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Why does my OP-amp change value so incredibly slow?

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Addez

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Here is my circuit, it amplified a boolean (from 0-1 volt) to 0-4ish volts.
show6.png

The issue is that when it's going back to 0 volts, it takes sinks super slowly. Same speed as the capacitor take to unload.

show7.png


It has to do with the capacitor and the JFET but I have no clue what it is or what to do about it.
Any suggestions?
 

Hi,

I wonder why it does anything.

--> both supply pins are connected to +5V. So it has no negative supply.

Klaus
 

both supply pins are connected to +5V. So it has no negative supply.
Click to expand...
V8 is negative, but the sign is perfectly hidden. Addez would want to arrange the circuit elements more clearly.

The circuit is behaving expectable. The negative output ramp is cause by forward biased PJFET gate junction forcing the OP into current limit, by nature of the circuit. You could add a series resistor, e.g. 100 kohm to limit the gate current in forward bias.
 

In addition to correcting the wrong opamp power supply as pointed out by the others, unless you have a specific reason for wanting to use a JFET, use an N-channel MOSFET and you'll see a very different result.
 

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