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is it possible optocoupler EL817 wiht input 3.3VDC and output 24VDC like below circuit. and if it possible what is the suitable value for the resistor

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Rizkis Walker
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  • 1. EL817 output is not strong enough to directly drive a buzzer. The usual trick is to first drive a BJT which is strong enough to in turn to drive a relay switch (or a buzzer). You might like to skim the following post to get a rough idea on the EL817C/NPN BJT biasing design. 2. If you are going to use a BJT for EL817C, you might like to show your circuit so everybody can help. Cheers. Ref: https://electronics.stackexchange.com/questions/505318/how-to-properly-use-a-relay-module-with-jd-vcc-from-arduino-raspberry. – tlfong01 Aug 12 '21 at 01:34
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    Why would a buzzer need opto-isolation and what current is this? – Tony Stewart EE75 Aug 12 '21 at 01:53
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    please stop shouting. – Hearth Aug 12 '21 at 02:21
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    @tlfong01 okey i will upload full schematic after it finish. – Rizkis Walker Aug 12 '21 at 05:53
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    @TonyStewartEE75 in this case i want to switch on the buzzer by give 24VDC – Rizkis Walker Aug 12 '21 at 05:54
  • If you have a 3V3 signal, say, from a GPIO pin, you can directly drive an active buzzer (Eg, using 4k7 for the front end BJT,, without using any optocoupler. There is also a demo program to beep the buzzer.) Reference: Active Piezo Buzzer Makes Sound On Both Rpi GPIO Low and High Level Signal Asked 2 years, 3 months ago Viewed 3k times. https://raspberrypi.stackexchange.com/questions/97980/active-piezo-buzzer-makes-sound-on-both-rpi-gpio-low-and-high-level-signal. – tlfong01 Aug 12 '21 at 08:57
  • 24Vdc is not a current and buzzers if plastic insulated do not need opto isolation – Tony Stewart EE75 Aug 12 '21 at 10:37
  • @TonyStewartEE75 sorry buzzer spec is : 20mA 24VDC – Rizkis Walker Aug 13 '21 at 00:45

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