MOD1428#1: swap of feedback wires of tank circuit at P3-P4
MOD 1436#1: Be sure midpoint R12, R13 only have one connection: U4 pin 9 - done
MOD 1436#2: Be sure U7 pin 1 and 2 are connected (no connection on the diagram) pin 1 is put to GND, done
C12 = 1.1 nF
R14 = 5.7k
Set center frequency to 6240 hz
At VCO = 0V freq = 4875 hz
At VCO = VCC freq = 7280 hz
At 4875 hz phase of feedback signal advancing phase of oscillator signal
At 7280 hz phase of oscillator signal advancing phase of feedback signal
MOD 1446#1 Break connection between R12-R13 and U4 pin 9 - done
MOD 1446#2 Connect RV7 pin 1 to U4 pin 9 - done
MOD 1446#3 Connect one led to VCC having light on when connected to GND via a 10K resistor (test it), but the resistor is instead of GND connected to U4 pin 2 - done
MOD 1446#4 Connect one led to GND having light on when connected to VCC via a 10K resistor (test it), but the resistor is instead of VCC connected to U4 pin 2 - done
OBS1448#1:
At 4866 hz duty cycle of U4 pin 2 is 20% high
at 5695 hz the duty cycle of U4 pin 2 is 4% high
at 7248 hz the duty cycle of U4 pin 2 is once 7% and once 14%
MOD 1436#1: Be sure midpoint R12, R13 only have one connection: U4 pin 9 - done
MOD 1436#2: Be sure U7 pin 1 and 2 are connected (no connection on the diagram) pin 1 is put to GND, done
C12 = 1.1 nF
R14 = 5.7k
Set center frequency to 6240 hz
At VCO = 0V freq = 4875 hz
At VCO = VCC freq = 7280 hz
At 4875 hz phase of feedback signal advancing phase of oscillator signal
At 7280 hz phase of oscillator signal advancing phase of feedback signal
MOD 1446#1 Break connection between R12-R13 and U4 pin 9 - done
MOD 1446#2 Connect RV7 pin 1 to U4 pin 9 - done
MOD 1446#3 Connect one led to VCC having light on when connected to GND via a 10K resistor (test it), but the resistor is instead of GND connected to U4 pin 2 - done
MOD 1446#4 Connect one led to GND having light on when connected to VCC via a 10K resistor (test it), but the resistor is instead of VCC connected to U4 pin 2 - done
OBS1448#1:
At 4866 hz duty cycle of U4 pin 2 is 20% high
at 5695 hz the duty cycle of U4 pin 2 is 4% high
at 7248 hz the duty cycle of U4 pin 2 is once 7% and once 14%
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