Black Box Buffer  [schematic]

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Black Box Buffer

Postby Mbas974 » 13 Nov 2015, 22:09

Hi this is a buffer box from Italian brand.
Really good quality assembled pedal.

Buffer circuit nothing really new.

What surprise me is the IC2 of TL072 used for LED purpose.
I do not think audio will benefit of this use of the other half IC, can someone explain it ?

a double check to schematic is welcome also !
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Re: Black Box Buffer

Postby mictester » 14 Nov 2015, 03:53

The second half of the TL072 is being used as a battery condition monitor. If the battery voltage falls below a certain point, the LED won't light.
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Re: Black Box Buffer

Postby alexradium » 14 Nov 2015, 13:32

Mbas974 wrote:Hi this is a buffer box from Italian brand.
Really good quality assembled pedal.

Buffer circuit nothing really new.

What surprise me is the IC2 of TL072 used for LED purpose.
I do not think audio will benefit of this use of the other half IC, can someone explain it ?

a double check to schematic is welcome also !
i would say that most buffers are made with a very low output impedance,this one instead is more similar to the guitar out with volume on 10,which seems more accurate tonally (not so bright) and its both good if you plug into a pedalboard or directly to the amp's input.
But in the end it all depends on cables length and so on.

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Re: Black Box Buffer

Postby Intripped » 14 Nov 2015, 15:11

I think there are some minor errors with that schematic,
On the PCB I can clearly see two 2.2M resistors (1M in the schem?), and 1 capacitor is missing: there are 7caps on the PCB and 6 in the schematic.

Mbas, can you post some other pics with caps values please?

Also, in this pic the opamp seems different

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Re: Black Box Buffer

Postby tube-exorcist » 14 Nov 2015, 22:11

Intripped wrote:I think there are some minor errors with that schematic,
On the PCB I can clearly see two 2.2M resistors (1M in the schem?), and 1 capacitor is missing: there are 7caps on the PCB and 6 in the schematic.

Mbas, can you post some other pics with caps values please?

Also, in this pic the opamp seems different

BTW can you verify what is written on the smaller diode ? It is not an 1N4148 - instead it is a zener-diode, probably a C5V1.
IMHO the ouput resistors are 100 Ohm in series and 47k pull down.
and the second 1N4001 is not connected to ground instead one is for the battery the second for the DC-IN jack.
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Re: Black Box Buffer

Postby tube-exorcist » 15 Nov 2015, 14:55

Mbas974 wrote:pls moderator cancel previuos one.

this is the final schematic.


Not really.... R6 + R7 are 2M2
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Re: Black Box Buffer

Postby Intripped » 15 Nov 2015, 15:41

Op-amp in the pic from effectsdatabase is probably an Analog Devices OP275

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Re: Black Box Buffer  [schematic]

Postby Mbas974 » 16 Nov 2015, 09:59

last one
discards all the previous, better moderator remove these to clean the topics (i can't).

..in this stomp IC is TL072, as clearly stated from the picture.
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Re: Black Box Buffer

Postby Intripped » 16 Nov 2015, 11:59

Yes, the IC in your pics is clearly a TL072, I was referring to that unit at effects-database only, but now we know that there are at least 2 versions of this pedal.
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Re: Black Box Buffer

Postby Bernardduur » 13 Aug 2017, 21:18

Here is the schematic of my unit

Masotti - Black box.JPG


Mods: Please change the name of the thread to Masotti - Black box
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Re: Black Box Buffer

Postby snofla1900 » 16 Aug 2017, 12:49

Hi ,


What voltage did you use to power the buffer : 9 volts or more ?

Tia, Alf ( Netherlands)
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Re: Black Box Buffer

Postby Manfred » 17 Aug 2017, 23:46

I made a board clone according the PCB shot and the schematic drawn by Bernardduur.

BlackBoxBufferLayout.JPG


BlackBoxBufferComponents.pdf


BlackBoxBufferPCB.pdf


BlackBoxBufferPCBmirrored.pdf
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