Panel switch wiring

This Simple Positive And Negative Voltage Power Supply Circuit Diagram provides a precision voltage source that can be adjusted through zero to positive and negative voltages, which eliminates reversing connections on the power supply. Also, it is possible to get exactly 0 V, without some offset. As to how this schema works, first consider the -1 V/V to +1 V/V linear gain-control amp (see the figure). A Burr-Brown INA105 difference amp is used in a unity-gain inverting amp configuration. 

 Positive And Negative Voltage Power Supply Circuit Diagram

A potentiometer is connected between the input and ground. The pot`s slider is connected to the noninverting input of the unity-gain amp; this input is typically connected to ground. With the slider at the bottom of the pot, the schema is a normal-precision unity-gain inverting amp with a gain of -1.0 V/V ± 0.01% maximum. 

With the slider at the top of the pot, the schema is a normal-precision voltage follower with a gain of ± 1.0 V/V ± 0.001% maximum. With the slider in the center, there`s equal positive and negative gain for a net gain of 0 V/V. The accuracy between the top and the bottom will usually be limited by the accuracy of the pot.

Source Simple Positive And Negative Voltage Power Supply Circuit Diagram

In this Auxiliary Negative Dc Supply Circuit Diagram, IC1 (CD4009) is used as a square-wave oscillator at approximately 25 kHz. CI and Rl set this frequency. C2, Dl, D2, and C3 form a p-p rectifier, which outputs about -3.5 Vdc. This schema should be useful where a small negative dc supply is required, but only positive dc voltages are available.