 are bypassed then R as low as 2kΩ can be used. This restriction is because the amplifier is only compensated for closed− loop gains than 9V/V.
Input Biasing:
Pin2 and Pin3 of the NTE823 are biased to GND with a 50kΩ resistor. The base current of the input transistors is about 250nA, so the inputs are at about 12.5mV when left open. If the DC source resistance driving the NTE823 is higher than 250kΩ it will contribute very little additional offset (about 2.5mV at the input, 50mV at the output). If the DC source resistance is less than 10kΩ, then shorting the unused input to GND will keep the offset low (about 2.5mV at the input, 50mV at the output). For DC source resistances between these values we can eliminate excess offset by putting a resistor from the unused input to ground, equal in value to the DC source resistance. Of course all offset problems are eliminated if the input is capacitively coupled. When using the NTE823 with higher gains (bypassing the 1.35kΩ resistor between Pin1 and Pin8) it is necessary to bypass the unused input, preventing degradation of gain and possible instabilities. This is done with a 0.1µF capacitor or a short to GND depending on the DC source resistance on the driven input.
Brand NTE
Condition New
UPC 768249352815
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