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Try the simple 555 testing-circuit of Fig. 5. to get you going, and test all your 555 timer ic's. I build several for friends and family. I bring my own tester to ham-fests and what not to instantly do a check and see if they are oscillating. Or use as a trouble shooter in 555 based circuits. This tester will quickly tell you if the timer is functional or not. Although not foolproof, it will tell if the 555 is shorted or oscillating. If both Led's are flashing the timer is most likely in good working order. If one or both Led's are either off or on solid the timer is defective. Simple huh? |
