I recently put together several Befaco kits (Rampage, Muxlicer, Burst, A*B+C) and I was really impressed with how well thought out the kits are. I would definitely recommend them as maybe not a first project but a good third or fourth.
Yes! I put the A*B+C kit together and it was really well done.
side note, it’s a super useful little utility module friend!
Further question on the manual gate. If I wanted it to send a fixed 5v signal, what’s a more sensible option: take power straight from the 5v rail on my bus board, or take power from the 12v rail and calculate a pull-down resistor?*
*if option 2, how does one calculate that?
If tapping from 12V, i would check a 7805 (or 7085, cant recall) regulator
Great, thanks! If I was using multiple manual gates, would I need one regulator for each gate?
I just built Robaux SWT16. It was a pretty easy build. All the components are through hole. The board I layer out well, the components are close but not crowded. I’d recommend this as a first build for anyone.
I just started Befaco HexVCA. This more difficult it has many more parts. It is still all through hole stuff. I’d say it’s beginner to intermediate. Not hard to do the assembly but will take some discipline to make.
When you say fixed 5V: how precisely? Exactly 5V to several decimal places? About 5V?
“about 5V” is straightforward. I am not always convinced you can rely on a 5V rail (not all power supplies emit them), but a 7805 regulator plus a pair of ceramic caps around it and a single impedence resistor going out would be very straightforward:
where ‘input’ is 12V, and ‘output’ should go to a 1k resistor and then out. I have been known to use 2 100n caps. But that’s the easiest way to derive 5V from 12V.
For reference, calculating a voltage divider - in the circuit depicted there, Vout = Vin * (R2 / (R1+R2)). I wouldn’t use that, though, I’d just use a 7805.
For multiple gates: yes, you can just use the same 5V line for all of them. Like so:
I mean personally I think it went too technical too fast but I hope it helped a little.
Thanks! this is really helpful. I got stuck into thinking that the voltage regulator went at the end of the circuit. D’oh!
I mean, there’s no real intuitive correct answer, so that’s easily forgiven!
The word ‘rail’ is often used with respect to power, and I think it’s a useful way to think of things: what voltages do I want on-demand, everywhere? So in Eurorack, that might be +/-12V, as our range for powering things like operational amplifiers. We might also want a 5V or 3.3V supply for microcontrollers, or perhaps as a gate standard. And then everywhere we want that, we can just tap that rail - and those are the sort of things we used fixed regulators for. By contrast, if there’s a single place a single thing is required - as part of a circuit - that’s where you might see voltage division.
(If you need a highly precise voltage, ie, to several dp of precision, that’s where ‘precision voltage sources’ come in handy - you’ll see these in ‘precision adders’, which are useful for interacting with V/Oct signals).
All useful info
My plan is to have simple more-or-less 5V sources as simple manual gates, mostly for vanilla things like progressing a sequential switch or triggering a S&H. Vaguely considering getting a few PCBs made that I can purpose for 1u Intellijel panels or 4hp or so 3u modules for different cases.
I found this post on adding mute switches to a Doepfer A-138, but I can’t work out from the image where the cables are going. Any ideas? Maybe they’re going to some resistors?
hmm, i would imagine you would want to break the circuit somewhere between the input and where the mixing occurs and then insert your switch. it’s hard to tell where on the board they are doing that (i disagree with the blog author’s statement that “The pictures are quite clear, so re-creating this mod will be a piece of cake…”). the best place might be to shove your switch in the circuit at the output of the input jack, depending on how doepfer connects their jacks to the pcb.
nearly done with the fifth of eight voice boards on my deckard’s dream build and i’m already gas’ing for my next project, lol.
Ha, yes I thought I was missing something when I read that! I’ll have a.look at the board and see what’s going on. Cheers!
post a couple pictures if you want! i’m curious.
Can anyone provide a link on octopart or otherwise to the spacers and screws that are used between PCBs, e.g. on the Turing Machine mkII? Compared to hunting down resistors and caps and the like, this is surprisingly difficult! All I know is that it should be 11mm long.