Hi all,
I am building a ECG circuit, and I've read some discussions on this forum. I have a question: In a book on reducing noise, one says for low frequency we should use electrolytic capacitors and limit resistor values due to temp noise. We can use parallel and series grounding to minimize noise. Is it true? (on the forum the advice is that no electrolytic capacitors is used because of tolerance).
Different types of capacitors have different characteristics so they are used in different circuits. Electrolytic capacitors have a poor accuracy, high leakage and are polarised. But the have high values. So you would use them when you need a high value and don't mind about the other characteristics so much.
For filters, you usually want high accuracy and non-polarised so would pick a different type. In the past that might have been polypropylene or polyester but nowadays there are very good ceramic capacitors around, so they can be used.