Need op-amp help

preiter · 3rd June 2006, 04:11 AM

I've started playing with op-amps in hopes of making myself an active crossover.

I'm using the NE5532 from TI.

Currently, I'm just trying a simple non-inverting buffer. Out is shorted to -in, signal input goes to +in with a 1k resistor between +in and signal ground.

pin 4 goes to power ground, pin 8 to Vcc (about 12 volts).

Here's the weird part. If I connect my output (to the amp) to pin 7 (the op-amp output), it sounds badly distorted. But if I hook it up to pin 8 (VCC) it comes out strong and clear. If I hook my meter, it shows a short between pins 7 and 8, but only in one direction (some sort of output protection diode?) and only when the part is powered.

What am I doing wrong that the op-amp is putting output on the power pin?

Leolabs · 3rd June 2006, 04:39 AM

Hi preiter,you are running the opamp at single supply only,you should study about single supply configuration before moving on.

preiter · 3rd June 2006, 05:29 AM

I tried it both with +12V and Gnd and +12V / -12V. Both produced the same result.

The NE5532 pinout specifies pin 4 as Gnd. But I tried both.

Also tried a 10uF bypass cap between Vcc and Gnd pins, various supply voltages, and a different power supply.

preiter · 3rd June 2006, 06:12 AM

figured it out.

connecting power supply ground to the signal ground helps a lot

dgaxeman · 3rd June 2006, 09:20 PM

try a lm 358 single supply op amp or config the 5532 as a single supply

Ivo_Hristev · 5th June 2006, 01:15 PM

Try reading this one - I think you`ll find the answer of yor question:
http://focus.ti.com/lit/an/slod006b/slod006b.pdf

3rd June 2006, 04:11 AM	#1
preiter diyAudio Member Join Date: May 2006	Need op-amp help I've started playing with op-amps in hopes of making myself an active crossover. I'm using the NE5532 from TI. Currently, I'm just trying a simple non-inverting buffer. Out is shorted to -in, signal input goes to +in with a 1k resistor between +in and signal ground. pin 4 goes to power ground, pin 8 to Vcc (about 12 volts). Here's the weird part. If I connect my output (to the amp) to pin 7 (the op-amp output), it sounds badly distorted. But if I hook it up to pin 8 (VCC) it comes out strong and clear. If I hook my meter, it shows a short between pins 7 and 8, but only in one direction (some sort of output protection diode?) and only when the part is powered. What am I doing wrong that the op-amp is putting output on the power pin?

3rd June 2006, 06:12 AM	#4
preiter diyAudio Member Join Date: May 2006	never mind figured it out. connecting power supply ground to the signal ground helps a lot

3rd June 2006, 09:20 PM	#5
dgaxeman diyAudio Member Join Date: Feb 2006 Location: usa	lm358 try a lm 358 single supply op amp or config the 5532 as a single supply

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3rd June 2006, 04:39 AM	#2
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	Hi preiter,you are running the opamp at single supply only,you should study about single supply configuration before moving on.

3rd June 2006, 05:29 AM	#3
preiter diyAudio Member Join Date: May 2006	I tried it both with +12V and Gnd and +12V / -12V. Both produced the same result. The NE5532 pinout specifies pin 4 as Gnd. But I tried both. Also tried a 10uF bypass cap between Vcc and Gnd pins, various supply voltages, and a different power supply.

5th June 2006, 01:15 PM	#6
Ivo_Hristev diyAudio Member Join Date: Dec 2004 Location: Sofia	Try reading this one - I think you`ll find the answer of yor question: http://focus.ti.com/lit/an/slod006b/slod006b.pdf

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