rob's changes 005

basic_concepts/index.html

@@ -227,17 +227,17 @@ A good starting point for newcomers in the electronics field looking for what is
 
 
   ### Capacitors
-  - basic concept
+  - ####basic concept
 
   ![CPC](imgs-filippos/18-CPCs.JPG)
 
-  - Capacitance: the ratio of charge on one of the plates of a capacitor to the voltage that exists between the plates
+  - ####Capacitance: the ratio of charge on one of the plates of a capacitor to the voltage that exists between the plates
   C = Q/V, Units: Farads, 1F = 1C/1V
 
   ![CPC](imgs-filippos/19-CPCs.JPG)
 
 
-  - we could content with this limited knowledge. However, if you want
+  - we could be content with this limited knowledge. However, if you want
     - to build your own capacitors
     - understand time-dependent behavior such as displacement current and capacitive reactance
   - a deeper understanding of capacitance is needed:
@@ -247,25 +247,33 @@ A good starting point for newcomers in the electronics field looking for what is
   - A very nice Sparkfun tutorial on capacitors and their applicaitons:
   https://learn.sparkfun.com/tutorials/capacitors/introduction
 
-  - RC time constant.  Time domain behavior.
+  - ####RC time constant.  Time domain behavior.
 
   ![CPC](imgs-filippos/21-CPCs.JPG)
 
 
-  - Alternating Current in a Capacitor
-    - everything that is discussed about capacitors in dc circuits also applies in AC circuits with one major EXCEPTION
-    - DC circuit:
-      - block current flow (except during short time of charging and discharging)
-    - AC circuit:
-      - pass or limit current flow depending on frequency
-    - capacitor; stores electrical energy and returns it ot the circuit
 
+  - ####Capacitors in filters:  low pass and high pass.
+The charging and discharging of the RC combination makes capacitors useful as frequency filters.
 
-  - low pass (PWM to make analog out)
-  - high pass (coupling audio signals)
-  - filter capacitors on power rails.
-  - using capacitors as sensors
+  ![CPC](imgs-filippos/lp_hp.jpg)
 
+---
+
+  - ####filter capacitors on power rails.
+Capacitors resist changes in voltage by virtue of their energy-storage capabilities.
+We use them to absorb fluctuations in power supply voltage in almost every board that we make.
+  ![CPC](imgs-filippos/Supply_filter_caps.png)
+
+  ---
+
+  - ####using capacitors as sensors
+  Capacitance sensing is used in many ways.  During our "Input devices" week, you will see practical examples of this.
+
+  ![CPC](imgs-filippos/cap_loading.jpg)
+  ![CPC](imgs-filippos/cap_txrx.jpg)
+
+---
 
   ### Transistors
 
@@ -315,6 +323,19 @@ A good starting point for newcomers in the electronics field looking for what is
   - A nice tutorial on BJTs from Sparkfun:
   https://learn.sparkfun.com/tutorials/transistors#applications-i-switches
 
+#### FETs
+
+- Field Effect Transistors.  [Article](https://www.electronics-notes.com/articles/electronic_components/fet-field-effect-transistor/what-is-a-fet-types-overview.php)
+A small voltage on the input, requiring essentially no current, controls a large current through the transistor.
+
+- Below are two of the FETs in the fab inventory.  Both n-type MOSFETS.  Left 1.7 amps, right 16 amps max. current.  We also have p-type MOSFETS.
+
+
+  ![CPC](imgs-filippos/mosfets.jpg)
+  ![CPC](imgs-filippos/nmosfet.jpg)
+
+####Relays
+
   - Controlling high voltage power devices using transistors:
    https://www.instructables.com/id/Arduino-Tutorial-Handling-High-Power-Devices/