Low frequency to DC voltage converter - has comparator for two integrators to avoid large number of filters

摘要

The circuit converts a variable frequency into a proportional DC voltage. A constant DC voltage is first integrated for a period corresponding to the variable frequency and the resulting value is stored. A second integrator (14) integrates a constant DC voltage at a second time constant and a comparator (13) compares its output with that of the main integrator (12). A switch (17) is provided which switches on for a specific time to the DC output terminals (19) when triggered by the comparator on agreement of its two inputs and at the same time resets the second integrator (14) to zero. This circuit reduces the total number of filters required.