how to find a fault on the circuit

[karan1986]

having a problem to get an output on this ciruit......The input parameters are of 5v peak to peak and the frequency is 1 Mhz......Can some one pls rectify the fault in this cct and give an explanation where I was wrong as I am new to this software and dont have any idea

[Tien_P]

Hi Karan,

The function generator is connected to a capacitor then to a DC source (V2) so that node will always be high, your circuit was not correctly wired. To troubleshoot any circuit, start at the input and use the instruments to the nodes voltage making the get the right output, do this until you reach the output, this generally how you find problems.

[karan1986]

mr Tien

I tried the option, and I removed the capacitor,so as to check if I can get an output,

a) the capacitor only blocks DC so should not have any problem with the AC circuitry

b)When I removed the capacitor now the oscillator an output signal but with no frequency or voltage......there is just a single line tha is displayed

c) Im still stuck with it, can u pls help me out?

[Tien_P]

Hi,

The function generator has two pins, the top pin is the Sync and the bottom is the Output. You connected the output signal to ground and used the Sync pin as the input signal that means you will get a pulse between 0V and 5V. You usually don't use this pin.

It's not the capacitor that I concern about, it that you connect the input signal to a 5V DC source and that's why you are reading a flat line. I don't what this circuit is for and the logic of it seems strange to me, what are you trying to do with this circuit?

[karan1986]

Mr Tien,

First of all thanks for this valuable input, the circuit is to drive a LASER diode in order for free space optical communication,its one that is used for driving LAN for free space optical communication. The 

Secondly can you please tell me how to use the hidden pins in the hex inverters I have to ground the U1E,U2E,U3E and give VCC to U1 A,U2A and U3A

i am not getting an output at the end of the hex inverters. Any input will be of a valuable help

Thanks

Karan

[Tien_P]

Hi Karan,

To connect power and ground to the hidden power pins, you just need to place a VCC or DGND symbol on the workspace and the hidden pins will make the connection. You can refer to this knowledge base for more details.

http://digital.ni.com/public.nsf/allkb/2E2C6574E8DC12F48625719D004D00E7

[MinPyaeSone33]

Hi I am electrical student. I analyzing  12V 10A switching power supply circuit in multisim and simulation error occur evertime how to fix? Point me please that circuit where is wrong. please help me.