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EvilSmurf 6th December 2012 11:04 AM

Headphone guitar op amp beginner
Hello everyone
I am new to this forum and electronics so I hope I won't post anything wrong, sorry if I do...
I found this ( on the forums here.
I have been looking for something like this for quite a while and was very excited to find it.
So now I really want to build one but I have a couple of questions due my lack of electronic experience. I huess that since the original thread is pretty old ill star a new one. If anyone can help me out here that will be great.
The scheme there seems like something I can handle however I don't quite understand the opamp part and all the links at the thread are dead. I tried googling the tl082p but couldn't find one. I did however found plenty of different tl082 with various letters after the number. Does anyone have an idea which one should I use?
The schematic has various 9v+ places should I connect them straight to the battery? Does the 9vpad means connecting it to the 9v+ too at that place by the switch? All the ground suppose to go to 9v- , am I correct? Also there is a place by guitar input that has gpad- and + ends those are mystery to me...
I looked both at the finished pic and the board layout but couldn't figure out what to do. Also I will probably build something less compact but I guess I'll manage doing that on a bigger board.
If I had chance to contact the original designer I would have asked him all the questions but I don't know how so if anyone can help me out with this I will be most thankful.

Mooly 6th December 2012 12:13 PM

I take it you mean this circuit,

The TL082 is available in different types of package such as 8 pin DIL or SMD. These are reflected in the full device number. All will work but you (I assume) want the 8 pin DIL version which is the biggest and easiest to work with. So you want something like a TL082CN or CP
CPC - Over 100, 000 products from one of the worlds leading distributors of electronic and related products. | CPC

It all seems to run on a single 9v supply so yes, all the 9 volt points go to the battery positive. The battery "negative" we call ground or zero here. The g+pad is a bit misleading. That point is simply the audio input to the TL082. The Gpad- is simply audio ground.

And if you are still not sure :) then ask.

EvilSmurf 6th December 2012 12:29 PM

!!! Wow man thanks!!! You are amazing! Thanks for clearing this all out for me and so fast!!! I had hard time understanding all this... So to be 100% sure the circles marked as 9vpad and gndpad are just another 9v+/- ? and the rest of 9+ circles connect to battery without switch between them right?
Going to get the pats now will post once I put it all together.

Mooly 6th December 2012 07:03 PM

Thats it ! and your very welcome :)

(And if your building this on veroboard or making your own PCB then you can always use the SINGLE version of these opamps, the TL081. Just check the data sheet for the slightly different pin out. Also the TL072 opamp is the better specification device with slightly lower noise and 100% compatable. The TL071 is the single version)

EvilSmurf 7th December 2012 09:08 PM

Thanks again! You helped me a lot!
That advise and explanation about opamps is great! I think I will just check couple of variations and see what happens. The thing about the parts is a bit clearer for me now.
I will definitely try the one you suggested

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