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I have this circuit below where I want to use a buzzer that is 5-8V and has a max current of 30 mA. The VCC supply voltage is about 24 V. I know there are voltage regulators or that I could implement a voltage divider with a Zener diode. However, I was wondering if I could just use the implementation below with a 16V, 500mW Zener diode, and a 200 ohms resistor 125mW. Since we want at least 5v for the buzzer to work, If there's a voltage drop of about 3V on the 200-ohm resistor and 16V on the Zener diode, then the current will be about 3V/200 ohms = 15ma. It's good enough to work with no problems? enter image description here

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  • \$\begingroup\$ Why the 16 V Zener? \$\endgroup\$
    – winny
    Commented Dec 22, 2021 at 8:00
  • \$\begingroup\$ Why not just use a 500 ohm dropper resistor (rated about 1 watt of course). \$\endgroup\$
    – Andy aka
    Commented Dec 22, 2021 at 10:06
  • \$\begingroup\$ Andy, I was also thinking of using just a 1K resistor with at least 500mW. I want to make the implementation simple but still effective. \$\endgroup\$
    – Citi
    Commented Dec 22, 2021 at 18:37
  • \$\begingroup\$ winny, I thought using a Zener diode in my effort to bring the voltage down to not damaged the buzzer, but i think to make it smiple I've could just use 1K ohm resistor with at least 500mw \$\endgroup\$
    – Citi
    Commented Dec 26, 2021 at 1:13

2 Answers 2

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Ok, its two parts more and no zener diode, but I like to use current sources for such problems:

solution with current source

  • Power is dissipated in Q2
  • current is defined by R1
  • solution can regulate over a wide range of input voltages and loads
  • can handle loads with variable resistance
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If you want to use a Zener diode to regulate the voltage, just check out the Zener diode shunt regulator but the voltage drop way is not the efficient way to use it. You can simply get 5 volts Zener diode from its terminals.

https://www.digikey.com/en/maker/blogs/zener-diode-basic-operation-and-applications

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