Looking for an op amp

J

Jimmy

Guest
I need an op amp that can handle +- 28 volts rail to rail. I plan to drive a
couple of transistors in an emitter follower configuration to build a small
audio amp.
TIA
 
On Sun, 17 Aug 2003 09:54:15 GMT, "Jimmy" <Gfender@carolina.rr.com>
wrote:

I need an op amp that can handle +- 28 volts rail to rail. I plan to drive a
couple of transistors in an emitter follower configuration to build a small
audio amp.
TIA

I don't know an op amp that will do it, but if your into audio amps
Click to expand...
and want it to sound good, you are looking for more than just the rail
to rail voltage - like rise time and noise figure. Many good audio
amps would need a differential output amplifier to drive both halves
of the complementary symmetry output stages

Design with discrete parts, you can probably do it better than an op
amp. (build the op amp out of discrete parts?)

If you're concerned with saving time, why not use one of the
prepackaged audio modules from National?

Power op amps run high supply voltages, but there's no need to add an
output stage and their audio specs aren't always the greatest.


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On Sun, 17 Aug 2003 09:54:15 GMT, "Jimmy" <Gfender@carolina.rr.com>
wrote:

I need an op amp that can handle +- 28 volts rail to rail. I plan to drive a
couple of transistors in an emitter follower configuration to build a small
audio amp.
TIA

LM12 does it . . . +/- 40 volt supply . . . op amp.
Click to expand...

TO3 case, will output +/- 36 volts single ended (not a differential
output amp) It can be used to drive up to 150 watts into 4 ohms
without further power amplification.


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Built one like this once before, wasn't a great amp but made a nice PA amp.
I was going to build one for my auctioneer friend. I had the amp for a long
time before I sold it, just cant remeber the op amp I used . Pretty sure it
was an ECG unit, ECG/SK was the only thing the parts jobber sold. Dont have
an ECG book anymore though. Real simple circuit, a complimentary pair of
Darlington transistors used on the output. LM12 sounds like it may be what I
want.
"default" <R75/5@defaulter.net> wrote in message
news:1gh2kv8lj7iid3v8eaom6mb57p6bb61vmm@4ax.com...
On Sun, 17 Aug 2003 09:54:15 GMT, "Jimmy" <Gfender@carolina.rr.com
wrote:

I need an op amp that can handle +- 28 volts rail to rail. I plan to
drive a
couple of transistors in an emitter follower configuration to build a
small
audio amp.
TIA

LM12 does it . . . +/- 40 volt supply . . . op amp.

TO3 case, will output +/- 36 volts single ended (not a differential
output amp) It can be used to drive up to 150 watts into 4 ohms
without further power amplification.


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Click to expand...
 
lm12 doesnt look so good after seeing the price, ouch.
"default" <R75/5@defaulter.net> wrote in message
news:1gh2kv8lj7iid3v8eaom6mb57p6bb61vmm@4ax.com...
On Sun, 17 Aug 2003 09:54:15 GMT, "Jimmy" <Gfender@carolina.rr.com
wrote:

I need an op amp that can handle +- 28 volts rail to rail. I plan to
drive a
couple of transistors in an emitter follower configuration to build a
small
audio amp.
TIA

LM12 does it . . . +/- 40 volt supply . . . op amp.

TO3 case, will output +/- 36 volts single ended (not a differential
output amp) It can be used to drive up to 150 watts into 4 ohms
without further power amplification.


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Click to expand...
 
Yeah, the LM12 is too old to be inexpensive. There are a lot of cheap
amp modules out now, it hardly makes sense to roll your own for
something like a Public Address application.

Look at the LM3886, It is capable of 65 watts, should be under $15,
and its got some pretty impressive specs along with a self- protected
output stage.

Similar amp from Edlie Electronics for 70 watts, with heat sink and
everything but the supply in kit form, Part # DP5011-9 / 80-052,
$28.95. Works from a single 12 volt source - that's a good trick! No
web site - paper catalog

A listing of electronic suppliers for the hobbyist
http://www.eskimo.com/~billb/supliers.html#surp4



http://www.dckits.com/audio.htm Is the DC electronics site - audio
kits, the lm3886 kit they offer is $30 for stereo (two LM3886 modules)
65 watts per channel bridgeable for 135 watts into 8 ohms. They don't
put out a paper catalog these days but the IC module was $9.75 when
they did - they still sell components but you have to request a quote.


On Tue, 19 Aug 2003 05:40:16 GMT, "Jimmy" <Gfender@carolina.rr.com>
wrote:

lm12 doesnt look so good after seeing the price, ouch.
"default" <R75/5@defaulter.net> wrote in message
news:1gh2kv8lj7iid3v8eaom6mb57p6bb61vmm@4ax.com...
On Sun, 17 Aug 2003 09:54:15 GMT, "Jimmy" <Gfender@carolina.rr.com
wrote:

I need an op amp that can handle +- 28 volts rail to rail. I plan to
drive a
couple of transistors in an emitter follower configuration to build a
small
audio amp.
TIA

LM12 does it . . . +/- 40 volt supply . . . op amp.

TO3 case, will output +/- 36 volts single ended (not a differential
output amp) It can be used to drive up to 150 watts into 4 ohms
without further power amplification.


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Click to expand...


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Thanks, found my notes on the one I built years ago. I used an ECG 925.
Looks like I will have to crank the power supply back a bit.This one will
only handle +- 22 volts rail to rail. Hope I can still get them. Thanks to
my well supplied "junk box" a 24' by 24' two story garage I havent had to
buy a part in years, . Well not at the local parts store anyway, but dont
think I have this one.


d"default" <R75/5@defaulter.net> wrote in message
news:hvs4kv036gt81fte934h13u9b1qoksfo8l@4ax.com...
Check out:
http://www.qkits.com/serv/qkits/qkitscat/catalog.asp?Page=4&ccat=AUDIO

I don't have any experience with this company, but the amp and price
look pretty good.


On Tue, 19 Aug 2003 05:40:16 GMT, "Jimmy" <Gfender@carolina.rr.com
wrote:

lm12 doesnt look so good after seeing the price, ouch.
"default" <R75/5@defaulter.net> wrote in message
news:1gh2kv8lj7iid3v8eaom6mb57p6bb61vmm@4ax.com...
On Sun, 17 Aug 2003 09:54:15 GMT, "Jimmy" <Gfender@carolina.rr.com
wrote:

I need an op amp that can handle +- 28 volts rail to rail. I plan to
drive a
couple of transistors in an emitter follower configuration to build a
small
audio amp.
TIA

LM12 does it . . . +/- 40 volt supply . . . op amp.

TO3 case, will output +/- 36 volts single ended (not a differential
output amp) It can be used to drive up to 150 watts into 4 ohms
without further power amplification.


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Click to expand...
 
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