I have a square wave circuit based on a 555, (2) CD4017, a CD4013 which in turn feeds the square wave to the UAF42. Is it a requirement that the V+ and V- for the UAF42 be separate from the other IC's (555, CD4017 & CD4013) supply voltage? Will the UAF42 only function if connected in this way? The only way I have been able to produce a sine wave from the UAF42 is if the supply voltages are separate from the other IC's in the ckt.
Regards,
Greg
Greg,
It should not be necessary to use separate power supplies. I believe that you are probably not connecting the supplies correctly. Can you please provide a schematic showing your full circuit? Be sure to clearly indicate how the supply connections are interconnected.
Regards, Bruce.
Bruce,
I have verified all of my connections are correct according to the datasheet. I have attached the schematic of my circuit. I'm using a bench-top power supply for the +/-12VDC and the gnd.
I don't see any reason why using the same power supply should cause a problem. A power supply providing +12V, ground and -12V with the +12V and ground shared with the UAF42 should work well. I believe that you are probably overlooking some simple interconnection problem.
To troubleshoot, I suggest the following: Measure with the ground of an o-scope connected to pin 11 of the UAF42. Pin 10 should be +12V. Pin 9 should be -12V. Pin 2 should have a square wave from 0V to 12V.
Not quite sure what's going on with this circuit. I agree that the UAF42 should work well with the other circuits as I have them connected. I have verified all the connections and have also verified the +/-12VDC, gnd and the square wave coming into pin 2 using an o'scope. I have noticed that pin 7 is -12VDC. (I have also tried another UAF42 to rule out a bad chip). But if I connect the UAF42 to a separate supply, I get the sine wave output on pin 7, however the output rides on a negative output voltage. I am using a breadboard and thought that may have been an issue due to a connection problem so I relocated the UAF42 to a different section with the same results. I may just have to actually solder all of the components to insure proper connections.
On a similar note, I constructed a similar circuit but utilized a CD74HCT390 versus CD4017. I used the same +/-12VDC and gnd. This circuit worked with all IC's connected to the same supply voltages. The only reason I wanted to use the CD4017 is the higher supply voltage and higher output voltage range.
Hummm? I can't explain it. I still believe it's a hookup issue of some type. It's happened to us all. :)
Further diagnostics: Connect o-scope ground to pin 11 of the UAF42. Measure the voltage on the ground of the 4013 (should be zero). Supply pin of 4013 should be +12.
Bruce
It turned out to be a problem with an entire section of my breadboard. Not sure exactly what happened with that particular section. Voltages, signals, etc. looked fine but when I placed the UAF42 on an entirely new section, it worked fine. Thanks for your help.
Good. I'm glad you found it. As I said, it's happened to us all.