r5B12 boards assembled

A project log for DIY programmable (SCPI) bench power supply

Bridging the gap between professional and DIY/hobbyist bench power supply

DenisDenis 03/11/2017 at 14:260 Comments

The new r5B12 PCBs arrived from ITEAD few days ago and I managed to assemble them to test if new added features are working as expected. All boards are now a little bit larger and I tried to keep the same mounting holes spacing as in previous builds.

AUX PS module
This module now has additional MCU controlled power relay with NO and NC pins exposed and reachable from the rear panel (X6 connector). Cooling fan power is now isolated, 5V buck is removed and dual output 5 W AC/DC module from Vigortronix is used instead.

Power board
It's possible now to work with two current range e.g. 0-500 mA and 0-5 A (on the picture that is down left corner section with Q13, Q14, R63, R65). Current shunt monitor op amp (IC7) is changed to LTC2050HV (see sheet #3). I also replaced bias power supply (see Sheet #2) where now TL781 and LTC3260 are used instead of buck regulator (LM5574).
I found two stupid mistakes on this PCB: the power input connector (X2) is rotated i.e. not the same as on the previous board, and choke L1 that is now smaller need different holes spacing.

Arduino shield

The most important changes here is encoder that can be now mounted directly on the PCB. Due to that TFT display is moved to the left. PE (Earth) terminal is moved below encoder.
I added 20-pin 0.5 mm FFC connector (X20) for future upgrade to Riverdi 3.5" touch screen display with FT800 (resistive) or FT801 (capacitive) controller. Since that display also has audio, a small audio amplifier is also added (TPA6205).
Playing with PCB layout I succeed to swap control lines for AC power (PWR_SSTART and PWR_DIRECT), but that is corrected and uploaded on the GitHub.

I need to test few more things and if everything is fine I can send to ITEAD final Gerbers and BOM to initiate PCB assembly of few sets first and after that to proceed with the rest that needed for crowdfunding campaign fulfillment.