I am being badgerd by my 15 year old to augment his audio rack with more DI boxes…
Does anyone have a Decent design they know of, preferably using cheap components…
I have this one http://www.muzines.co.uk/articles/direct-inject-box/2599 which should be relatively easy to replicate but it’s not passive… I found a design for a passive but the transformer was £60 lol…
Don’t mind converting a schematic to PCB… ( should tell him to learn!! )
Anything wrong with the one you linked to? I can help assemble the BOM for that if you like?
You need passive as in unpowered? I like that schem you posted I’m gonna save it! Would be real easy to have pcb made
Beyond it being from April 1981? 
Circuit is simple enough, though, but I suspect you could replace the LF353 with a TL072 that might be easier to source. On the other hand, LF353 is apparently still being made.
EDIT: Seems Tayda has the LF353, so probably not that hard to source. But I still suspect a TL072 might work just fine here (lower noise, less distortion, a bit lower typical bandwidth).
…
PS: They’re promoting Ultravox’ Vienna on the cover, a song that famously uses a CR-78 drum machine, but also has several precise tempo changes, something that caused certain challenges for the drummer when playing it live, since the CR-78’s tempo control was very much analog…
I have not tried it but was just wondering if anybody had a trusted known one up their sleeve…
I will draw it out in KICAD which will give me a BOM 
Cheers
Rob
@CTorp… I don’t need it, but my son does rightly point out that passive = no power = less to go wrong…
@fredrik… Yeah, in this simple analog world not much has changed so I am not concerned about it being 30 years old. I had already looked at the compatability of the T072 and it should be fine, the only difference in reality is it can’t handle the same level of bandwidth as the LF…
Will crack on over the weekend.
Cheers
Rob
schematic is all but done in KiCad…
probably have it finished off with the PCB over the weekend.
