8.2V = 1N4738A 5.1V = 1N4733A The “A” on the end is optional.
Both work fine, the “LF” version is a low voltage version.
Although it looks good on paper, there is a bug that prevents back-to-back interrupt driven transfers on the serial port. This makes it unusable for MIOS. The 18F4520 has been tested and it is confirmed that it does not work due to this bug. Microchip are aware of this bug but it is not, and may never be resolved.
The whole MB works on 5V, so all Caps should be at about 16V or higher. It doesn´t matter if you go higher.
1/4W (.25watt) or higher will work fine for everything midibox, unless otherwise noted.
Resistors can be installed in any direction.
Smaller value capacitors (i.e. usually under 1 uF) generally have no polarity. Anything above 1 uF is typically an electrolytic capacitor, and it will have a polarity marking. Most often the “-” side is marked with a big stripe, although sometimes it’s the “+” side that is marked. (Strangely, the “+” side seems to be marked on capacitors made in U.S.A.)
Diodes absolutely must be installed in the right direction. Diodes have a stripe on the cathode side.
Most other components have some sort of mark as to their correct orientation. IC’s will have a dot, transistors have a flat side, LEDs have a flat side (and the two leads will be different lengths).
You can substitute four 1N4001 (or any of the 1N400X series) for the bridge rectifier, they will handle more than enough current.
Crystals with parallel cut are optimized for parallel resonance with the oscillator. If you use a crystal with serial cut (which can mostly be found in radio modules), the PIC won’t run with the correct frequency. For the PIC to run correctly at 40 MHz, a 10 MHz crystal is required, otherwise the MIDI baudrate will be wrong. Unfortunately every distributor has its own way of identifying the crystal type. If the crystal type is not specified, it’s most likely a parallel cut crystal.
The physical size of the faders is not important. The pots/faders should have 10k resistance. It’s important that they are linear, as opposed to logarithmic ones. The pots/faders in stereo equipment are almost always logarithmic, so you can’t take one from your dad’s stereo.
Trying to save money on wobbly cheap plastic faders, uh? You might hate yourself for that decision after six months of using your favorite new midi-toy. Consider that.
Yes, 1N4004 is a replacement for 1N4002, it’s just a type for higher Voltages (100V for 1N4002 vs. 400V for 1N4004). Any 1N400X diode will work in place of any other 1N400X diode -WITH A SMALLER NUMBER- Do replace a 1N4002 with a 1N4004 Don’t replace a 1N4004 with a 1N4002
Even though the MidiBox platform is 5volts, you’ll actually need a higher-volt rated power supply to get things working. Many seem to feel like a 9v dc power supply is a good choice for general MB use. Others seem to go a bit higher (as high as 12v) when powering the “instrument” type midiboxes like the sequencer or synths.
The PSU must be able to deliver constant power in milliamps above your total power consumption for the boards, pots, LEDs, etc. Buy more mA than you need, as the system will only draw what it requires. 500mA is the realistic minimum, but I personally have a 1.67amp 9v supply for my MB64e and it works great.
The more current your power supply can provide [measured in milliamps (mA) or amps (A)], the cooler it will run, and the better it will be able to respond to transient demands of your circuit.
Generally, buying a simple wall-wart external psu is the quickest and safest method to get your MB powered up. You might have a suitable PSU just lying around the house, but if not it shouldn’t cost more than 5-10 dollars from a decent electronic store.