Headphone Amplifier circuit

This is a simple headphone amplifier. You can use any NPN transistor. You can drive this circuit with a 9V batery.

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HA2400 Programmable-attenuator

This circuit performs the function of dividing the input signal by a selected constant (1, 2, 4, 8, etc.). While T, Z, or L sections could be used in the input attenuator, this is not necessary since the amplifier loading is negligible

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LH003Wideband two-pole high-pass filter

The circuit provides a 10MHz cutoff frequency. Resistor R3 ensures that the input capacitance of the amplifier does not interact with the filter response at the frequency of interest.

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Digitally tuned low power active filter

This constant gain, constant Q, variable frequency filter provides simultaneous low-pass, bandpass, and high-pass outputs with the component values shown, the center frequency will be 235 Hz and 23.5 Hz for high and low logic inputs.

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TL081 Tunable notch filter

This narrow-stop-band filter can be tuned by the pot to place the notch at any frequency from 45 to 90 Hz. It attenuates power-line hum or other unwanted signals by at least 30 dB Because the circuit uses wide-tolerance parts, it is inexpensive

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SSM2044P Voltage Controlled Filter

At this circuit the SSM2044 IC is used, a 4 pole voltage controlled filter designed for electronic music applications. On-chip voltage control of resonance allows direct and easy interfacing with programmers and controllers. The IC features extended control range, low noise, and

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