Op Amp

By

Virus

Safety

• Remove all jewelry and watches • Wear safety glasses• Unplug power plug when placing hands inside live

equipment.• Wear static wrist strap when troubleshooting

sensitive equipment such as computers. Honestly, I never do but for static electricity if you don’t then you could damage parts.

Feedback

• Rf means feedback resistor.

• The feedback resistor is your gain adjustment so if Ri = 1K and Rf = 10K then your Vout = 10 times Vin.

T1

T2

• T2 measures input signal enter “+” lead and T1 measures op amp output.

• Incoming signal “+” sign means noninverting signal in = noninverting signal out.

• Set Functiuon generator (XFG1) to 5kH

• Set Oscope until you see a nice clear signal

Phase shift

“In phase”

in sync (not the music group)

“Out phase”

Out of sync

T1

T1

Notice that T1 the waves are shifted since they’re traveling at different frequencies (time). They’re changing in time (1/f)

Notice that T1 the waves are in the same frequency of time traveling in harmony.

• Yellow is T1 signal• Red is T2 signal• What king type of op

amp signal is this?– Inverting

– noninverting

•In real life, when I troubleshoot I look just to make sure I get squiggles IN squiggles OUT. If squiggles goes in but NO squiggles out guess what? Op Amp is faulty or has no power.

Questions• What equipment must you remove before

begin troubleshooting?• What are the signals for two noninverting op

amps?• What does it mean “Out of Phase”?• What is the purpose of a feedback resistor?

Phase shift

• This is called 180 degree phase shift

• When T1 (Yellow) is positive at that same moment in time then T2 (Blue) is negative

• T1 = Yellow• T2 = Blue

Phase (degrees)

oscope

Answer next time…

More to come