Frequency to Voltage Converter Circuit using 555

Last Updated on March 16, 2024

Circuit which converts Frequency of input signal into a proportional Voltage output is known as Frequency to Voltage converters some times it termed as FVCs or F to V Converters. Frequency measurement is required in numerous applications like Liquid flow measurement, Tachometers and speed control, Light Intensity Measurement, Vibration Monitoring and Temperature measurement etc.., Here Frequency to Voltage Converter Circuit using 555 Timer designed to implement in such projects and applications.

Here IC 555 configured in Monostable Multivibrator mode and it produce output pulse depends on the input frequency level. Before this stage input signal frequency is converted into triggering spike signal by using Capacitor C5 and Diode D1. This triggering spike should be equal to 2/3 or 1/3 of VCC applied to the timer IC 555.

Circuit Diagram

Components Required For PCB (BOM)

1	C1, C2, C3, C4	0.01μF	C_Disc_D3.4mm_W2.1mm_P2.50mm	4
2	C5	47μF	CP_Radial_D5.0mm_P2.00mm	1
3	R2, R5	47KΩ	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	2
4	R1	100Ω/1W	R_Axial_DIN0309_L9.0mm_D3.2mm_P12.70mm_Horizontal	1
5	R3	10KΩ	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	1
6	R4	10Ω	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	1
7	R6	1KΩ	R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	1
8	D1	1N4148	D_DO-35_SOD27_P7.62mm_Horizontal	1
9	U1	NE555D	DIP-8_W7.62mm	1
10	Q1	2N2222	TO-92	1
11	J1	I/P Signal	PinHeader_1x02_P2.00mm_Vertical	1
12	J2	12V DC	PinHeader_1x02_P2.00mm_Vertical	1
13	J3	V.out	PinHeader_1x02_P2.00mm_Vertical	1

Construction & Working

Input signal either Square wave or Sine wave should be converted into triggering spike before reaching timer IC triggering pin then only we can oscillate mono pulse depends on the triggering signal. Output pulse duration is depends on the Timing Resistor R3 and Timing Capacitor C4. Output from the timer IC is connected to the Output pin headers J3 through R1 and C1. Here C1 Removes noise spike in output pulse (Voltage). Transistor Q1 is connected across the Timing Capacitor C4, Input signal is converted into triggering spike by using C5 and D1 elements and reaches base terminal of Q1. When the positive potential rises Q1 gets turn ON and Discharges C4 Capacitor. When the Negative potential rises Q1 gets turn OFF and gives time to C4 for charging. This cycle repeats depends on the input signal frequency.

By this way timer IC frequently triggered by input signal frequency and gives output Pulse (Potential difference – Voltage). Calibrate this circuit and tune components value depends on your need. If you are looking for a circuit which divides the input frequency and gives output. Following Schematic will help you.