Application of electrolytic capacitors in measuring circuits

Conclusions

Mass-produced electrolytic, and above all tantalum capacitors approach paper capacitors in many of their characteristics, and are superior to them with respect to their specific charges. In the range of −5 to +50‡C the electrolytic capacitors' values vary almost linearly with temperature. Moreover, capacitors designed for higher working voltages have a minimum instability. Aluminum capacitors type éM have the maximum instability, amounting approximately to 5–10% per 10‡C. Capacitors in hermetically-sealed casings types KéG and éGTs, groups OM and PM are 2–3 times more stable than the éM capacitors. Tantalum electrolytic capacitors have a stability 5–10 or more times greater than that of the éM capacitors.

The storage of éM capacitors at room temperature for 10,000 h changes their values by 6% towards the end of that time. Aluminum capacitors in hermetically-sealed casings after 2000–4000 h of preliminary storage provide a more stable capacitance, and tantalum capacitors then obtain virtually constant values.

It is possible to arrive at the conclusion from the measurement results that electrolytic capacitors, and above all tantalum capacitors, can be used successfully, in many instances, in various measuring circuits. Preliminarytesting and selection of capacitors, as well as the application of thermal compensating elements in measuring circuits with electrolytic capacitors will provide a higher precision of measurements.