Tube drive

[jhabib]

http://analogguru.an.ohost.de/193/schematics/Chandler_TubeDriver.gif

Hey,
I am sort of new to stomp box building.  I have built alot of pedals  but all the ones i built were for someone else and i was following a layout diagram, therefore never understanding the circuits myself.  I want to endeavour to try to built a chandler tube driver but i need help knowing what this schematic is saying and how to translate it into building a pedal.  I would like to know how to identify whats happening in the circuit.  Again, i am good a soldering and know how to wire pots, jacks, etc.... i just never UNDERSTOOD what i was doing.  Any help would be appreciated.

Thanks

[PRR]

> what this schematic is saying

Do you know ANY electricity or electronics? This is a hodge-podge plan using concepts from every decade of the 20th century.... it is unlikely anybody can teach it to a beginner with zero theory background in one or many forum messages.

OP1 buffers the input from whatever happens inside, so that you can get a clean bypass.

OP2 amplifies-up the signal zero to nearly 500 to 1.

V1a amplifies about another factor of 20.

V1b amplifies about another factor of 20.

So is we put 0.1V signal in, it should be amplified-up to 0.1V*500*20*20 or 20,000 Volts.

But V1b is only fed total 25.5V of power, can't make any more, will probably make more like 1V or 2V of output.

If the ideal signal is 20,000V and the actual signal is 2V, we may say approximately that we get 99.99% distortion and 0.01% original signal. i.e. the signal is totally trashed. However the trash is directly related to the signal, and the ear hears pitch and weight information.

Or we can turn-down OP2 to lower gains and have "only" 99% distortion and 1% original signal.

I don't think, with those values, it can be dialed-down to "small" distortion. I think it is a FUZZ!-only box.

After the meat-grinder, an odd re-connection of a standard Fender Tonestack cuts everything down yet allows bass and treble to be "boosted" (actually less-cut). And a final knob lets you adjust the result so your main amplifier won't gag.

If that's not ringing any bells, pick something less "clever" to start your studies.

> how to translate it into building a pedal.

You have a good schematic. Print it big. Put parts on it. Many resistors and caps can just be put like in the schematic. OP1 OP2 are both in one chip and the pin-out is nothing like how the schematic is drawn. Drop the chip somewhere in the middle and "bend the lines" (wires) to get where they have to go. The tube is a different re-lay-out problem because it is round and large. I suggest you look at 1950s-1960s Fender amplifiers. They put resistors and caps on a board, tube sockets on the chassis, and ran wires over. In this case there would only be four wires from board to socket.

Once you know how to connect it all, you probably want to slide small parts closer to save space and board-cost. Just imagine the lines are rubber, and may be shortened or bent as needed, but should probably be run simple and direct.

The notes reference a PCB. I think copying a PCB is cheating, but I always look at how someone else did it, for ideas I might or might NOT want to follow.

[jhabib]

Hey man thanks alot!  Like I said, following a layout diagram did not teach me much, but i bulit everything from tubescreamers, to compressors, to fuzzes, even moded some pedals.  Just trying to understand what i am doing now and I think the best way would be to just do it! Again, thank you so much for your contribution!

[KazooMan]

Check out this previous thread:

http://www.diystompboxes.com/smfforum/index.php?topic=85945.0

Near the end you will see a link to another forum where there is a long running thread with tons of information on building a tube drive.

One important point:  If you have never worked with line voltage before, be very careful. 

Also, the most commonly used pcb is a double sided board.  A bit tricky to align the sides for the transfers prior to etching.  Also you need to be careful how you populate the board so you don't cover up any pads you need later and there are some pads that do not get components, they just get a wire through them to connect the two sides of the board.

[twabelljr]

You can gain a pretty good (very good!) understanding of what happens in a circuit while following a schematic by reading the "Technology of the..." articles at GEOFEX. Link at top of page. There is another article there called "What Are All Those Parts For?" that is helpful.