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Old 04-14-2017, 2:05 AM
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Default 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
[IMG=http://www.learningaboutelectronics.com/images/LM741_pinout_diagram.jpg]
http://www.learningaboutelectronics....741-op-amp.png
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.
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Old 04-14-2017, 2:24 AM
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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?
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Old 04-14-2017, 8:34 AM
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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.
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Old 04-14-2017, 7:06 PM
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Quote:
Originally Posted by WA0CBW View Post
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.
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Old 04-14-2017, 7:46 PM
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Quote:
Originally Posted by beamin View Post
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.
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Old 04-16-2017, 6:22 AM
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Quote:
Originally Posted by slicerwizard View Post
Yes.


Yes.


Then you should be all set.
Yes. But it didn't work when I did that. Built the circuit twice.
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Old 04-16-2017, 6:18 PM
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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.
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Old 04-17-2017, 9:24 AM
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Quote:
Originally Posted by beamin View Post

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..
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