Free Circuit Diagram

Using VFC110 chip, we can build a high frequency voltage-to-frequency converter. The features of this chip include the capability of high frequency operation, disable function, and an on-board precision 5V reference. This precision reference can be used to provide reference for offsetting the VFC transfer function, as well as provide transducer or bridge excitation. As [...]

The simple low-pass filter is shown in Figure below. The filter has a 20dB/decade roll-off after its corner frequency fc. Its low-pass frequency gain (f->0) is defined by R3/R1. This allows low-frequency gains other than unity to be obtained.  R2 should be chosen equal to the parallel combination of R1 and R3 to minimize error [...]

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, [...]

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 [...]

For the best advantage as a low noise high input impedance device, the preamp and tone control uses JFET. If the circuit reaches harmonic distortion levels of less than 0.05% with a S/N ratio of over 85 dB, all device parameters are non-critical. 18 dB of cut and boost is allowed by the tone controls. [...]

Using LM231/331 chip, we can build a low-cost voltage-to-frequency converter, ideal for analog-to-digital conversion, frequency-to-voltage conversion, long-term integration, linear frequency modulation-demodulation, and many other functions.  When it’s used as voltage-to-frequency converter, the output will be a pulse train with frequency linearly equal to the applied input voltage. For higher level of accuracy against temperature drift, [...]