Anybody have Tech21 Double Drive "PCB Layout" please

[Songpol T.]

Please send to me too 

Thank.

teeramara@gmail.com

[cbriere]

maybe it helps,

[kusi]

http://forum.musikding.de/yabbse/index.php?topic=4259.0

i made on, and it works. it sounds very good before tube amps, but very ugly before transistoramps!

mfg kusi

[comfortably_numb]

So in this circuit, the points labled (A) are connected together?

How about the diodes off of the transistors?  Connected to what?

Also, do the opamps need power?  Usually, I think, they need 4.5 volts.  Is this VR1 or VR2?  Or are all the necessary connections already on the schematic?

Thanks,
CJD

[chunks717]

     1) So in this circuit, the points labled (A) are connected together?
with A's connected, it will be a very different circuit.
this may be drive one, and drive two, or perhaps the buffered bypass,
but I think not the latter......either way, i would hook up a switch
to connect and disconnect them and see what it does........
     
     2)How about the diodes off of the transistors?  Connected to what?
my guess is ground, but what the hell do I know........

     3)Also, do the opamps need power?  Usually, I think, they need 4.5 volts.  Is this VR1 or VR2?
yes, they will need power.  If you are using TL072's the 9+ goes to pin 8, and ground goes to pin 4.
.....the 10k/10k would be arround 4.5 volts, as the resistors are the same, but you want power for your
op-amps to be 9volt high, and 0v(ground) low. 4.5 is one of your bias voltages, and your signal swings
around this..............................

..........good luck

[aziltz]

i have this pedal, and i think its really great.  But, could someone with some expertise describe whats going on between the last 2 opamps?  with the 2 discrete components and diodes to ground.?

[J. Luja]

I left some simple things off this schematic that I assumed would be obvious to more advanced builders. I was hoping someone would use the ideas to create something new...

anyway, the "A"s connect to eachother, this is the bypass signal path. the fets (used as switches) with diodes connect to the flip flop bypass circuit that I didn't bother drawing (you would leave them out if you were going to build a true-bypass clone) opamps connect to 9v and ground where appropriate and all points labeled VB1 are connected and all VB2 points connect. the specified opamps are required for proper function in this circuit.

hope that helps

[spudulike]

Yes, the two points A are connected together - thats FET bypass switching, controlled by a flip-flop, via the diodes to the gates.

1. A buffered clean signal is always present at point(s) A.
2. Output from the fx is at R18.
3. The two FETS switch alternately (never on together) so you either get clean buffered or fx output.

The preceding op-amps also take care of phase inversion in the preceding stages.

VB1 is 4.5V from the divider R12 & R13, half supply voltage as both resistors are equal.
With 47k, and 20k (R8 & R9 in parallel), I get VB2 as 6.47V

TLC2262s are used for low noise properties. Any dual opamps will work. Personally Id leave the FETs out, build it like this and true bypass it.




<Edit> Posted this while J. Luja was posting his reply 

[Songpol T.]

Very thank all friend.   

[aziltz]

Do you think it would be hard to mod the stock pedal for true bypass?  it does have that pcb mounteed switch and only a spring between the board and the switch on top.