Ive been trying to recreate this circuit on LTSpice but it just doesnt seem to be working. I built it up until IC2 and instead of using the virtual ground set up, I used normal PSU rails for all the Opamps.

 

You might have Vcc and Vee backwards. I can't see your entire schematic.
Post your files.
Pick real diodes. In4148 or something. 1n914

 

yeah i just changed diodes to real ones, yet no change in output. heres the circuit file

 

first thing you ties the - of V1 and V2 together. Still I would prefer to have the full list of values in the book.

 

What do you want the circuit to do?

 

That "IRG" under IC2 is not implemented. Probably an old book and used 741 and the pot is connected to the offsets pins

 

REmove the unused RC circuits above U3. They do nothing at all. And, in the first image, U1 was probably an LM324.

 

REmove the unused RC circuits above U3. They do nothing at all. And, in the first image, U1 was probably an LM324.

it is a rotary switch but LTspice does not even have potentiometer (native) and you have to add it

 

yeah i just changed diodes to real ones, yet no change in output. heres the circuit file

Hi,

It seems to work for me.

Just a small note...
We normally use Vcc for the positive supply, and Vee for the negative supply. Swapping the two may confuse some readers.

 

What do you want the circuit to do?
View attachment 364874

I need a fully rectified square wave at the 1Meg resistor. it seems like i got something similar but i dont understand why the amplitudes half the input square wave. Also im not sure how the rotary switch affects the final output value, because I tested it while connecting to the different modes and still got the same output. It is a circuit that measures the capacitance of an unknown capacitor while the output is connected to a multimeter. The multimeter measures the capacitance in volts.

 

Hi,

It seems to work for me.

Just a small note...
We normally use Vcc for the positive supply, and Vee for the negative supply. Swapping the two may confuse some readers.

Hey there, so the amplitude of the output should be half the input? Also apologies for the incorrect labelling, im new to electronics and LTSpice so im getting used to it slowly, thank you for correction.

 

I fully completed the circuit and made changes so that it matches the schematic. However, it seems like the "completed" circuit is not behaving as it should be, and now im unsure what output is expected at the "Output" resistor. I attached the new file of the circuit below, any help is appreciated. Many thanks.

 

hi Lee,
You have Gnd Node on -Vee
E

 

hi Lee,
You have Gnd Node on -Vee
E
View attachment 364900

where do i place the ground?

 

hi LEE,
This line is also missing.
E

 

hi Lee,
IC1d output is the Virtual Ground.
E

IC!d job is to divide the 9v battery into two voltages, +4.5v and -4.5V with its out put at a virtual Zero volts

 

hi Lee,
This looks incorrect, what is IC2 OPA type??
E

 

hi Lee,
This looks incorrect, what is IC2 OPA type??
E
View attachment 364904

hey eric, all op amps are universalopamp

 

hi Lee,
This what I have so far with a 'fudge' mod on IC2.
Note the BAT diodes D1 ,D2.
E
BTW my pot symbols are different from yours.

 

hi Lee,
IC1d output is the Virtual Ground.
E

IC!d job is to divide the 9v battery into two voltages, +4.5v and -4.5V with its out put at a virtual Zero volts

oh that makes sense, but ltspice is not letting me simulate it without a ground, i also added the missing line you mentioned, yet no change. Apologies, I am begineer at this since im a first year student.