I am moving Kerry's mini GRHV\GRLV GB discussion to its dedicated thread here. I also included JoaMat's mini T2 here to see if we have enough interest for a GB.
The table will be updated periodically as more people participate. Apologize if I missed someone or something - just let me know so I can correct the data.
I put down one set for those that have not decided on the number of sets they want.
The plan is to have assembled GRHVxxx boards, rest of boards will be PCB only.
See discussions on the PS in this thread. mini T2 build discussion in this thread.
Construction notes:
R3 and R2 determine the regulated voltage for GRLV. The formula is Vout = (R2 + R3)/R3 * Vref. Vref is the reference voltage of U4 (LT1021).
R7, R8, R9, R10 determine the regulated voltage for GRHV. The formula is Vout = ((R8 +R9 + R10)/R7 + 1) * Vref. Vref is the reference voltage of IC1 (LT1021). You want to keep R8, R9 R10 values close so they have even voltage drop across each of them.
On the PSU Main board, R22 (100K) and C17 (470uf) set up the delay time for HV. The 100k/470uf combination provides a roughly 45 seconds delay. Increase R22 or C17 to increase the delay time. C17 needs to be rated 5VDC or higher.
Board dimensions:
mini T2: 160mm x 100mm
GRHVxxx: 41mm x 31mm
GR78xx/GR79xx: 30mm x 20mm
Main board (PSU): 140mm x 90mm
See BOM for boards at the bottom.
Blank in the GRHVxxx-bare column indicates that the participant has not responded on this thread to indicate the preference for bare or partially-assembled boards and is deemed to opt for partially-assembled board by default as previously communicated.
BOM:
GRHV78xxx-BOM.xlsx
miniT2v.22_Date_2020-02-16.xls
GR78xx - V2 .xlsx
GRHVBase-BOM - V2 production.xlsx
GR79xx-V2.xlsx