I am trying to simulate n perform circuit of voltage to frequency converter using 555 and 741 in multisim 12, facing some problems in simulation..
1. when i applied input of 741 to ic555 i am not getting desired o/p
2. when i check o/p of 741 its square wave and when I applied it to 555 its came like image shows
i am totally stuck n dont knw where to start.
required suggestions, corrections, or i can perform this same task using any different circuit?
Find attachment for circuit diagram which i used n simulation results
at first the pot is connected wrongly. This way you can not adjust.
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The first OPAMP is an integrator. It regulates in a way, that IN- input has the same voltage than IN+ input.
--> therfore (as long as it is inregulation) IN- = 0V
--> therfore the discharge of the NE555 has no function.
With positive voltage of V3 (as FvM said) the output of the OPAMP will go to it´s negative limit.
Besides need to flip the input voltage, I wondered how the capacitor can be discharged.
I guess it can work with a bipolar LM555 (but not the 555 CMOS version) by utilizing the small positive output voltage of the saturated switch transistor, about 5 mV with 15V supply
Ohk Guys, thank you for suggestions,, sorry for positive input, but its still not as expected .. but what you can say now results can be achieve by some change in resistance n capacitance ?? or its cant still work ??..
New Results are find in attachment ...
thank you guys ..
I wondered how the capacitor can be discharged.
I guess it can work with a bipolar LM555 (but not the 555 CMOS version) by utilizing the small positive output voltage of the saturated switch transistor, about 5 mV with 15V supply
I don´t think it works, because connecting a "virtual GND" to a true "GND" will not cause any useful current to flow. And if, then it won´t directely discharge the capacitor, because the other connection of the capacitor has the high voltage referenced to GND.
--> My solution is a CMOS switch (with current limiting resistor. 100R?) across the C.
i have another circuit diagram .. guys what u can say about this ??
guys .. i know it is possible to implement through 741 n 555 .. bt how i have to find .. help me to short it out