I need help with the output of a standard astable 555 timer circuit.
Led2 constantly glows dimly when the output is low but does brighten when the output goes high. Led1 for some reason always stays on, even when the output from the 555 is high. Led2 works correctly if I disconnect Led1.
I thought that my resisitor values may be to low? I calculated the resistor values to give me 20mA through Led1 at 2V, 15mA through Led2 at 1.9V and 10mA through the optocopler at 1.18V. Are my calculations correct? Have a placed the optocoupler protection diode (D) correctly?
Any help will be appreciated.
Led2 constantly glows dimly when the output is low but does brighten when the output goes high. Led1 for some reason always stays on, even when the output from the 555 is high. Led2 works correctly if I disconnect Led1.
I thought that my resisitor values may be to low? I calculated the resistor values to give me 20mA through Led1 at 2V, 15mA through Led2 at 1.9V and 10mA through the optocopler at 1.18V. Are my calculations correct? Have a placed the optocoupler protection diode (D) correctly?
Any help will be appreciated.
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