Clamp circuit help

Bitrex · 2011-09-10T22:53:52+00:00

I'm working on a little battery-powered project where I need to amplifya low frequency signal by about 1000, and clamp the output of theamplifier circuit to remain above about 1 volt at all times. Also, withno signal the output of this section of the circuit should remain atapproximately the clamp voltage. The circuit I came up with uses an NPNtransistor in the feedback loop for the clamp - I've included theLTSpice netlist.The circuit seems to work OK - except for the fact that when the clampcircuit engages the simulation shows a big burst of oscillation at theoutput. I haven't breadboarded the circuit yet to see if it happens"IRL", and I'll most likely be using a different single supply op amp.Anyone have any suggestions on how I might address this, if it shows upin the real circuit as well? Thanks.Version 4SHEET 1 1140 680WIRE 64 -208 64 -240WIRE 224 -160 176 -160WIRE 272 -160 224 -160WIRE 352 -96 336 -96WIRE 464 -96 432 -96WIRE 64 -80 64 -128WIRE 176 -80 176 -96WIRE 528 -32 400 -32WIRE 400 0 400 -32WIRE 400 0 288 0WIRE -32 16 -96 16WIRE 96 16 48 16WIRE 288 48 288 0WIRE 336 64 336 -96WIRE 352 64 336 64WIRE 464 64 464 -96WIRE 464 64 448 64WIRE -96 144 -96 16WIRE -16 144 -96 144WIRE 96 160 96 16WIRE 96 160 48 160WIRE 112 160 96 160WIRE 336 160 336 64WIRE 336 160 256 160WIRE 352 160 336 160WIRE -176 176 -256 176WIRE -32 176 -112 176WIRE -16 176 -32 176WIRE 464 176 464 64WIRE 464 176 416 176WIRE 288 192 288 112WIRE 288 192 240 192WIRE 352 192 288 192WIRE -96 240 -96 144WIRE -32 240 -32 176WIRE 240 288 240 192WIRE -256 336 -256 256WIRE -96 336 -96 320WIRE -32 336 -32 320WIRE 16 336 16 192WIRE 288 336 288 272WIRE 384 336 384 208FLAG 64 -80 0FLAG 64 -240 VccFLAG 384 336 0FLAG 384 144 VccFLAG 224 -240 VccFLAG 272 -160 Vref1FLAG 224 -80 0FLAG 288 336 0FLAG 240 288 Vref2FLAG -96 336 0FLAG -32 336 0FLAG 16 128 VccFLAG -256 336 0FLAG 16 336 0FLAG 176 -80 0FLAG 528 -32 Vref1SYMBOL Opamps\LT1014 16 96 R0WINDOW 3 14 116 Left 0SYMATTR InstName U1SYMBOL Opamps\LT1014 384 112...

Sep 10, 2011 62 Replies

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John Larkin 14 years ago

Cuts? What cuts?

Death by whining? I don't think so.

John

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John Fields 14 years ago

:-)

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John Fields 14 years ago

http://www.youtube.com/watch?v=Eb6aH9Sg2Ns

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