Can i sub normal capacitors for a variable cap to make an FM transmitter, or do i need that variable cap?
im trying to build a small fm transmitter, and i need a variable capacitor, but i dont have one. can i use regular caps in parallel in place of that variable cap?
For a receiver, since there are many stations, you need a variable cap to change frequencies. But for a transmitter, you definitely want a fixed cap since you want it to stay on the one frequency.
I would think it would work. you just need a starting point and your adjustment will be slower and probably less accurate.
Yes, you can. It will be helpful if you have an “assortment” of caps. All caps have a tolerance. So, with an assortment of same value caps, you can try different ones to help drop you on the frequency you are targeting, as each one’s value will likely be slightly different enough to alter frequencies.
Also, if you have one cap that places the transmitter frequency at the High-end of the band, then it is possible to “trim” the frequency down by parallelling the main cap with extremely small value caps. These “very small” value caps will increase the main cap value to cause lowering of the frequency…. but will take some trial and error.
You can accomplish a similar effect by cutting the cap leads length on the “long” side. Just by moving the position of the caps will cause its capacitance to vary just enough to “fine tune” its frequency.