Free Circuit Diagram

This audio frequency meter uses 555 IC as a monostable multivibrator (one-shoot trigger). A monostable multivibrator can act as a frequency-to-voltage converter because it produce a fixed pulse width, with the repetition rate/density is proportional to the triggering input frequency. Here is the circuit’s schematic diagram:

For resistor R1, because it set the measurement range, it’s [...]

Voltage to frequency is very useful in many situation, such as transmitting temperature measurement using standard voice radio transceiver. This circuit (see the circuit’s schematic diagram) uses only two CA3130 op-amps, but the performance is good enough. The linearity of the voltage-frequency transfer is better than 0.5% and the temperature coefficient is lower [...]

Frequency meter can be used in speed sensor, tachometer, or any measurement of repetitive signals. This frequency to voltage converter (FVC) can be used to turn your analog or digital voltmeter into a tachometer. The circuit’s schematic diagram is shown below.

The circuit consist of three blocks. The first block is a squarer, change the input [...]