PGA2310 & NE5532 get hot?

sergiusz · 18th December 2005, 07:40 AM

Hello,

I built a small test circuit using a PGA2310 and a NE5532 input buffer. The analog part of the PGA2310 and the NE5532 are powered with +-15V using LM317/LM337.

When I touch the NE5532 it gets pretty warm, tha PGA2310 gets hand-warm.

Is this behaviour normal?

Thanks in advance,
Serge

Netlist · 18th December 2005, 08:28 AM

A schematic would be handy, if possible.

/Hugo

sergiusz · 18th December 2005, 09:24 AM

Sure,

attached is the schematic of the PGA and NE5532 part.

R3 & R6 are marked 0 and R4 & R7 nc (not connected), because I currently let the NE5532 run without any gain.

SV3 is the "bus" connector to the atmel controller. SV1 is the output bus for daisy chaining with a 74hc595.

Thanks !

sergiusz · 18th December 2005, 09:27 AM

And here is the PSU attached.

Nothing fancy at all :-)

Netlist · 18th December 2005, 10:09 AM

Much depends on the environment and the definition of warm and hot.
Looking at the datasheet the dissipation is 1200 mW max.
I nothing is oscillating, I would believe this is fairly normal.

/Hugo

sergiusz · 18th December 2005, 10:40 AM

Hmm ... oscillation, that may be it ... I have to admit I have no bypass caps on the 5532, shame on me.

On another thread I read that a small series resistor may be needed on the output of the opamp too.

I did not assume oscillation because the sound is not distorted.

Thanks for the hint anyway. I'll rework my design and improve the buffer stage,

Sorry for the newbish questions ;-)

Bye,
Serge

Jocko Homo · 18th December 2005, 07:51 PM

Just because it doesn't sound distorted.............

Get your 'scope out. Hope you have one. "Sounds" like you will need it.

(Sorry.......that was too obvious a pun to pass by.)

Jocko

sergiusz · 18th December 2005, 08:12 PM

Hi,
Sorry .. I'm a pretty newbie at this. I put bypass 100n caps from the supply pins to ground as well as 250Ohm resistors on the output. Well, the ne5532 still gets warm.

I do not have a scope unfortunately. Is there any other method of detecting oscillation?

Thanks,
Serge

Netlist · 18th December 2005, 08:39 PM

A trick might be to calculate the power consumption at idle and look if it's within specs. If not…
Also, assuming you have taken the necessary precautions to prevent the circuit from oscillating you could be on the safe side.
But then again, you are never sure without a scope. Ebay might be your friend for your next investment.

/Hugo

alfsch · 20th December 2005, 10:52 AM

5532 gets warm, thats normal...30..35°
and the sound? idle noise?

18th December 2005, 07:40 AM	#1
sergiusz diyAudio Member Join Date: Dec 2003 Location: Berlin	PGA2310 & NE5532 get hot? Hello, I built a small test circuit using a PGA2310 and a NE5532 input buffer. The analog part of the PGA2310 and the NE5532 are powered with +-15V using LM317/LM337. When I touch the NE5532 it gets pretty warm, tha PGA2310 gets hand-warm. Is this behaviour normal? Thanks in advance, Serge

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18th December 2005, 08:28 AM	#2
Netlist diyAudio Moderator Join Date: Jan 2003	A schematic would be handy, if possible. /Hugo

18th December 2005, 10:09 AM	#5
Netlist diyAudio Moderator Join Date: Jan 2003	Much depends on the environment and the definition of warm and hot. Looking at the datasheet the dissipation is 1200 mW max. I nothing is oscillating, I would believe this is fairly normal. /Hugo

18th December 2005, 10:40 AM	#6
sergiusz diyAudio Member Join Date: Dec 2003 Location: Berlin	Hmm ... oscillation, that may be it ... I have to admit I have no bypass caps on the 5532, shame on me. On another thread I read that a small series resistor may be needed on the output of the opamp too. I did not assume oscillation because the sound is not distorted. Thanks for the hint anyway. I'll rework my design and improve the buffer stage, Sorry for the newbish questions ;-) Bye, Serge

18th December 2005, 07:51 PM	#7
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	Just because it doesn't sound distorted............. Get your 'scope out. Hope you have one. "Sounds" like you will need it. (Sorry.......that was too obvious a pun to pass by.) Jocko

18th December 2005, 08:12 PM	#8
sergiusz diyAudio Member Join Date: Dec 2003 Location: Berlin	Hi, Sorry .. I'm a pretty newbie at this. I put bypass 100n caps from the supply pins to ground as well as 250Ohm resistors on the output. Well, the ne5532 still gets warm. I do not have a scope unfortunately. Is there any other method of detecting oscillation? Thanks, Serge

18th December 2005, 08:39 PM	#9
Netlist diyAudio Moderator Join Date: Jan 2003	A trick might be to calculate the power consumption at idle and look if it's within specs. If not… Also, assuming you have taken the necessary precautions to prevent the circuit from oscillating you could be on the safe side. But then again, you are never sure without a scope. Ebay might be your friend for your next investment. /Hugo

20th December 2005, 10:52 AM	#10
alfsch diyAudio Member Join Date: Jan 2002 Location: augsburg	5532 gets warm, thats normal...30..35° and the sound? idle noise?

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