Accurate 50Hz Oscillator Circuit Using 555 And 7490

Accurate 50Hz Oscillator Using 555 And 7490




Accurate 50Hz Oscillator Circuit Using 555 And 7490

This circuit is a getting a 50Hz pulse. It comprises a 555 timer and two 7490 divide-by-ten counter chips 7490.

Accurate 50Hz Oscillator Circuit Using 555 And 7490 IC 50 Hz

PARTS LIST
R1 2.2kΩ
R2 142kΩ (120kΩ + 22kΩ)
R3 5kΩ PRESET
C1 0.001µF (102)
IC1 NE555
IC2 7490 (SN74LS90N)
IC3 7490 (SN74LS90N)
IC4 7805 Regulator

The 555 generates a frequency of almost 5KHz which can be adjusted by VR1. This pulse fed to one divide-by-ten counter IC2 (7490) which gives an output of 500Hz (500KHz/10=500Hz). This frequency of 500Hz is again fed to the next counter IC3 to get 50Hz pulse (5ooHz/10=50Hz).

7490 SN7490A SN74LS90 SN74LS90N 7490N BINARY COUNTER IC 7490 SN74LS90N 7490N BINARY COUNTER IC pin configuration

To get accurate 50Hz pulse, the 5k preset has to be set.

The circuit works on a regulated supply of 5V.

If you reducing R2  (like 120kΩ), this circuit uses as 60Hz oscillator.

50Hz Oscillator TEST Circuit testing 555 oscillator output 50Hz Oscillator testing




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