I want to create a RL circuit that has a dc voltage source, lamp, switch, R and L elements are connected in series. How can I design the circuit so that the lamp flashes from the moment the switch is turned off?

The lamp has no value, just to understand the energy use.

  • $\begingroup$ You have specified how you want everything wired and then asked us how to design it. Edit required. $\endgroup$
    – Transistor
    Jan 22 '21 at 23:56

Try this.

enter image description here

Figure 1. A simple snubber indicator.

  • Pressing SW1 will pass a current through L1. D1 will be reverse biased and LAMP1 will remain off.
  • Releasing SW1 will cause L1's top terminal to switch to a negative voltage, D1 will become forward biased and current will flow through the lamp.

You can estimate the pulse duration time constant from $ \tau = RL $.

You probably want to set the system up so that when SW1 is pressed the voltage on L1 is equal to the LAMP1 rated voltage. That way you get the best chance of seeing a flash with minimum chance of burning it out.


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