Audio Amplifier 10706NB - Rockwel(l)

Why are you trying to use an obsolete device?

martin

The project uses uA706 and a substitute that was suggested to me and that I found is 10706NB. BUT, if anybody can suggest me another one, he/she is WELCOME!!!

If you could post the project or a more information on a website, we/I/S.E.D might be able to help.

martin

The project is a Miniamp for guitar by Craig Anderton, published in Electronics Projects For Musician. The project is n.5. Unfortunately I have no idea if I can post here a "jpg" or "gif" scan, so I'll try to draw a layout in ascii characters and post it here (Moderator, can I do it?). I would be happy just to find the 10706NB numbering of the pins.

Bye

Also obsolete it seems.

This 'project' is presumably based on some 20 or so year old article you found ?

As Martin says. Post some more info.

Graham

Date ?

Not here.

That's fine.

You may be disappointed. However the project is very simple so designing a new version is easy.

Graham

Hi! Here is the list of the components and the layout of the mini amp circuit. You can copy and paste it in WinWord and select Font Courier New size 8 for best viewing Bye

============================

R1 : 33 R4 : 47 R5 : 270 R6 : 100 k R7 : 100 k R8 : 470 k R9 : 1M pot audio R10: 1M pot audio

C1 : 20 pF C2 : 390 pF C3 : 0.01 uF C4 : 0.22 uF C5 : 0.22 uF C6 : 0.22 uF C7 : 100 uF electrolytic C8 : 100 uF electrolytic C9 : 100 uF electrolytic C10: 220 uF electrolytic C11: 1000 uF electrolytic

IC: uA706 or TBA641B: pin 1: OUTPUT pin 2,4,9,11,13: NC pin 3,5: GND pin 6: COMP pin 7: INPUT pin 8: FEEDBACK pin 10: RIPPLE BYPASS pin 12: BOOTSTRAP pin 14: + V

o +12V | | | c9 + | +-----+------+---||--+-------+

| | | | |

GND--- | | / >

IN1--+ - | | / > R4

| | | | / >

| >R9 R6 c4 | | / |

| > R10 R7 c5 | 7 | IC \\-12 | + c11 | > | /\\6 | | | GND GND | >R8 |__/8 \\ > | | | > 10| \\ \\ R1 > - | | | | \\ \\_____ > -c6 | | | | \\ | | | | | | | | | c2 | | | c1 _ | - + - + +----||---+ | |

_ | - c7 - c8 | | | /| | | | | - | |/ | | | | | - c3 | o |8 ohm | | | > | | |loudspeaker | | | >R5 | | o | | | | > | | |\\ | +---+------+-----+------+-----------------+----+ \\| | | ---GND -

snip

Incredible piece of ascii art,....

Its a very old design, obviously, there are many better solutions

Hope that wraps well. These are sort of standard products, so just choose one that suits your power rails and power output requirements. I'd suggest TDA2030 as a starting point. It's a good old workhorse

martin

Hmmm..... Well the original circuit was pretty rubbish anyway, e.g. interacting passive mixing with high value resistors ( which will be noisy ).

Now. What is it you *want* to do ? A baby guitar practice amp ? Are 2 inputs important ?

Is it planned to use an ac power supply or do you want it to run off batteries ?

Graham

Just because the OP is being so polite about it, I've re-ASCIImatic'd it - he can't help it that google groups wraps stuff:

o +12V | | | c9 + | +-----+------+---||--+-------+ | | | | | GND--- | | / >

IN1--+ - | | / > R4 | | | | / >

| >R9 R6 c4 | | / | | > R10 R7 c5 | 7 | IC \\-12 | + c11 | > | /\\6 | | | GND GND | >R8 |__/8 \\ > | | | > 10| \\ \\ R1 > - | | | | \\ \\_____ > -c6 | | | | \\ | | | | | | | | | c2 | | | c1 _ | - + - + +----||---+ | | _ | - c7 - c8 | | | /| | | | | - | |/ | | | | | - c3 | o |8 ohm | | | > | | |loudspeaker | | | >R5 | | o | | | | > | | |\\ | +---+------+-----+------+-----------------+----+ \\| | | ---GND And yeah, it does look like a pretty crappy circuit - with modern parts, it'd be almost trivial to do.

Cheers! Rich -

Thanks ;) it took me quite time to draw it down.. !

Graham wrote:

off batteries ?

Yes, I want to build a little guitar practice amp. High fidelty (low distortion) is reccomended but not mandatory. Two inputs are important (I can gig with someone else) I'm planning to power the ampli by a 12V DC wall-wart. When I'm outside (example, camping or seaside) it would be nice anyway to connect it to the 12V battery car plug (or a battery pack). I already bought all the passive components so, I still dream to find the pin numbering of the 10706NB !! Anyway, thank to you, I found a TDA2030 datasheet containing even a PCB board layout !!

Thanks

A guitar requires high Z inputs. You may want to add an input buffer to buffer two inputs, and perhaps a switch to use some distortion, like across diodes or zeners.

greg

On campsite I was in, in Spain, we had a Bagpipe player, who started up at 3am, on the beach, we could hear him for miles, BASTARD. Never did find out who he was

Anyway if you do use a TDA amp, I dont think that it's input impedance is high enough for a geetar, Pooh will probably point you in the right direction. Possibly a TL072 as a voltage follower, an a 1Meg pot.

martin

off batteries ?

It won't be a problem to get perfectly acceptable distortion, noise etc.

Ok.

Ok.

Can you give the link to that just for reference ?

I advise using a separate IC for the guitar inputs as a 'preamp' before the power amp ( maybe TDA2030 ) . So it'll use a few extra bits but not that much.

Let me chew this over. Oh and where do you buy your electronic components ?

Graham

p.s. any ideas for posting binary files. My ISP has dropped support for binary newsgroups so can't use a.b.s.e any more :-(

newsgroups so can't

its a crap site, but it's free

martin

binary newsgroups so can't

Yeah, mine did as well. You with Wannadoo (now Orange) ?. john

Indeed I had a TL072 in mind ( maybe with a little gain ) but followed by typical 10k audio taper pots. You'll be hard pressed to even get 1M these days and probably not in audio taper. 1M makes for extra noise too.

I'm wondering about the best way to arrange a false ground given the single supply rail though. Zener diode probably is simplest.

Graham

I use Plusnet. They dropped the binaries about a month ago. They only had a few even then.

Graham

The part has been obsolete for over 30 years.