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Schematic Of my Old Portable Headphone Amp

post #1 of 7
Thread Starter 
Lots of folks request copies of my Portable headphone Amp Schematic. hanson Hostes them but I think the link may be forgotten so since I get the Most Requests for This Amp i have attached the schematic I hope it is readable i used a Program Called Vue Print Pro-32 ti Convert the MC-6 File and sometimes that Program is less than Perfect. It is hard for me to Judge Image quality since my vision is not so great.

This is my Origenal Design i made back in 1998 and ran off Two 9 volt batteries The Chip-set are AD-744 Usin Pin 5 as the Output rather than Pin 6 Pin 5 is the OPA's Compensation Pin. By using this Pin rather than the Normal Output Pin 6 of the Opamp the Opamp's output stage is by passed and as sutch no Current source is needed to obtain a Class A output stage since This method Connects the Opamp's Voltage gain Stage Directly to the Buffers Input. This is as Close to discreet Component Performance Obtainable in IC Form. The Output Buffers used are the BUF-634P in the 8 Pin Dip. Not Showen is a Resistor that the User can switch in or out on The bandwidth Pin of the Output BUF-634's This is to allow a Battery saving Low Bias mode or a High Bias Quality Mode. the value of this resistor is 470 Ohms but can be as low as 100 ohms. resistors less than 100 ohms cause the Buffers to Run hotter than i would like with no Heatsink and as sutch the sound suffers. My listening test resulted in the 470 ohm offer an inprovement over no resistor with 100 ohms being Ideal and lower values degrading the sound.

The J-fets are type MPF-4392, J174 or Equiv. the Bipolar transistors are Gen Purpose. Pnp/npn types like the 2N3904 & 2N3906 or 2N2222A and 2N2907 Or equiv. The Zener Diode is 6.3 Volts and the LED is a Blue radio Shack Type.

Oh Well I gess the bmp image was to large to post I give up i sent this to cmoy several times with out a reply and this did not work so i gess just go to hansons site. Please No more emails requesting schematics.
post #2 of 7
i'm still alive, but busy.

here are the schematics

*http://homepage.mac.com/hyungsongnam/


skip the first page, click on "Downloads" on top of the screen, choose the folder named "PPL designs". they are all in there.
post #3 of 7
I would really like to see these designs but my computer tries to convert the downloads to ms word format, how can I get around this and view the circuits.
Thanks
post #4 of 7
PPL's schematics _ARE_ in Word format.
post #5 of 7
Thread Starter 
I have gif and bmp files of these however some of the lines are broken. i dont know why this happend i used vur print pro-32 to convert thes images. ill send them to you hasnam if thay would be useable, in the meantime ill try and get an image of good quality. I put the ones posted on hansons site in word since i could include the documentation. any sugestions?
post #6 of 7
ppl, hsnam = "hanson" you always called me that for some reason.

anyway, the 5 files in the directory above are indeed in .doc, ie, MS Word, format.

because of iDisk software, it's encoded into .binhex.hqx format.

what you need to do is go to www.aladdin.com, and download StuffIt Expander. Then use StuffIt Expander to decode the 5 files in the directory. I will fix that situation eventually.

mac users need not do anything. save the file and it will automatically be decoded after download.
post #7 of 7
Thread Starter 
Sorry for the mixup on your user name I somewhow got hanson on the Brain when it comes to you. BTW the Link above did not work. Boy this would have been alot easyer if cmoy would post these I sent them to him several times over the past few years and he has not even resopnded to my email How rude.
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