Polystyrene

Polystyrene capacitors are film capacitors with excellent temperature stability. They  are low-loss, capacitors and have good high-frequency properties, and are commonly used in filters, timing circuits such as RF oscillators, and test instruments. The tolerance is normally ±5% or better - 1% is not uncommon. Polystyrene capacitors are unpolarised.

Due to the material in the capacitor, polystyrene capacitors are very sensitive to high temperatures. Care must be taken to avoid heating of the capacitor body during soldering – a combination of low temperature and short heating time is to be recommended. It is also helpful to keep the capacitor legs as long as is feasible (while avoiding potential short circuits), so that the heat from the solder joint has a longer way to travel before reaching the body. Another option is to dissipate heat away from the body by for example, pinching a large crocodile clip onto the leads between the solder joint and the capacitor body.

Polystyrene capacitors are typically manufactured in relatively low capacitances, from 1 pF to about 10 nF. As they can withstand relatively high voltages, they commonly have a rating of at least 50 V - usually more. 160 V is a common value. The operating temperature is typically -40 to +85 °C.

Polystyrene capacitors are occasionally called styroflex capacitors.