I searched available parts online — but there really aren’t any continuous mechanical variable capacitors around ~10 µF on Amazon, eBay, or typical component suppliers. Mechanical variable capacitors (rotary types) normally only go up to tens or maybe hundreds of picofarads, not microfarads. That’s because to make a true variable capacitor with capacitances in the µF range, you’d need extremely large overlapping plates or very small gaps — impractically large for a simple component.
🎯 Summary: No Practical 10 µF Adjustable Capacitor Available Off-The-Shelf
All of the variable capacitors you’ll find online — including small tuning caps or trimmers — are in the pF to low nF range, not µF:
- Typical variable / trimmer caps: ~~10 pF to ~120 pF or similar, tiny values mostly for RF tuning.
- Mechanical switching capacitor banks with rotary plates are also usually in the pF range.
There simply aren’t any standard mechanical variable caps at 10 µF because of physical size limitations — nobody makes them as standard products.
⚡ What You Can Do Instead
Since a true 10 µF variable doesn’t exist as a standard part, here are practical alternatives:
🔹 1. Use a Capacitor Bank/Decade Box
A decade box lets you switch different fixed capacitors in and out to vary the total. That gives you variable capacitance up to tens of µF.
Advantages:
- Precise control
- Easy to use for tuning
- Small size compared to mechanical variable
🔹 2. Use an Electronic Variable Capacitance (Varicap/Varactor)
These are tiny diodes whose capacitance varies with bias voltage.
But:
Standard varactors only reach tens to a few hundred pF, not microfarads — so they won’t replace a 10 µF load capacitor directly.
🧪 Build Your Own Adjustment
Since there’s no off-the-shelf 10 µF variable cap:
Option A: Parallel Fixed + Small Trimmer
Use a large fixed film cap (e.g., 8 µF) in parallel with a much smaller adjustable capacitor (or combination of smaller film caps and a small trimmer). This gives coarse + fine adjustment.
💡 Fixed Capacitors You Can Buy
If you just need fixed 10 µF caps to build your network or decade solution, these are easy to get:
Common 10 µF Capacitors
- – ~£6 — useful for experiments.
- – ~£2 — inexpensive general cap.
- – ~£5 — general purpose.
- – ~£7 — leaded electrolytic.
- – ~£6 — better quality film type for RF.
- – ~£8 — similar run capacitor.
These are fixed capacitors — but they give you the bulk bulk capacitance you need, and you can add smaller fixed caps in parallel (e.g., 1 µF, 0.1 µF etc.) to adjust overall value.
🧠 Best Practical Ways to Get Variable µF-Range
Because true mechanical variable µF capacitors don’t exist:
✔ Build your own using a decade box
Use a selector switch and multiple fixed caps to dial in the value you want.
✔ Use adjustable bank of fixed caps
Switch in/out combinations for tuning without expensive parts.
✔ Add a smaller parallel adjustable section
Like a small film trimmer or bank of switchable small caps — fine-tuning only.
🧩 Summary
❌ Amazon/eBay do not stock continuously adjustable 10 µF mechanical capacitors — the physical size makes them impractical.
✅ Fixed 10 µF capacitors are easy to get and inexpensive.
✅ For tuning, use small trimmers or a capacitor bank to give adjustable total capacitance.
A capacitor decade/selector box that lets you vary your effective capacitance up to ~20 µF with fine steps is a solid practical way to tune your loop at VLF.