Electronics > Beginners

Can I use a Lab Bench PSU and a Function Generator at the same time?

<< < (3/7) > >>

codingwithethanol:
xavier60,

I apologize, that was a bit longer than 20 minutes (alot longer)
The max my unit can do is 18V so im gonna keep it at 16V p-p so 8VAC

Here is the breadboarded circuit:
http://prntscr.com/nt39g1

I've set my function generator to ~1kHz, 3V p-p (1.5VAC), I am viewing the output on my oscilloscope without turning on the PSU and it looks rather unusual (top is function generator output, bottom is opamp output):
http://prntscr.com/nt39kt

[edit] Just so you know, I discovered that my opamps were actually produced by ST, and checked their datasheet
http://prntscr.com/nt3anq

Anyways, ready to flip the switch, hope nothing dies

codingwithethanol:
Ok this is very unexpected:


I have no clue what could be causing this
An even bigger insult is that it doesnt even produce any gain

xavier60:
You need to follow my diagram exactly. Both PSU channels are used, they are PS1 and PS2 in the diagram, wired in series just like two batteries might be wired in series. Use the red and black terminals, not the green ones.
Set each channel to 5V for now.
The op-amp wont do anything meaningful until powered up correctly.
I'll add more detail if I spot specific problems. 

Start with a much lower signal input level like 100mV p-p.
Correction: I see that they are white/black terminals for +/- on the PSU.
Extra: The op-amp will appear to function oddly if the Pot is at a particular one of its extreme settings. 
Leave it set near the middle until things stat to make sense.

codingwithethanol:
Here is how i have the circuit wired to the PSU:
http://prntscr.com/nt3mjg

Ive seen people run both channels in series, I can probably do so if needed

I followed the schematic when breadboarding
Heres an annotated picture:
http://prntscr.com/nt3qdr

As I was annotating, I realized I had switched the inputs by accident, and switched them back
The output is relatively the same as before:
[edit] forgot to paste image link
http://prntscr.com/nt3rzu

Anyways, the minimum my function generator puts out is 2V p-p (1VAC), so ill make a voltage divider to get it lower
[edit] I just sweep the pot to test, the only thing that changes is the amplitude

xavier60:

--- Quote from: codingwithethanol on May 25, 2019, 06:14:48 am ---Here is how i have the circuit wired to the PSU:
http://prntscr.com/nt3mjg


--- End quote ---
Although that's not the  correct way, it can be made to work, Connect a resistor from the + terminal to the green terminal. Connect another resistor of the same value from the - terminal to the green terminal. 1KΩ should do.
The idea is to balance the + and - rails. Measure the voltage of each rail with respect to ground, they should be about the same as each other.

More: Take the rail measurements at the pins of the op-amp. Also both input pins and output should be 0V.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod