add Quad VCA page

_pages/modules.md

@@ -61,6 +61,12 @@ Following the links below will take you to the module details. Pay attention to
     - All you need in an ADSR
     - Switch to have 2 different time constants for the ADSR
 
+## VCAs
+
+- :warning: [Quad VCA](/quad_vca/)
+    - Quad VCA module, original design taken from Ray Wilson from [MFOS](https://musicfromouterspace.com/index.php?MAINTAB=SYNTHDIY&VPW=1697&VPH=669)
+        - Log/Linear response
+
 ## Power delivery
 
 -  :heavy_check_mark:  [Distribution board](/distribution_b/)

_pages/quad_vca.md

@@ -0,0 +1,75 @@
+---
+permalink: /quad_vca/
+layout: single
+title: "Quad VCA"
+category: "VCA"
+toc: true
+toc_label: "ToC"
+toc_icon: "cog"
+header:
+  overlay_color: "#5e616c"
+  overlay_image: /assets/images/Basic_VCA-top.png
+---
+
+![Quad VCA](/assets/images/Basic_VCA-top.png)
+
+:warning: **WIP WIP WIP WIP WIP** :warning: 
+
+Quad VCA module, original design taken from Ray Wilson from [MFOS](https://musicfromouterspace.com/index.php?MAINTAB=SYNTHDIY&VPW=1697&VPH=669)
+
+Possibility to have log and linear response for each VCA via a toggle switch. 
+
+CV inputs are normalled for channel 1-2 and channel 3-4, to have a stereo VCA with one CV signal. 
+
+All outputs are normalled to one another, to use the VCA as an active audio mixer. 
+
+## Schematics
+
+![Quad VCA schematic](/assets/images/Basic_VCA--Schematic.svg)
+![Quad VCA schematic](/assets/images/Basic_VCA-VCA_2.svg)
+
+All 4 channels of the VCA are a repeat of this schematic. 
+
+## BoM
+
+[See bom](/assets/bom/Basic_VCA_V1.0--iBoM.html)
+
+You can donwload the bom in excel format [here](https://github.com/BleepSound/basic_vca/releases/download/v1.0/Basic_VCA_V1.0--BoM.xlsx)
+
+
+## Build Informations
+
+Uses an SMD LM13700 because the DIP ones are not produced anymore (and expensive).
+
+Regular build, I use ceramic capacitors but you can use film/polyester.
+
+Polyester capacitor for the saw core. 
+
+:warning: When building modules, always do it in this order (from smallest component to highest):
+- diodes
+- resistors
+- DIP chips
+- capacitors (film/ceramic)
+- Transistors
+- Electrolytic capacitors
+
+To solder the headers, place them and place both PCBs in their final position before fully soldering the pin headers/sockets.
+
+For the next parts, always place them without soldering them on: 
+- jacks, pots and switches that go throught the front panel
+
+Once placed, put the front panel in place, then fasten all components to it. Once this is done, you can solder all the remaining components.
+
+## Images
+
+![3D Quad VCA(front)](/assets/images/Basic_VCA-3D_top.png)
+
+![3D Quad VCA(back)](/assets/images/Basic_VCA-3D_bottom.png)
+
+![3D Quad VCA(iso)](/assets/images/Basic_VCA-3D_top30deg.png)
+
+## Download
+
+Follow this link if you want to dowload the latest version of gerber files, schematic, kicad files...
+
+:arrow_down: [**Download**](https://github.com/BleepSound/basic_vca/releases)