View single post by Jeff
 Posted: Jan 16th, 2008 04:03 PM
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Jeff

 

Joined: Nov 7th, 2007
Location: Alabama USA
Posts: 127
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 Good job; and great results Frank!  I would like to make a clarification, if I may.  The LM386 is actually a low power audio amplifier, and not an operational amplifier (OPAMP).  There are many differences between the two, but the main difference is that the LM386 has an audio power amplifier built-in to drive a small speaker, when the opamp does not.  The opamp usually requires a dual power supply, such as +15Vdc and -15Vdc, where the LM386 only requires one positive power source. 

Your choice, Frank, in the LM386 was a very good one in this case!  You didn't have to build another power amp to drive your speaker; and the output of the LM386 can drive a very wide range of impedances without having to build another impedance matching device.

For those interested, below is a link to the LM386 technical sheets from National Semiconductor.  If you scroll to the bottom of the sheet, there are some circuit suggestions from National Semiconductor to experiment with.  Since it is a pdf link, you may have to copy it into your browser address field:
web.mit.edu/6.115/www/datasheets/LM386.pdf

Many blessings,

Jeff

Last edited on Jan 16th, 2008 04:06 PM by Jeff