Monday, 5 December 2016

Dirty Little Secret: Assembly 2

DLS Assembly

Figure below shows a top view of the effect baseboard with 5 potentiometers: Treble, Mid, Bass, Gain, Volume, LED and toggle switch; 3PDT footswitch connected to baseboard with a 6-wire flat cable and 9V battery. 
The 3PDT toggle switch is oversized and it's much taller than potentiometers, in the following version I will probably try to replace it with a lower profile 3PDT slide switch
The enclosure is a 1590B, it is too narrow to properly fit audio jacks and DC jack on the top side, I discovered that a 1550B enclosure is probably more suited to fit the baseboard. I had to file the corners in order to fit the baseboard closer to the top side but still there is a gap.
DLS top side view with enclosure. Baseboard, 3PDT footswitch, 9V battery and 1590B enclosure
 The figure below shows the bottom side with the JFET mezzanine board mounted on baseboard. I had to make some slots in order to plug the mezzanine because of the audio jacks were too deep.
DLS bottom side view with JFET mezzanine mounted 
 The figure below shows the baseboard bottom side with audio jacks (stereo for input and mono for output). FB1 and FB2 are input and output ferrite filters, CF1 is an EMI 9V power supply input filter, D3 is a reverse 9V voltage input protection, U3 is the 9V to 3.3V DC-DC regulator, L1 is switching inductor and L2 is an additional inductor of an LC filter. U4 is a mid-point 1.65V reference voltage. Some resistors and capacitors are part of a Marshall type equalizer filter with treble, mid and bass potentiometers soldered on the opposite side. JP2 is the 2-wire 9V battery connection and JP1 is the 6-wire connection to the true bypass 3PDT footswitch using a 0.1'' pitch flat cable. The two board-to-board connector are used to plug in the effect mezzanine board.
DLS base board bottom side view
The figure below shows the DLS JFET mezzanine board with 3 one turn potentiometers for top JFETs biasing adjust. The DLS JFET effect contains 3 amplifier stages with 2 JFETs each (MMBF4117)
DLS MOSFET mezzanine board
The figure below shows the DLS MOSFET mezzanine board with 3 one turn potentiometers for MOSFET biasing adjust. The DLS MOSFET effect contains 2 amplifier stages and one output buffer stage (Fairchild FDV301VN or Diodes DMG301NU-13)
DLS JFET mezzanine board
The figure below shows a view of the two DLS effect mezzanine boards: JFET on top and MOSFET on bottom.
DLS: JFET mezzanine on top, MOSFET mezzanine on bottom