Guest nanop Posted July 13, 2006 Report Share Posted July 13, 2006 Hi, I'm looking to build a Audio/Sound Amplier for my Digital Metronome so the sound from it can be louder. I haven't found any that suits my need. The amplifier has to be portable( So it uses Batteries), and best if it contains no ICs ( To keep it simple). Any Ideas? Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 13, 2006 Report Share Posted July 13, 2006 An LM386 is an IC that is inexpensive and works very well with only a few extra parts.If you don't want an IC then a simple amp will have only 3 transistors, doesn't work as well as an LM386 IC, has more parts and costs more. Quote Link to comment Share on other sites More sharing options...
Guest nanop Posted July 13, 2006 Report Share Posted July 13, 2006 Thanks for the 2 schematics. I think I'll build the one with the IC. I have a question about the supply voltage. In the schematic, it said +10volts, so could I use a 9v battery?And, where do I connect the ground of the Input, and the Speaker? Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 13, 2006 Report Share Posted July 13, 2006 I have a question about the supply voltage. In the schematic, it said +10volts, so could I use a 9v battery?The LM386 amp works with a supply voltage from 5V to 12V. 9V is fine and the max power will drop as the battery voltage drops as it is used.And, where do I connect the ground of the Input, and the Speaker?The ground connections are all connected together.I have it detailed here: Quote Link to comment Share on other sites More sharing options...
Guest nanop Posted July 13, 2006 Report Share Posted July 13, 2006 Thank You very much Audioguru for helping me on this!I'm going to build this as soon as I have all the parts. :) Quote Link to comment Share on other sites More sharing options...
Guest nanop Posted July 13, 2006 Report Share Posted July 13, 2006 Hi again, :)I built the thing on a breadboard t try it out first. Overall, it worked really good at amplifying the input source and being small/portable, but it also had some outside noise coming out from the speaker. When I put my hand around the wires and components, it also generated a tone, noise on the speaker. Do u know y? is this because its on a breadboard with long leads, tracks, and wires?I also found another amp that uses a 546 Power Amp IC. This also had the same problems(noise). Do u also know the noise:sound ratio of any of these?-Thanks Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 13, 2006 Report Share Posted July 13, 2006 The input to an amplifier needs shielded audio cable.The connections of the circuit must be with very short wires so a breadboard is not good. The wires act like "antennas" and pickup mains hum and buzz and other interference. Quote Link to comment Share on other sites More sharing options...
Guest nanop Posted July 23, 2006 Report Share Posted July 23, 2006 Hi again Audioguru,About the audio/sound amp, I found out about 2 other ones that use the LM386, but has gains of 50 and 200. The schematics are below. I'm not sure about what the optional bypass does?and what type/value capacitor to use?Thanks again :) Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 23, 2006 Report Share Posted July 23, 2006 I'm not sure about what the optional bypass does?and what type/value capacitor to use?Look in the datasheet. It shows that a 10uF to 47uF electrolytic bypass capacitor reduces hum from a mains power supply 100 times less. It also reduces distortion when a battery that is powering it is low. Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 23, 2006 Report Share Posted July 23, 2006 You don't know about datasheets?Manufacturers post them on their websites. They have all kinds of information about the parts and applications for them. Many even have pcb designs for the parts.You can key the part numbers into Google for datasheets, but I get most of mine from www.datasheetarchive.com .Here is the datasheet for the LM386:LM386.pdf Quote Link to comment Share on other sites More sharing options...
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