Whether you’re a hobbyist tinkering in your garage or an engineer working on a commercial product, capacitance will be a critical factor as you look to design efficient, reliable, and cost-effective circuits.
Certainly, the task of choosing the right capacitor for any given job is likely to be a balancing act between ensuring the necessary performance and keeping costs low.
In the UK, for example, such factors as import costs, VAT, and market availability can all potentially exert upward pressure on costs. This makes it important to carefully manage how much you spend on these vital electronic components.
In this guide, then, we will take a closer look at the safe and practical ways to achieve the necessary capacitance for your given project or application, without straying beyond your budget.
What Is Capacitance, And Why Is It So Crucial?
Capacitance can be defined as the ability of an object – such as a circuit or component – to collect and store energy in the form of an electrical charge.
Although capacitance is measured in farads (F) – this unit forming part of the International System of Units (SI) – in practice, it is smaller units that tend to be used in projects. These encompass the likes of microfarads (µF), nanofarads (nF), and picofarads (pF).
Determining the right capacitance value for your circuit, and using the components that match this requirement, will be integral to your efforts to make sure the final product functions as intended.
It is also true, though, that capacitors come in a broad range of types, sizes, and tolerances, with the prices of these components varying significantly, too.
You won’t want to choose the wrong capacitor for your project or to over-specify, given that this would drive up costs. But nor will you want to risk under-specifying, as this could heighten the likelihood of circuit failure.
3 Ways to Achieve Your Required Capacitance Safely and Economically
Pursue these strategies to help ensure you make the best decisions when in need of capacitors, while keeping unit costs reasonable:
- Use Standard Capacitor Values
It is typical for capacitors to be produced in standard values, such as 10 µF, 22 µF, or 100 µF. These variants are widely available, with economies of scale helping to make them generally cheaper than non-standard values.
For example, it is generally more cost-effective to obtain a 100 µF capacitor from a reputable supplier such as RS, than it is to order a 95 µF capacitor, which may require special manufacturing.
- Combine Capacitors in Parallel or Series
It may be the case, of course, that your design requires a non-standard capacitance. In that case, you may consider combining standard capacitors in parallel or series as a means of approximating the value desired.
For instance, the use of two 47 µF capacitors in parallel would yield 94 µF, which may be good enough for a design requiring 95 µF. By taking this approach, you can help to avoid the higher pricing associated with bespoke components.
When it comes to combining capacitors in parallel – as can be useful for increasing capacitance – the total capacitance will be the sum of the individual capacitances.
If, on the other hand, you are seeking to reduce capacitance or to achieve precise values, you might think about having your project’s capacitors in series. With this arrangement, the total capacitance would be calculated as Ctotal = 1/C1 + 1/C2 + …
To ensure safety, don’t forget to check that the voltage ratings of the capacitors you use meet or exceed the requirements of the circuit.
- Buy In Bulk and Compare Suppliers
If you’re reading this as an engineer or hobbyist in the UK, you will likely be familiar with how VAT (20%) and potential import duties can push up the costs of electronics components.
Those additional expenses will sting if you’re constantly placing only small orders. So, if you can, it makes sense to buy in bulk, from suppliers – such as RS – that have a good industry reputation.
If your chosen sources have UK warehouses, this can further help to minimise shipping delays and costs.
The Role of a Capacitance Unit Conversion Calculator
When you are designing circuits or trying to find components, you will likely come across capacitance values expressed in various units. As we touched on earlier, these include such units as microfarads (µF), nanofarads (nF), or picofarads (pF).
Fortunately, it is easy to find a decent µF to nF to pF converter online that will enable you to quickly and accurately convert between these units, whenever you need to do so. This will be vital for ensuring component compatibility and avoiding errors.
Follow These Measures to Ensure Cost-effective Circuit Designs
It doesn’t have to be an impossible task to achieve the capacitance that your project requires at the same time as keeping unit costs reasonable.
It is, though, a process that will require you to know a few things about strategic component selection, and how you can leverage standard values and make savvy use of parallel or series configurations.
Pursue the aforementioned strategies at the same time as keeping a close eye on safety and reliability, and you will be well-placed to put together efficient and dependable circuits that don’t break the bank.
