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 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
LM386
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MickeyDelp



Joined: Feb 26, 2010
Posts: 42
Location: Austin TX
Audio files: 1

PostPosted: Fri Feb 26, 2010 9:33 am    Post subject: LM386
Subject description: Simple amplifier does not have fade out effect
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Hello all.
I have breadboarded a WSG and added a simple LM386 amplifier (see attached). It sounds OK. However, when I use it, it does not give me the "Twilight Zone" fade out effect on power down. This seems a bit odd to me since it works fine using a Radio Shack mini amplifier (which is at least 25 years old, BTW) which is also based on the LM386. Radio Shack was kind enough to print the schematic inside the amp case (see attached).

So, my question is: do I have to add all the other parts to make the LM386 a usable amplifier, or is there a simpler solution?

Thanks in advance,
Mickey


RadioShack Amp Schematic.JPG
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RadioShack Amp Schematic.JPG



Mims Amp Schematic.JPG
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Forest Mims' LM386 based amplifier schematic.
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Mims Amp Schematic.JPG



Last edited by MickeyDelp on Fri Feb 26, 2010 10:19 am; edited 1 time in total
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RF



Joined: Mar 23, 2007
Posts: 1495
Location: Northern Minnesota, USA
Audio files: 28

PostPosted: Fri Feb 26, 2010 10:01 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Mickey -
I'm just guessing - but does the amp you built run off the same power supply as the wsg, and switching off the wsg also switches off the amp?

If so, I'll say the current draw of the amp just quickly drains the caps in the wsg that are responsible for the 'normal' wsg power down noises...

Zat make any sense?

Try a separate power supply on the amp and see if that 'cures' it.

bruce
EDIT - Oh - Welcome to the forum! welcome

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"I want to make these sounds that go wooo-wooo-ah-woo-woo.”
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MickeyDelp



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PostPosted: Fri Feb 26, 2010 10:13 am    Post subject: Reply with quote  Mark this post and the followings unread

Doh! Embarassed

That was the problem. It works fine now. Thanks, Bruce - for both the answer and the welcome.
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RF



Joined: Mar 23, 2007
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PostPosted: Fri Feb 26, 2010 10:30 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm glad it was as easy as that Smile

Make some noise and record it, take some pics and share them... Love to hear and see what you are doing....

bruce

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"I want to make these sounds that go wooo-wooo-ah-woo-woo.”
(Herb Deutsch to Bob Moog ~1963)
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MickeyDelp



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Posts: 42
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PostPosted: Fri Feb 26, 2010 11:02 am    Post subject: Reply with quote  Mark this post and the followings unread

Here is a pic of the breadboard. You can see the little push button at the top that feeds/cuts power to the 40106 while letting the amp run. Thanks again for the fix.

The WSG is an amazing circuit. Such a variety of sounds from something so simple. I am sure I will be playing with this one for a while. I will post some sounds when I get a couple of good ones.


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