For the LM386 you can use national's circuits, see page 5 of the datasheet.
Easy, cheap and fun to build, and also works well on a breadboard so you can goof around with components to see what does what.
Have fun!
http://www.ti.com/lit/ds/symlink/lm386.pdf
Easy, cheap and fun to build, and also works well on a breadboard so you can goof around with components to see what does what.
Have fun!
http://www.ti.com/lit/ds/symlink/lm386.pdf
Suppose for a moment that you like what you end up building and find a use for it. What would be useful to build? TL072 by itself is just a low power opamp. It will do a terrible job of driving headphones and not much else except in an input or filter stage of another amp.
LM386, kind of dinky thing too which has its purposes but you could build a significantly more powerful amp at minimal extra expense and complexity.
So the question is how many watts into what speaker load (or what general purpose is the same), and at what general price range for just the amp without considering the case, connectors and other hardware?
I suppose a beginner project would be better if safer, if dealing with power rail voltages under about 30V rail to rail and using an AC-DC wall wart (unregulated power adapter brick) or batteries for power so you aren't dealing with exposed high voltage mains AC power yet.
Do you have any spare parts you'd like to use to speed up the build or cut costs? Any spare power bricks rated higher than 12VDC? Even if not, how about an 11W/ch stereo chipamp based on LM4752? That's enough power for driving reasonably efficient computer speakers to unlistenably loud levels (if seated nearby) with minimal external part count and expense.
Here's the datasheet for that, http://www.ti.com/lit/ds/symlink/lm4752.pdf
if you just build the whole "System Application Circuit" as-is on page 7 and powered it with an unregulated 12VDC/1A power brick it should bring more satisfaction than LM386 would but at only 12VDC (a little higher in use) it would lie between LM386 and it's 11W rated output power. Costs about $2 more than LM386 though and will need a small heatsink. Digikey is out of the through-hole version but Mouser has some, Mouser Electronics - Electronic Component Distributor LM4752
LM386, kind of dinky thing too which has its purposes but you could build a significantly more powerful amp at minimal extra expense and complexity.
So the question is how many watts into what speaker load (or what general purpose is the same), and at what general price range for just the amp without considering the case, connectors and other hardware?
I suppose a beginner project would be better if safer, if dealing with power rail voltages under about 30V rail to rail and using an AC-DC wall wart (unregulated power adapter brick) or batteries for power so you aren't dealing with exposed high voltage mains AC power yet.
Do you have any spare parts you'd like to use to speed up the build or cut costs? Any spare power bricks rated higher than 12VDC? Even if not, how about an 11W/ch stereo chipamp based on LM4752? That's enough power for driving reasonably efficient computer speakers to unlistenably loud levels (if seated nearby) with minimal external part count and expense.
Here's the datasheet for that, http://www.ti.com/lit/ds/symlink/lm4752.pdf
if you just build the whole "System Application Circuit" as-is on page 7 and powered it with an unregulated 12VDC/1A power brick it should bring more satisfaction than LM386 would but at only 12VDC (a little higher in use) it would lie between LM386 and it's 11W rated output power. Costs about $2 more than LM386 though and will need a small heatsink. Digikey is out of the through-hole version but Mouser has some, Mouser Electronics - Electronic Component Distributor LM4752
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You could buy a set of the upgrade boards for the old Dynaco stereo 120, but add your own 72 volt regulated supply. These boards are based on LM3886's. You can order the super heat sinks (super is a relative word, in comparison with the stock Dynaco heat sinks).
Even if you decide that's not your cup of tea, you may find other valuable information here:
Update My Dynaco
And yes...it's my web site...my apologies in advance for the shameless plug!
Even if you decide that's not your cup of tea, you may find other valuable information here:
Update My Dynaco
And yes...it's my web site...my apologies in advance for the shameless plug!
Sorry for thread jacking. The reason I ask is I have been restoring an old Bryston, finding reliable transistors and the rest of my parts at one place with one payment method is tricky blah blah blah. Anyhow so now I am thinking of replacing the amplifier boards with something newer, etc along the lines of your conversion.
The transformers I have are 70V center tapped (Possibly 77vct) I figured this to be to high for the more traditional gainclone voltage.
I have started looking at other chips etc, although if I could use some LM3886 etc it would be great.
The transformers ares decent, each are labeled 250VA, although the bottom of the amplifier read 960VA, either way they are decent.
This is the really old 3B so I think the gainclone would sound better.
I need to do something high powered to take advantage of the iron etc. I have or I will have to get the transistors etc and restore it like I have been doing.
A gainclone conversion would cost less compared to replacing 8 transistors wit decent ones. I actually only need 2, but ideally I would replace all 8 with similar manufacture date etc.
I noticed they have some 3 channel chips and in the block diagram it looks like internally the op amps get their voltage in series with one another. lol it would be handy to do that with separate chips.
The transformers I have are 70V center tapped (Possibly 77vct) I figured this to be to high for the more traditional gainclone voltage.
I have started looking at other chips etc, although if I could use some LM3886 etc it would be great.
The transformers ares decent, each are labeled 250VA, although the bottom of the amplifier read 960VA, either way they are decent.
This is the really old 3B so I think the gainclone would sound better.
I need to do something high powered to take advantage of the iron etc. I have or I will have to get the transistors etc and restore it like I have been doing.
A gainclone conversion would cost less compared to replacing 8 transistors wit decent ones. I actually only need 2, but ideally I would replace all 8 with similar manufacture date etc.
I noticed they have some 3 channel chips and in the block diagram it looks like internally the op amps get their voltage in series with one another. lol it would be handy to do that with separate chips.
Yes, 70Vac CT = 35-0-35Vac and will give ~+-50Vdc PSU.
This is perfect for a 100W into 8r0 amplifier.
These transformers may just about get you 180W into 4r0.
Actually I was wondering what AndrewT would say.
I was looking at this guys amp with a regulated 35v from ~50v. Roman Black's gainclone amp
I could maybe do something like that, even a bi-amp setup if the space allows.
What would you do with them?
I was looking at this guys amp with a regulated 35v from ~50v. Roman Black's gainclone amp
I could maybe do something like that, even a bi-amp setup if the space allows.
What would you do with them?
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