Transcript Breadboarding Suggestions

Troubleshooting Techniques
Troubleshooting Op-Amps
• Make sure power supply voltages are normal and it is good
idea to measure voltages (and signals) directly on the IC
Pins
• A simple test can be used to identify that an op-amp is at least
working. Figure below shown how the test is done. Simply short
the input temporarily to V+ and then to V-, the output voltage
should swing from near V- to near V+. If it fails, you can be fairly
certain the IC is bad.
• Verify the op-amp dc output offset voltage. If the op-amp uses a
dual supply, the offset voltage  few mill volts.
• Faults in the Noninverting Amplifier
• Faults in the Inverting Amplifier
1. Open Feedback Resistor (Rf)
1. Open Feedback Resistor(Rf)
If Rf open, the signal will still amplified by the
high open-loop gain.
If Rf open, op-amp operate at very high open-loop
gain.
Result: Output signal clipped
Result: Output signal clipped
2. Open Input Resistor(Ri)
2. Open Input Resistor(Ri)
If Ri open, no input signal to op-amp
If Ri open (i.e. infinite), the closed-loop gain become 1
Result: No output signal
Results: Output signal = Input signal
(Amplifier acts as voltage-follower)
Open
Rf
Ri
No Output
Signal
Vin