Bipolar supply for a breadboard

When designing with op amps quite often a positive and negative supply are needed but all that is available is a low voltage positive supply.

The circuit below takes in a low voltage input of 5V-12V via a screw terminal and generates a positive supply via the MC34063A whilst at the same time generating a negative output via a discrete charge pump.

The circuit acts as a boost up to a positive voltage  set by the feedback resistors . The switch node is then switching the between the output voltage and ground so can be fed into a discrete diode charge pump to generate a negative voltage.

The circuit is designed on a single sided PCB below and is designed to fit

Single sided PCB for bipolar supply

into  whiteboard prototyping board as shown below

Bipolar power supply in breadboard

The bill of materials for this board is

QTY                     PART-REFS              VALUE
—                          ———                         —–
1                           R1                               12k
1                           R2                               1k
1                           R3                               100
2                           R4,R5                         1

1                           C1                               33u
1                           C2                               100u
1                           C3                               560p
1                           C4                              10uF
1                           C5                              1nF

Integrated Circuits
1                          U1                              MC34063A

1                          D1                             1N5401
2                          D2,D3                      1N4148

4                         J1,J2,J4,J5                 CONN-SIL2
1                         J3                                TBLOCK-I2
1                         L1                              100uH