10-27-2026, 12:25 AM
Hi Guys
In post-13 Resistor001 said he had trouble finding a specific cap value. This is pretty common.
When you cannot find a cap value you need, remember that capacitors in parallel add together. So, 270pF could be a 120pF and 150pF in parallel, or two 100pFs and a 68pF. This is okay if there is space - could be tricky on a tight PCB.
You could also tie caps in series to reduce the value. Two identical caps in series reduce to half the value. If the caps are dissimilar, then you use the series cap equation of the reciprocal of the sum of reciprocals. Personally, I prefer to parallel values when building towards a desired cap value.
Resistor values are easier for most hobbyists to make up. Values add in series and divide in parallel. The latter is again the reciprocal of the sum of reciprocals - easy with a scientific calculator.
In post-13 Resistor001 said he had trouble finding a specific cap value. This is pretty common.
When you cannot find a cap value you need, remember that capacitors in parallel add together. So, 270pF could be a 120pF and 150pF in parallel, or two 100pFs and a 68pF. This is okay if there is space - could be tricky on a tight PCB.
You could also tie caps in series to reduce the value. Two identical caps in series reduce to half the value. If the caps are dissimilar, then you use the series cap equation of the reciprocal of the sum of reciprocals. Personally, I prefer to parallel values when building towards a desired cap value.
Resistor values are easier for most hobbyists to make up. Values add in series and divide in parallel. The latter is again the reciprocal of the sum of reciprocals - easy with a scientific calculator.


