i am designing an 8 channel Mosfet board which is used to on and off the driver ,but while testing i have connected a pwm board to the circuit, for controlling the driver but while testing there is a .8v -.7v on the pwm out even without giving a pwm signal, which will in turn actuate the driver, this problem is not faced when connecting to a 5v relay, what can i do to avoid the .8v disturbance

 

hi E21,
Please post a circuit diagram showing how the PWM is connected to the circuit in post #1.
E

 

Certainly we do not even see whatever point in the circuit the PWM signal is being measured.
IN ADDITION, the circuit itself makes no sense. An opto-isolator is being used to switch on and off a 24 volt supply to a three terminal voltage regulator that is feeding a "ground" connection. So the whole circuit, as shown, makes no sense at all.
IN ADDITION, I have never seen an application that requires a heat sink. The 4N35 opto-isolator is not a power device.

 

Your circuit is confusing:
Is U2 a LM7805 linear regulator or a MOS FET, as indicated by the terminals labelled "Gate", "Source" and "Drain"?
Where exactly in the circuit are you making your measurement?
What is model No. the PWM board that you are using for a source?
With the limited information you have given us, I would suspect that you need to add a resistive load between the output and ground of your PWM source, so that it has a proper ground reference.

 

Does the TS by any accident have a dual op-amp IC?? Those have a different pin-out.

 

Your circuit is confusing:
Is U2 a LM7805 linear regulator or a MOS FET, as indicated by the terminals labelled "Gate", "Source" and "Drain"?
Where exactly in the circuit are you making your measurement?
What is model No. the PWM board that you are using for a source?
With the limited information you have given us, I would suspect that you need to add a resistive load between the output and ground of your PWM source, so that it has a proper ground reference.

its p55nf06 mosfet

 

Your circuit is confusing:
Is U2 a LM7805 linear regulator or a MOS FET, as indicated by the terminals labelled "Gate", "Source" and "Drain"?
Where exactly in the circuit are you making your measurement?
What is model No. the PWM board that you are using for a source?
With the limited information you have given us, I would suspect that you need to add a resistive load between the output and ground of your PWM source, so that it has a proper ground reference.

its n channel mosfet
but negative switching causes this issue in the driver,giving some voltage to the pwm in driver

 

but negative switching causes this issue in the driver,giving some voltage to the pwm in driver

Try high side switching.

 

A "Proportional Control Valve" That utilizes an external 24 volt power supply and an analog control signal is likely to have internal circuits that require the power to be constant. So the whole concept of switching the valve "ON" and "OFF" by switching the power supply is not likely to perform adequately.
This means that the concept proposed, which does not work, is not able to be made to work.

We really need a description of the actual functioning required to be able to propose an arrangement that can provide that functioning.
What we are shown is a concept that can not possibly provide any useful function.

 

i'm with MisterBill2, what is the part number of the proportional valve that you are trying to control? the ones that i used are either using analog 0-10V or 4-20mA

 

There is no telling what sort of errors and damage opening the return connection could cause.