Hi everybody,
I was messing around with Fairchild 660/670 timing network lately and after doing some calculations it seems like there is a problem with the data in the manual regarding the release times. I could be wrong, I'm just curious what you guys think.
The original manual release times are:
Position 1: 0.3 Sec.
2: 0.8 Sec.
3: 2 Sec.
4: 5 Sec.
5: 2 Sec. for individual peaks
10 Sec. for multiple peaks
6: 0.3 Sec. for individual peaks
10 Sec. for multiple peaks
25 Sec. for consistently high program level
Time constant formula is T=R x C, where T is discharge time in Seconds, R is resistance in Ohms and C is capacitance in Farads.
Now, let's calculate release times for each position
Position 1:
2uF cap with 220K and 68K resistors in parallel.
Paralleled resistors will have resistance of 51.94K or ~50K.
T=50000 Ohms x 0.000002 F=0.1 Sec.(0.3 Sec. in the manual)
Position 2:
2uF cap with 220K and 470K resistors in parallel.
Paralleled resistors will have resistance of 149.85K or ~150K.
T=150000 Ohms x 0.000002 F=0.3 Sec.(0.8 Sec. in the manual)
Position 3:
2uF cap with 220K and another 2uF cap.
T=220000 Ohms x 0.000004 F=0.88 Sec. ~0.8 Sec.(2 Sec. in the manual)
Position 4:
2uF cap with 220K and another 2uF and 4uF caps.
T=220000 Ohms x 0.000008 F=1.76 Sec. ~2 Sec. (5 Sec. in the manual)
Position 5:
2uF cap with 220K and another 2uF for individual peaks.
T=220000 Ohms x 0.000004 F=0.88 Sec. ~0.8 Sec. (5 Sec. in the manual)
8uF and 100K and 220K resistors in series for multiple peaks.
T=320000 Ohms x 0.000008 F=2.56 Sec. (10 Sec. in the manual)
Position 6:
2uF with 220K for individual peaks.
T=220000 Ohms x 0.000002 F=0.44 Sec. (0.3 Sec. in the manual)
8uF and 100K and 220K resistors in series for multiple peaks.
T=320000 Ohms x 0.000008 F=2.56 Sec. (10 Sec. in the manual)
20uF and 100K and 220K resistors in series for consistently high program level.
T=320000 Ohms x 0.00002 F=6.4 Sec. (25 Sec. in the manual).
Positions 5 and 6 are more complicated, so I'm probably missing something there, but 1-4 are very basic and if you compare the original values with calculated ones, it seems like they somehow got shifted by one. Would love to hear your thoughts.
I was messing around with Fairchild 660/670 timing network lately and after doing some calculations it seems like there is a problem with the data in the manual regarding the release times. I could be wrong, I'm just curious what you guys think.
The original manual release times are:
Position 1: 0.3 Sec.
2: 0.8 Sec.
3: 2 Sec.
4: 5 Sec.
5: 2 Sec. for individual peaks
10 Sec. for multiple peaks
6: 0.3 Sec. for individual peaks
10 Sec. for multiple peaks
25 Sec. for consistently high program level
Time constant formula is T=R x C, where T is discharge time in Seconds, R is resistance in Ohms and C is capacitance in Farads.
Now, let's calculate release times for each position
Position 1:
2uF cap with 220K and 68K resistors in parallel.
Paralleled resistors will have resistance of 51.94K or ~50K.
T=50000 Ohms x 0.000002 F=0.1 Sec.(0.3 Sec. in the manual)
Position 2:
2uF cap with 220K and 470K resistors in parallel.
Paralleled resistors will have resistance of 149.85K or ~150K.
T=150000 Ohms x 0.000002 F=0.3 Sec.(0.8 Sec. in the manual)
Position 3:
2uF cap with 220K and another 2uF cap.
T=220000 Ohms x 0.000004 F=0.88 Sec. ~0.8 Sec.(2 Sec. in the manual)
Position 4:
2uF cap with 220K and another 2uF and 4uF caps.
T=220000 Ohms x 0.000008 F=1.76 Sec. ~2 Sec. (5 Sec. in the manual)
Position 5:
2uF cap with 220K and another 2uF for individual peaks.
T=220000 Ohms x 0.000004 F=0.88 Sec. ~0.8 Sec. (5 Sec. in the manual)
8uF and 100K and 220K resistors in series for multiple peaks.
T=320000 Ohms x 0.000008 F=2.56 Sec. (10 Sec. in the manual)
Position 6:
2uF with 220K for individual peaks.
T=220000 Ohms x 0.000002 F=0.44 Sec. (0.3 Sec. in the manual)
8uF and 100K and 220K resistors in series for multiple peaks.
T=320000 Ohms x 0.000008 F=2.56 Sec. (10 Sec. in the manual)
20uF and 100K and 220K resistors in series for consistently high program level.
T=320000 Ohms x 0.00002 F=6.4 Sec. (25 Sec. in the manual).
Positions 5 and 6 are more complicated, so I'm probably missing something there, but 1-4 are very basic and if you compare the original values with calculated ones, it seems like they somehow got shifted by one. Would love to hear your thoughts.