Figure 3.18. The lower prong of a two wire line plug goes to the bottom end of a transformer primary. The upper prong goes through a fuse labeled 0.5 eh, then through a switch to the upper end of the primary. There is a lamp in parallel with the primary. The transformer secondary has its center-tap connected to circuit ground. The upper end of the secondary goes to the anode of a diode. The lower end of the secondary goes to the anode of another diode. The two cathodes are connected together and go to the positive end of a 4700 microfarad capacitor. The other end of the cap goes to ground. The positive end of the cap goes to the input terminal of a 5 volt regulator labeled LM309K. There is a 0.1 microfarad cap connected between the input terminal and the common terminal of the regulator. The common terminal of the regulator goes to ground. There is another 0.1 microfarad cap connected between the output terminal and common terminal of the regulator. The output terminal of the regulator goes to the positive end of a 100 microfarad cap. The negative end goes to ground. The output of the regulator goes to the plus 5 output terminal of the power supply. The negative output of the power supply goes to ground. The positive end of the 4700 microfarad capacitor goes to the I terminal of an LM317 positive adjustable regulator. There is a 0.1 mike cap going from the I terminal to ground. There is a 10 mike cap connected between the A terminal of the regulator and ground. There is an 82 ohm resistor connected between the O and A terminals. There is a 1 k ohm pot connected as a rheostat from the A terminal to ground. There is a 20 mike cap connected from the O terminal to ground. The o terminal goes to the cathode of a diode. The anode is grounded. The O terminal goes to the positive 1.2 to 15 volt output. Now going back to the transformer secondary, the top end goes to the cathode of a diode and the bottom end goes to the cathode of another diode. The two anodes are tied together and go to the negative end of a 2200 mike cap, the positive end is grounded. The negative end of the 2200 goes to the I terminal of a negative adjustable regulator, LM337. There is a 0.1 mike cap from the I terminal to ground. There is a 10 mike cap from the A terminal to ground. There is an 82 ohm resistor from the O terminal to the A terminal of the regulator. There is a 1 k ohm pot connected as a rheostat and connected from the A terminal to ground. There is a 20 mike cap from the O terminal to ground. The O terminal goes to the anode of a diode. The cathode is grounded. The O terminal goes to the minus 1.2 to minus 15 volt output. A single ground connection serves as the return for all three supplies. End verbal description.
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