Dead Band Circuit

[321Mark]

First of all, thanks for the help on the AGC circuit post. The problems I was having were in the RF path, not the AGC path. Circuit works fine except...

I need a dead band circuit. I want to ignore the output of the detector until it gets to about 0.5 volts, then bring the ACG into play. What first comes to mind is a comparator, but I'm worred about the abrupt transition.

I found a circuit in "Intuitive IC OP-Amps" by Frederiksen. The circuit is shown on page 207. Fig. 5-53. The circuit shown is a Bounding circuit. I breadbaorded it and it works well - cool circuit.

The text states that if you remove one resistor (R*), it will function as a deadband circuit.

No luck, works fine as the boundind circuit, but doesn't work as advertised as a deadband circuit.

Anyone have a simple deadband circuit suggestion?

Thanks,

Mark

 

[nbucska]

yes-- a transistor.Untill about Vbe <.65V no current.

Plesae read FAQ240-1032
My WEB: <

http://geocities.com/nbucska/>

 

[Warpspeed]

Or back to back diodes in series with the feedback path.

 

[itsmoked]

Both suggestions are good!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com