add zener to protect ADC load cell input

[hw/quantimotor] / telestatic.sch

diff --git a/telestatic.sch b/telestatic.sch
index 39124fbd2126081b3934dfffda09b53e5fb485cf..7af5e2c1fc94cfb141f81ddffe97fc7f84d8801b 100644 (file)
--- a/telestatic.sch
+++ b/telestatic.sch
@@ -1,9 +1,9 @@
-v 20201211 2
+v 20211219 2
 C 40000 40000 0 0 0 title-E.sym
 N 54800 41700 65600 41700 4
 N 57300 41700 57300 43200 4
 C 41900 57800 1 0 1 gnd.sym
-T 79000 41900 9 30 1 0 0 0 1
+T 78800 41800 9 30 1 0 0 0 1
 TeleStatic
 C 44900 46200 1 0 0 gnd.sym
 N 42600 46700 41200 46700 4
@@ -55,7 +55,7 @@ netname=sense_batt
 }
 C 47500 41300 1 0 0 gnd.sym
 T 82400 40400 9 10 1 0 0 0 1
-4
+4.1
 T 80000 40400 9 10 1 0 0 0 1
 1
 T 80600 40400 9 10 1 0 0 0 1
@@ -1892,8 +1892,8 @@ T 44700 53500 5 10 1 1 180 6 1
 netname=adc_drdy
 }
 N 76600 72900 76300 72900 4
-T 77400 40600 9 10 1 0 0 0 3
-           Copyright 2020 by Bdale Garbee <bdale@gag.com>
+T 77100 40600 9 10 1 0 0 0 3
+           Copyright 2022 by Bdale Garbee <bdale@gag.com>
 Licensed under the TAPR Open Hardware License, http://tapr.org/OHL
 
 N 76600 65700 76500 65700 4
@@ -2088,7 +2088,7 @@ A 3mV/V load cell excited with 10V
 needs gain 167 to optimally drive 
 5V ADC input, which is 369 ohms.
 The next higher std value is 374.
-T 60600 68700 9 10 1 0 0 0 1
+T 60400 68700 9 10 1 0 0 0 1
 10V default
 T 60900 66100 9 10 1 0 0 0 9
 excite +
@@ -3031,3 +3031,20 @@ value=NoConnection
 T 55600 54700 5 10 0 0 0 0 1
 device=DRC_Directive
 }
+C 72500 69500 1 90 0 zener.sym
+{
+T 71900 69900 5 10 0 0 90 0 1
+device=DIODE
+T 72000 69700 5 10 1 1 0 6 1
+refdes=Z1
+T 72000 70000 5 10 1 1 0 6 1
+value=5.1V
+T 72500 69500 5 10 0 1 0 0 1
+footprint=0805diode
+}
+C 72200 69200 1 0 0 gnd.sym
+T 71400 68400 9 10 1 0 0 0 3
+Protect ADC input 
+should INA125 output 
+exceed 5V ADC range
+C 40800 57300 1 0 0 gnd.sym