Powering Up The Op-Amp

Powering up the Op-Amp 

Pin 1:

If you have not already done so, wire the bus strips on your breadboard to provide positive power, negative power and ground buses. Whatever color scheme you have chosen for your wires, you should use the green binding post for ground, the black for -15 V, and the red for +15 V.

Pin 2:

Connect a 0.1 mF capacitor between the +15 V power bus and ground. Connect another 0.1 mF capacitor between the -15 V power bus and ground. The power buses for your board should look like this: These capacitors are the first of several bits of "magic" we will employ to try to avoid amomolous behavior. As we will see when we study control systems, feedback also has a dark side. In particular, feedback which becomes positive at some frequency can cause instabilities. Although we have not deliberately introduced any positive feedback, feedback can occur where we don´t intend it. The purpose of these capacitors is to prevent it from occurring via the power supply, which at high frequencies is not a very ideal voltage source.

Pin 3:

Plug an op-amp into the breadboard so that it straddles the gap between the top and bottom sections of the socket strip. If you have wired the power buses as suggested above, Pin 1 should be to the left.

Pin 4:

Connect Pin 4 (VCC- ) to the negative power supply bus (-15 V). Connect Pin 7 (VCC+) to the positive power supply bus (+15 V).

Pin 5: 

Set the METER SELECTOR on the power supply to +20V. With the power supply disconnected from the breadboard, turn on the supply and adjust the left-hand voltage control until the meter reads 15 volts.

Pin 6:

Turn off the supply and connect the supply to the breadboard with banana plug patch cables. Connect the 0 to -20V terminal (black) to the black binding post on your breadboard, the 0 to +20V terminal (red) to the red breadboard binding post, and the COMMON terminal (light blue) to the green breadboard binding post. Note that none of the power supply output terminals are connected to ground. If we want the power supply zero volt reference connected to ground, we must make the connection ourselves.

Keywords : Power, symetrical, Simetrical, Supply, Powering, Op-Amp, 741, LM741
Writer : delon  |
17 Dec 2005 Sat   
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