yellow boards

#notes for rev.0 PCBs (= yellow PCBs):

• the main difference vs. rev.1 are:

  • the quad op amp is a TL074.

  • pin usage is different: pins 28 and 29 are used as clock outputs = you have to solder the pads that say 28 and 29 to the eponymous SMD pads on the bottom of the teensy (which is a bit of a nuisance, which is why i've changed that in the revised version).

  • you have to use a 79L05 (seven nine zero five) for the -5V offset (there's no LM4040-5V); that's the part right next to the 3 pin header labelled CV trim.

• the four sot-23 parts in vicinity of the teensy are bat54s (mouser # 78-BAT54S-G3-08), these protect the ADC from overvoltage; hence you want them there.

• ignore the parts labelled LM1432, AREF, and lm4040-3; they're not needed.

• jumper the 3v3 pad right above the LM1432 footprint; also jumper the pads labelled DAC/CLK and CV trim. (see main build guide)

• there's two diode footprint at the bottom of the board, near the jacks: use 33k resistors instead; or, if you have any, use a Schottky diode ('minimelf'); either will protect the transistors from too much V_ebo.

• other than that, you can follow the build guide for the later version. the only thing to keep in mind is that, when compiling the firmware, you have to comment out the lines that say #define _TEMPS_UTILE_REV (in temps_utile.ino and u8g_teensy_14.cpp or, if you want to try the dev firmware, in TU_gpio.h)

• here's a picture: