diff --git a/Docs/build.md b/Docs/build.md index 7460bac..c4a636e 100644 --- a/Docs/build.md +++ b/Docs/build.md @@ -6,12 +6,18 @@ The build is pretty straightforward except for mechanical assembly, and one othe C10 and C11 are the capacitors that determine the envelope shape in conjunction with the four pots. The "Speed" switch selects whether C10 ("fast") or C11 ("slow") is used. 1 µF for C10 and 10 µF for C11 is suggested but you can try other values, smaller ones for faster timings and larger ones for slower. -In my tests, both aluminum electrolytic and tantalum caps caused the envelope's maximum to fall a little short of 8 V, and the sustain level to slope downwards with long gates. In both respects the tantalum did a little better, but not much. On the other hand a polyester film cap resulted in a maximum of 8 V and a flat sustain. Unfortunately 10 µF film caps are large and expensive, and ten 1 µF film caps in parallel would require an auxiliary board nearly as large as the main one. So my preference is a 1 µF film and a 10 µF tantalum. - If you want to experiment, you can. J6 is an optional SIP socket (you could use a pin socket, but a SIP socket works better) for socketing the capacitors. There are 7 positions. As indicated by the lines on the silkscreen graphtics, the C11 + leg (if polarized) can go in either of the leftmost two positions, the C11 - leg in either of the next two, the C10 + leg in either of the next two, and the C10 - leg in the last one. This accommodates various possibilities for cap lead spacing. When and if you decide on a pair of capacitors you can solder them into the C10 and C11 footprints above the SIP socket. ![](../Images/capsocket.png) +I tried one sample each of aluminum electrolytic and tantalum at 1 µF and 10 µF, as well as a PET film at 1 µF. Attack was set fairly fast, sustain at 100%, release as fast as possible. Interestingly, the tantalum was better (less sag over a 2.5 second sustain) than the aluminum at 1 µF, but at 10 µF the aluminum looked better while the tantalum was horrible: + +![](../Images/captest.png) + +I was sufficiently shocked by the 10 µF tanty to try two more (same type, from the same order). One looked about the same, the other was worse. + +The 1 µF film ruled, however; it was just about perfectly flat across the full sustain. Unfortunately 10 µF film caps are large and expensive, and ten 1 µF film caps in parallel would require an auxiliary board nearly as large as the main one. So my current preference is a 1 µF film and a 10 µF aluminum. Of course a sample of one of each type is not a lot to go on. + ## Mechanical assembly Regarding the board mounted potentiometers, there are two overlapping footprints provided for each, allowing you to use your choice of 9 mm or 16 mm vertical pots. You can even use a mix of the two, if you want. But see below for possible issues; I have tested only 16 mm. diff --git a/Images/IMG_6753.JPG b/Images/IMG_6753.JPG new file mode 100644 index 0000000..7e4d07e Binary files /dev/null and b/Images/IMG_6753.JPG differ diff --git a/Images/IMG_6770.JPG b/Images/IMG_6770.JPG new file mode 100644 index 0000000..a551bbc Binary files /dev/null and b/Images/IMG_6770.JPG differ diff --git a/Images/IMG_6771.JPG b/Images/IMG_6771.JPG new file mode 100644 index 0000000..7c13838 Binary files /dev/null and b/Images/IMG_6771.JPG differ diff --git a/Images/IMG_6777.JPG b/Images/IMG_6777.JPG new file mode 100644 index 0000000..cb0dac0 Binary files /dev/null and b/Images/IMG_6777.JPG differ diff --git a/Images/captest.png b/Images/captest.png new file mode 100644 index 0000000..a97ceb2 Binary files /dev/null and b/Images/captest.png differ diff --git a/README.md b/README.md index 0bc231f..a4e82f3 100644 --- a/README.md +++ b/README.md @@ -11,9 +11,16 @@ The present design adds the following features: * Retriggering input, allowing additional attack/decay peaks on top of the sustain. * Looping mode, allowing attack-decay envelopes to repeat as long as a gate is present, or, if nothing is plugged into the gate input, indefinitely. This can be used as a sequence of envelopes or as a kind of odd LFO. +## Known problems + +I’ve discovered looping stops if the decay time is turned up beyond some point, about 2/3 or a little less of the way up on the fast setting or maybe 20% of the way up on the slow setting (which is about the same decay time). The whole attack time range is available and the decay time limit doesn’t seem to depend on attack time. Sometimes it’ll go for 2 or 3 pulses before stopping. I have no idea why unless it has to do with the folly of using a TL071 as a comparator. + ## Photos -[to be added] +![](Images/IMG_6753.JPG) +![](Images/IMG_6770.JPG) +![](Images/IMG_6771.JPG) +![](Images/IMG_6777.JPG) ## Documentation: