∥
Components
Hit a Target
Series total
320 kΩ
Parallel total
68.8 kΩ
Add in parallel to R1
213 kΩ
to reach 68 kΩ
Add in series to R1
n/a
to reach 68 kΩ
Engineering Notes
How it works
Resistors and capacitors combine in opposite ways:
Resistors: R_series = R₁ + R₂ + … 1/R_parallel = 1/R₁ + 1/R₂ + …
Capacitors: C_parallel = C₁ + C₂ + … 1/C_series = 1/C₁ + 1/C₂ + …
In valve work, series capacitors are common in power supplies: two 450 V electrolytics in series give a 900 V-rated bank at half the capacitance. Parallel resistors are the standard trick for building odd values or spreading dissipation: two 2 W 10 kΩ resistors in parallel make a 4 W 5 kΩ.
The "hit a target" readouts tell you what to add to component 1 to reach any desired value, ideal for trimming a bias resistor or making up a non-standard tone-stack value.