Update 'Future Modules'

Future-Modules.md

@@ -6,24 +6,40 @@ What we build next?
 * Breadboard MK's 5-note sequencer.
 * Compare to online 8-note sequencers (baby 8)
 * Either build online 8-note schematic, or extend MK's 5-note to 8-note.
-
+* padding MK's out to 8 notes means roughly $16-20 in parts, depending on PCB choice
 # VCF
 #### MK's Diode Ladder VCF
+* ~$8 in parts, two tl074 op amps and otherwise a bunch of diodes and support
+
+# VCA
+#### MK's VCA
+
+* Probably a straightforward build, one op-amp, four transistors and some supporting components.
+* ~$6 in parts, needing only one 74 and support components, so tiny PCB should be fine
+
+# Sample & Hold
+#### MK's S&H, though maybe move the noise generator to a separate module?  If possible?
+* full unit is ~$8.50 - $10 in parts, mostly down to PCB for holding three chips (two 74s, one 72)
 
 # Noise
 #### MK's S&H
 
-* not strictly a noise generator, but contains one?
+* not strictly a noise generator, but contains one? see above
 
 #### MK's three-color noise generator
 
 * breadboard it
 * spectrum analysis
 * add more colors, if possible?
+* more details TBD
 
-# VCA
-#### MK's VCA
 
-Probably a straightforward build, one op-amp, four transistors and some supporting components.
+# Envelope Generator
+#### MK's A(d)SR
+* breadboard it at least, to understand it
+* decide if having D + R tied is a dealbreaker
+
+#### 7555-based ["Fastest Envelope In The West"](https://www.schmitzbits.de/adsr.html) (bottom one)
+* third iteration of a simple manual EG
+* ~$7 in parts, depending mainly on whether 8+6 pins + hardware fits on shaek board or similar size perf.
 
-#