How to Use Positive Regulators for Negative Outputs
- 1). Solder the bare wire ends of the line cord to the transformer’s primary solder lugs. Wrap each connection with a few inches of electrical tape. Solder one end of a 12-inch piece of 22-gauge wire to each of the transformer’s secondary solder lugs. Each secondary solder lug should have one wire soldered to it. Connect the free ends of the wires in another step.
- 2). Insert the leads of the 2-amp bridge rectifier into the solderless breadboard. Make sure each lead goes into a separate column in the breadboard. The holes in the breadboard are electrically connected in columns, but the columns are insulated from each other. To make a connection in the breadboard, insert wires or leads so they share a column.
- 3). Insert the free end of one of the 12-inch transformer wires so it connects to a rectifier lead marked with the AC symbol, “~.” Insert the free end of the other 12-inch wire so it connects to the remaining rectifier AC input.
- 4). Set the negative lead of the 470-microfarad capacitor into the breadboard so it connects to the rectifier’s positive lead. Set the positive capacitor lead so it connects to the rectifier’s negative lead. Insert the LM7812’s input lead so it connects to the rectifier’s negative lead.
- 5). Insert the LM7812 regulator’s common lead so it connects to the 470-microfarad capacitor’s positive lead. Insert the .1-microfarad capacitor so one lead connects to the regulator’s output lead and the other connects to the regulator’s common lead.
- 6). Connect one end of a 12-inch wire to the regulator’s output lead. This wire serves as the regulator circuit’s common connection. Connect one end of the remaining 12-inch wire to the regulator’s common lead. This wire is the regulator circuit’s negative voltage output.
- 7). Double-check your connections. Turn the digital multimeter on and set its selector knob to DC volts. Touch the multimeter’s positive probe to the free end of the regulator circuit’s negative output wire. Touch the multimeter’s negative probe to the free end of the regulator’s common wire. Plug the line cord into a 110-volt socket. The multimeter should display a reading of -12 volts.
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