Hi there,
I have an adjustable input voltage that swings from 0 to 30 volts DC. It can be at any value between these points.
I am trying to construct a simple inverter attenuator circuit using an op - amp.
I have had some success but its only by trial and error and its been suggested in the literature that your standard inverting amplifier working to attenuate instead can be unstable.
I would have also liked to run the op-amp from 30v-0 rather than +15/-15. My only success (in LT Spice came via the "unstable" option where I had rf being 30k ohms and rIn being 3k giving an amplification of 0.1.
I did try (from try a circuit this site https://www.eng.yale.edu/ee-labs/morse/compo/sloa058.pdf however its designed for AC and not DC.
How can I get a signal out of an opamp where if Vin=30 Vout=0 and when Vin=0 Vout =~3v.?
Is it possible to use an opamp in this regard using just a single rail?
Using a very slow sine wave (to approximate slow adjustment of the input signal) the wave form I am attempting is:
View attachment 61912
But it has to work as a DC attenuator - not AC. So I cannot use a cap and create virtual ground.
Kind regards
Simon
I have an adjustable input voltage that swings from 0 to 30 volts DC. It can be at any value between these points.
I am trying to construct a simple inverter attenuator circuit using an op - amp.
I have had some success but its only by trial and error and its been suggested in the literature that your standard inverting amplifier working to attenuate instead can be unstable.
I would have also liked to run the op-amp from 30v-0 rather than +15/-15. My only success (in LT Spice came via the "unstable" option where I had rf being 30k ohms and rIn being 3k giving an amplification of 0.1.
I did try (from try a circuit this site https://www.eng.yale.edu/ee-labs/morse/compo/sloa058.pdf however its designed for AC and not DC.
How can I get a signal out of an opamp where if Vin=30 Vout=0 and when Vin=0 Vout =~3v.?
Is it possible to use an opamp in this regard using just a single rail?
Using a very slow sine wave (to approximate slow adjustment of the input signal) the wave form I am attempting is:
View attachment 61912
But it has to work as a DC attenuator - not AC. So I cannot use a cap and create virtual ground.
Kind regards
Simon