Hi, I'm working on building a meter to essentially measure the conductivity between a set of probes. When I had the circuit setup on a breadboard it worked fine but when I tried switching the circuit onto the PCB I had designed I was unable to get the same results.

I'm attaching pictures of the schematic and board layout used.

- I am using and arduino UNO as the MCU. A0 and A1 on the schematic represent the analog inputs.
- the GND's on the schematic all run to the GND of the UNO
- P1 and P2 are the outer set of probes
- P3 and P4 are the inner set of probes
- the center UC2610 portion of the circuit is used for measuring current and the other UC2610 is used for measuring voltage

Any help would be greatly appreciated! Thanks!

 

What/how is it not working compared to before?
Not working at all?
Not the right output?

Have you checked each wire/trace on your PCB and protoboard to make sure they match?

 

Are you using and SMD cap for C3?
Are you sure PIN1 is connected to GND on the 555?

ED: It is ....

 

A suggestion for the future: identify pin 1 on all IC's on the PCB. People do it differently, but here's one way (actually, it's two ways.)

 

What/how is it not working compared to before?
Not working at all?
Not the right output?

Have you checked each wire/trace on your PCB and protoboard to make sure they match?

When it was setup on the breadboard it worked perfectly. but when I switched the parts over to the PCB P1 had no voltage supplied to it.

I've checked over all the traces yes.

 

Are you using and SMD cap for C3?
Are you sure PIN1 is connected to GND on the 555?

ED: It is ....

Yes C3 is a SMD.

And ya pin 1 on the 555 was connected to ground when i had it setup on the breadboard.

 

I am concerned about pin 5 on the 555 being connected directly to ground. What is the purpose of that? Are you sure that pin 5 shouldn't be connected through C3 to ground as opposed to being connected to pin 2?

 

I am concerned about pin 5 on the 555 being connected directly to ground. What is the purpose of that? Are you sure that pin 5 shouldn't be connected through C3 to ground as opposed to being connected to pin 2?

Oh I see what you mean. Ill try fixing that and see if that helps thanks!

 

Oh I see what you mean. Ill try fixing that and see if that helps thanks!

....and he never returned.......

 

....and he never returned.......

Yep...I guess we'll never know.

 

Which means either he has solved the problem or he has given up..
Just give him one more week.

Allen