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FAB4312 – Non-Inverting Amplifier Module (Discrete OpAmp, PDIP OpAmp)

This is our FAB4312 Non-Inverting Amplifier Module.  You can use any single opamp, 8-pin PDIP package like an LME49710, NE5534 or equivalent. It also features Mill-max sockets if you want to mount a 2520-style discrete opamp, like our DOA-12, DOA-17, 990C, API 2520, or compatible discrete opamp.

A trimmer is also provided to let you adjust DC offset to zero volts (0V). A 2-pin header is provided for connection of your gain control potentiometer (or selector switch, or digital potentiometer, or switched resistor ladder network).  In the future, we’ll be providing FAB modules that will offer these different options for controlling the gain of your amplifier.

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FAB4312 – Non-Inverting Amplifier Module

The FAB4312 is a standard Non-Inverting Amplifier using OpAmps, accommodating both the PDIP8 IC format, and the API 2520-footprint Discrete OpAmp format.

If you’ll be installing a Discrete OpAmp, MillMax sockets are required to be installed on the board.  An external connection, RGAIN, is required to control the gain of this amplifier. One typically uses a 10K or 22K Reverse Log Potentiometer for RGAIN in this circuit configuration.

Feel free to change the values of RF, RGAIN and R3 to suit your purpose. The formula for Voltage Gain for the amplifier is conveniently printed on the FAB Module.

For CF, we’re using a 100pf C0G NPO ceramic capacitor. You may have to adjust this capacitor value to suit the OpAmp you’ll be using in case you encounter instability or oscillations.

In addition, a trimmer resistor (R2) is provided to let you adjust DC Offset Voltage as close as possible to 0 Volts. By adjusting the DC offset to as little as possible, you reduce clicking noise when changing gain settings. This may not be an issue if you’ll be using a potentiometer for RGAIN, but if you’ll be using a selector switch to vary the value of RGAIN, then you’d want your DC offset as small as possible.

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