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04-14-2017, 2:05 AM
 Member Join Date: Jan 2012 Posts: 106
How to wire in plus minus and gnd into opamp chip?

http://www.nteinc.com/specs/900to999/pdf/nte987.pdf

You will see this chip has
+v
gnd
out (x4)
invt in(x4)
noninvt in(x4)
A fourteen pin chip with four op amps inside and
The schematic I'm building off of has both a V+ and V- (single opamp chip)

Does my -9 volts go into the gnd pin? What do I hook up ground to in this circuit? Just the passives and not the chip?
My power supply is a +12,-12 and gnd

I dont want to blow up my chip.
04-14-2017, 2:24 AM
 Member Join Date: Jan 2012 Posts: 106

Or does this chip not need negative voltage? When I plugged it in nothing happened. So would this circuit work by just eliminating the negative voltage all together?
04-14-2017, 8:34 AM
 Member Amateur Radio Join Date: Dec 2011 Location: Shawnee Kansas (Kansas City) Posts: 1,177

You need a +9, -9, and ground. Use two 9 volt batteries connected in series. Ground is the point where the two batteries are connected together.
BB
04-14-2017, 7:06 PM
 Member Join Date: Jan 2012 Posts: 106

Quote:
 Originally Posted by WA0CBW You need a +9, -9, and ground. Use two 9 volt batteries connected in series. Ground is the point where the two batteries are connected together. BB
I think you missed a part of my post:
Why would I do that when my power supply has positive voltage, negative voltage and ground? So i tried it with the negative to gnd pin on the chip and gnd to my passives; nothing. I also tried it without the negative voltage altogether, wiring +12 and gnd. Did I blow the chip? My power supply says it pulls 10mA, so I think thats normal.

Also I tried this again today and hooked up gnd to vcc and +12 to gnd by accident; it pulled 20ma when it was wired backwards. I wired it correctly and it still pulls 10ma. Would that blow it up? Was only backwards for less then a minute.
04-14-2017, 7:46 PM
 Member Join Date: Sep 2002 Location: Toronto, Ontario Posts: 4,459

Quote:
 Originally Posted by beamin Does my -9 volts go into the gnd pin?
Yes.

Quote:
 What do I hook up ground to in this circuit? Just the passives and not the chip?
Yes.

Quote:
 My power supply is a +12,-12 and gnd
Then you should be all set.
04-16-2017, 6:22 AM
 Member Join Date: Jan 2012 Posts: 106

Quote:
 Originally Posted by slicerwizard Yes. Yes. Then you should be all set.
Yes. But it didn't work when I did that. Built the circuit twice.
04-16-2017, 6:18 PM
 Member Join Date: Sep 2002 Location: Toronto, Ontario Posts: 4,459

Test the opamp. Power it with the + and - power leads, then apply control voltages to each amp's + and - signal inputs; the amp's output should swing high or low based on the input voltages.
04-17-2017, 9:24 AM
 Member Premium Subscriber Amateur Radio Join Date: Dec 2002 Location: Lewisville, TX Posts: 647

Quote:
 Originally Posted by beamin snip... Also I tried this again today and hooked up gnd to vcc and +12 to gnd by accident; it pulled 20ma when it was wired backwards. I wired it correctly and it still pulls 10ma. Would that blow it up? Was only backwards for less then a minute.
Reverse voltage can be the kiss of death depending on device. If your power supply is reasonably correct 10ma seems high based on datasheet information of no load and no input at 5v and 30v Vcc.

Usually sample circuits for a device are part of the datasheet to help use the part. Seems like the manufacture not interested. I Goggled looking for a circuit, but didn't find one. Single ended op amps in my opinion get tricky because you don't want negative excursion of the input to go past ground if you are not using a split supply connection.

Mike
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Last edited by mcscanner; 04-17-2017 at 9:30 AM..