This a modified TTSH SYNC PCB, to sync your 3 VCOs
my PCB version is improved and gives you Mounting holes, more space for MTA100 headers.
Buildguide:
https://www.dsl-man.de/display/TTSH/TTSH+Mod++VCO+Sync+Option
for all VERSION 2 owners: the resistor part numbers do not match with the schematic, use for the assembly the product picture or check the picture from my website.