A circuit where pressing a switch alternates which LED is powered when one turns on, the other turns off..

to accses the demo you can by going to this link

https://falstad.com/circuit/circuitjs.html?ctz=DwYwlgTgBAZgvAIgIwKgFwM6IAwDpsEECsqYIiSeATAVQOx0DM2AHFQGwCcndqIARoiLZUAB0EJhqAG4QhqALaYhAUwC0SFAD4AUFCjAASlAAeiACyd2UKixZRGLczbup4ydqgDu7kVAUAhibS8gD0uvrA0GaS7Ng2dFRQRHE2rG44qHLIhAjhegbRQqnMzinxjuYZCH7ZlAR5EQYAMgCiACKmxfE09uzmPemwmf4A9ogAJiowAQCuADZoavMqE3x1fADmIwIjCvzkNfgo+ZFtnTHlDk5Q7CnXVcM1iuMIUzMLSytrUCAbv9tnr8JH59oc8NgTk1QF1JEgkkhUldetU-OD8IQUFAwCEjgQsRhsn5pBNEBpcOwGHQWMxHFROFQkNxeKcDCBYVdKslbFBzIjUXwcBj8aRcRDIahCSMSRQMXFsAymSwUv02I0CsBNrD+oM+ok0iwBazNRz4VBEfFLNYkOZHr51ZEtZceXzrEQzeZGFQjdCnYg7tYuew7A8fRqAMqwq0uezI1xPPzzMAjNAAC0Q3vywFC4AguiAA

The circuit uses two parallel branches each with a 1k resistor and a 10µF capacitor connected to an LED When the switch sends power to one branch, that capacitor discharges and allows current to flow lighting up that LED The other branch's capacitor charges up and blocks current keeping that LED off Flipping the switch reverses this toggling which LED is on. on.