Capacitor conversion

[bobthebuilder]

For a school project my teacher ordered two 47 pf capacitors instead of one 47 and one 4.7. I was wondering if it was possible to convert one of the 47pf to a 4.7 pf by use of a resistor or something. Ordering the correct part would take forever because of my school so any help would be great.

 

[sardineta]

you can make an arregment of series capacitors, due to the electrical behavior is like a parallel in resistors (look for it in a circuit book).

resistors do not reduce the value of a capacitor.

 

[sardineta]

if you do it by hand, fix one capacitor (use commercial values) and discover the other one,

4.7pF= C1C2/(C1+C2)
C1=the value you wish
you can expand this to more capacitors, it is only mathematics

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capac.html#c1

 

[Styx]

no you cannot change the capacitance of a pre-packaged capacitor. if only you have 10 of these, you could have series 10 off to get 4.7

What is this capacitor being used as?
for that low it is probably part of a timing cct and thus there will be a resistor near it.

for the capacitance being 10x too big to get the same effect (if it is a RC cct) you will need 1/10 of the resistance

what is the circuit so qwe can see if that is possible or whether 47pF will do

 

[bobthebuilder]

Here is the diagram.

 

[Styx]

oh dear, that is part of a tuned cct - not an RC. The only thing you could do is if it is a custom choke, wind it with a factor of 10 less turns.

however, it looks like it is an only has 5 turns so oh dear, just get some 4.7pF

 

[zachtheterrible]

if you have two insulated wires, you can twist them together to make a capacitor. i'm not sure of the values that you can get. the only way that you'd be able to do this is to have a capacitance meter, otherwise, you'd have no idea what the value of your wire capacitor is.