An open, through-hole version of a board that was only ever sold. Its author had already modded a UD2.7C to pulse-skip and wanted the other half of what the commercial UD+ does: “proper current sharing through all the freewheeling diodes”, reached “by disabling half the bridge in an alternating fashion rather than just inverting one half”. Everything is TTL and through-hole by choice. The file is called UD+ THT. A TL3116 squares the feedback, with an adjustable phase-lead network on the input (RV2 against a 10 µH inductor). An LM311 handles overcurrent, with a selector that picks between an internal trip, a ramped one and an external input. An MC34164 holds reset. A chain of 74LS32, 74LS08 and 74HC74 generates the four alternating drive phases (with jumpers to swap phase on each output pair) into two UCC27423P drivers and IRF9540N/IRF540N totem poles feeding two gate-drive transformers. The schematic is complete and fully annotated. No board has been built or photographed yet.
Schematics and photos
schematic: “UD+ THT” (KiCad 9, A3)
Sources
This is the card from the driver tree, written from what the builder published. Send corrections through the forum.