**********************************
*         Balmec boards          *
*         Propeller 1            *
*         Propeller 2            *
*         Propeller 3            *
*         Balsi                  *
*         Bello                  *
**********************************  

Notes:

<Prop1>
Propeller 1 board:

	           Midi in: standard, using an optocoupler
                   Midi Thru/out: using differential drivers to feed long cables

                   Motor control: derived from Whisper design
		   5V power supply on the PCB
                   PCB file: www.logosfoundation.org/instrum_gwr/propellers/PCB/Propeller_Quad_Midi_Buffer.gif
                   Firmware: www.logosfoundation.org/instrum_gwr/propellers/Picworks/Propeller1.bas

                   an improved design, with braking is in the works.
                   PCB file: www.logosfoundation.org/instrum_gwr/propellers/PCB/Propeller1_Quad_Midi_Buffer.gif
                   circuit diagram updated as well. Not yet etched nor produced. [ 29.04.2015]
                   SCH_propeller1.gif

                   13.05.2015: Improved board finished and placed. Some minor changes in the PCB after production.
                               (extra GND pin on Weidmueller connector, for the 12V supply ground)
                               Braking will be active now on note-off commands with a release value.
                   10.02.2022: board repaired: IRL640 exchanged with an IGBT.
                   11.02.2022: PIC firmware upgraded.
                   02.03.2022: 6Ohm gate resistor for the IGBT added. IGBT type is now IKP28N65.

<Prop2>
Propeller 2 board: build up 06-07.03.2015
                   Uses IGBT
                   PCB file: www.logosfoundation.org/instrum_gwr/propellers/PCB/Propeller2_Quad_Midi_Buffer.gif
                   schematic: SCH_Propeller_2.gif
  		   Firmware: www.logosfoundation.org/instrum_gwr/propellers/Picworks/Propeller2.bas
                   An improved version for the schematic drawn out 02.05.2015.
                   new file:
                   SCH_Propeller_2_V2.gif
                   As yet not implemented on the PCB. As we now will be using an 1kVA isolation transformer, the
                   PCB can be somewhat simplified.

<Prop3>
Propeller 3 board: improved PCB and extra LED debug lite.
                   uses IGBT
                   To do: add pull down resistor on IGBT gate. [done]
                   with separate braking control
                   Etched 14.03.2015 
                   Programmed 17.03.2015, version 1.0
                   PCB file: www.logosfoundation.org/instrum_gwr/propellers/PCB/Propeller3_Quad_Midi_Buffer.gif
		   Firmware: www.logosfoundation.org/instrum_gwr/propellers/Picworks/Propeller3.bas
                   An improved version for the schematic drawn out 02.05.2015.
                   new file:
                   SCH_Propeller_3_V2.gif
                   As yet not implemented on the PCB. As we now will be using an 1.6kVA isolation transformer, the
                   PCB can be somewhat simplified.
                   Newly designed board produced. 06.05.2015
                   Firmware revised. Now gradual braking will only happen on note-off + release byte.

<Bello>:
MidiHub board: has power on relay on board.
               Etched 14.03.2015
               PCB file: www.logosfoundation.org/instrum_gwr/propellers/PCB/Midi-Hub-2015-03.gif
               For further production, some errors and correction were remedied in the file
               Midi-Hub-2015-04.gif

Balmec bells 12-output board:
               Version 1.0: design date: 17.03.2015
               Outputs in groups of 2. Each group can have a different positive voltage.
 	       PCB file: www.logosfoundation.org/instrum_gwr/propellers/PCB/Balmec-bells_000.gif	
               One copy produced. PCB lay out improved.
               For further boards use the file: (Version 1.1: design date 26.03.2015)
               www.logosfoundation.org/instrum_gwr/propellers/PCB/Balmec-bells.gif
               Two of these produced 29.03.2015.
               06.05.2015: sofar. no problems encountered.