Feature: Power


Powering the 555 timer from a supply with ripple


T


By Sulaiman Al-Gharbi, Managing Director, Smart PCB Solutions, Irbid, Jordan Figure 1: Circuits A and B


he 555 timer is widely used in many consumer electronic devices. It is designed to be powered by a stable DC power supply, yet sometimes it’s powered


by a poorly-regulated AC source. Here we discuss the deficiencies and performance of the 555 IC when powered by a poorly- rectified AC power supply.


Methodology For our experiment we used two kinds of power (Figure 1): Circuit A uses a DC power source, whereas Circuit B an AC one with a simple low-cost rectification circuit. Several simulations were done to


determine if the low-cost AC supply provides a meaningful output signal. We also assumed the following:


• Troughout the experiment, all components were unchanged to allow fair comparisons between circuits. • Te comparison was monitored aſter


20 March 2021 www.electronicsworld.co.uk


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