Typically you get 2-3pF/inch of twisted wire that way.Make a gimmick capacitor by twisting two pieces of ordinary hookup wire.
Length mattersTypically you get 2-3pF/inch of twisted wire that way.
As does using insulated wire.Length matters
won't that make a mini inductor?Make a gimmick capacitor by twisting two pieces of ordinary hookup wire.
No, because the wires are not connected together. There is a very large resistance between the wires, just like a capacitor.won't that make a mini inductor?
No. You use two separate pieces of insulated wire twisted together. No connection between them. It's a simple two-plate capacitor with the wires being the plates.won't that make a mini inductor?
We've given you the info. I suggest you give it a try and let us know if it works. You shorten it and change the twist to tweak the value. Start with a longer wire then you think you need and keep snipping off a short piece of the ends until you get the right value.Thank for responding guys. I need the 5 pf trimmer to offset the vfo of my QRP cw transceiver about 1 kHz below the transmit frequency on receive, I wonder if the twisted hookup wire will do the job?
Few weeks ago I did that with a pair of tightly twisted wires.We've given you the info. I suggest you give it a try and let us know if it works. You shorten it and change the twist to tweak the value. Start with a longer wire then you think you need and keep snipping off a short piece of the ends until you get the right value.
Degradation of the insulation; although that may take several years.I wonder how stable the actual value could be. Besides temperature, what else could ruin the value?
Unfortunately, the OP doesn't know exactly what value he needs but is likely somewhere near 5pF and the wants to adjust/ tune his circuit. The lowest value is 3.5pF and, after soldering, may be outside the range the OP needs. The twisted pair method can be used for very fine tuning. Wires with varying thickness insulation can be used for varying degrees of control.I personally think it would be easier to buy one
Fair do's, the link I posted though had ones down to 1.5pFUnfortunately, the OP doesn't know exactly what value he needs but is likely somewhere near 5pF and the wants to adjust/ tune his circuit. The lowest value is 3.5pF and, after soldering, may be outside the range the OP needs. The twisted pair method can be used for very fine tuning. Wires with varying thickness insulation can be used for varying degrees of control.
by Jake Hertz
by Jake Hertz
by Duane Benson