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matthewpoage

  • Date JoinedFeb 21, 2008
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Orangeboard

Whats up man i really like this circut and i am building it for a class project there is one symbol on there that i dont know what it is its on LM386 chip that connects pin 1 and 8 it looks like GNGN8 i would really like it if you could tell me what that is?

Thanks!
matthewpoage (author)  l;ashdgals;hg4 years ago
I am glad you like the project. The 1 and 8 pins on the LM386 control the gain of the amplifier. Look at the datasheet and you will see various configurations of resistors and capacitors strung between pins 1 and 8 to create various levels of gain. Usually I have just left these pins unconnected (lowest gain). With an older or weaker MP3 player you will probably want some gain. A wire connecting the pins will create the highest gain. Experiment with configurations. You can also put a potentiometer in to give something of a volume control. The GNGN8 is actually the names I gave to the pins, except that they overlap and mask each other. They are GN1 and GN8 (GN for gain). Hope this helps. Let me know if you have other questions.
constructor5 years ago
Hi, I have started going through your schematic and I noticed that you have a D2 (1N4001) listed but I don't see it in the listed parts nor is it present in the picture of your assembled board. Is the schematic an older / newer design compared to the assembled board? Also on the left top corner coming out of the B1-B I notice that you show a value of +9 V is that correct? Looking forward to your answer. Regards, Michael
matthewpoage (author)  constructor5 years ago
Good catch on both. The +9 for the battery is left over from when the ATS was powered directly from a 9V battery. The upper half of the schematic is for the circuit that bumps a single AA (1.2V for rechargeable) battery up to the 5V necessary to run the amplifier portion. The whole thing is now just powered from the AA battery. Similarly, the D2 1N4001 diode was in place when the ATS had a 9V supply to prevent reverse current if someone put the 9V battery in backwards. Since (I believe, hope, and it has been my experience) that the MAX756 chip outputs 5V and deals responsibly if you put a battery in backwards, I replaced the diode with a jumper (see note in step 5 Soldering Parts to PCB). This eliminates the voltage drop by diode which supplies slightly higher voltage to the amplifier. Hope this helps. Let me know if you have other questions.
constructor5 years ago
Thanks! That worked. I noticed that my Firefox at work did show this I but the one at home did. I will keep you posted as I progress.
constructor5 years ago
Hello, great Altoids instructions! I'm in the process of getting the parts together. I was wondering where I can find the circuit layout for the transfer onto the copper. You have a picture of it in your instructions but I'm not sure if this what should be used. In case if it is on their and I missed it I would high appreciate if you could point me to the right spot. Thanks. Michael

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