Hello, I'm just looking for some guidance on a project I'm working on. I have a R503 fingerprint reader and 0.96" OLED display that are powered by a D1 mini which is encased within a 3D printed enclosure. That circuit has been running happily 24/7 for months without issue. I'm looking to add an act…

I get ya, looks like 12mA per GPIO pin and 500mA on the 3.3V and 5V pins. So if my understanding is correct the fingerprint reader and OLED won't come anywhere close to an issue as they're powered via those pins but the buzzer could as it might take up to 25mA which is well over the 12mA the GPIO pi…

[image] burg: I think this leaves me with two options? A transistor to boost the current to what the buzzer might use or to use a resistor limit what the buzzer can take? Given it works fine I suspect it's operating quite a bit under the stated "up to 25mA" listed... Do you know Ohms law? If …

I understand that adding a resistor will reduce the current passing to the buzzer (whereas I probably would want to increase the current passing to the buzzer). Does that mean if I pop the 330 resistor in the circuit and it continues to work then it's all good. i.e. 3.3V / 330 resistor = 10mA. So i…

Yes, that was what I wanted you to work out. It will be less than10mA because some of the voltage will be across the buzzer. One more thing, is the buzzer electronic or elector-mechanical? Anything with an electromagnet in it will produce voltage spikes that will kill the D1 Mini.

Brilliant! Got there eventually thanks. Just checked, sadly it's listed as electromagnetic. Is there anything easy to overcome this (as I'm very limited on enclosure space as-is) or is it likely easier just purchase a different type?

[image] burg: Is there anything easy to overcome this A diode Flyback diodes and why you need them However, I note you said: [image] burg: have got the buzzer running on a secondary test D1 So if it already works on a D1 Mini maybe it's OK, maybe it does not produce lots of high volt…

Yeah the buzzer is working fine on the second test D1 mini I have here (continuous loop of short beeps), I've not seen a diode used on any of the examples I've seen online either. Would I know immediately if it's an issue or could it cause an issue at any time down the line? I have some diodes in t…

I can't really answer you very well. The only way to know for sure if the thing is generating high voltage spikes is to check with an oscilloscope, and I am guessing you don't have access to one. I don't know what buzzer you have so I can't comment. I'd expect if there are high voltage spikes that t…

[image] burg: Would I know immediately if it's an issue or could it cause an issue at any time down the line? Edge cases cause intermittent behaviour. Does that answer it?

Yeah no access to an oscilloscope sadly. I was only asking as if it was a case of "It'll die immediately. If not then it's fine" then I'd have no issue as it's running okay... If there's any risk of it possibly happening down the line I'll pop a diode in to be safe. After a bit of research it sound…

Basic active buzzer to existing project guidance

Projects General Guidance

PerryBebbington August 8, 2021, 6:32pm 17

A diode Flyback diodes and why you need them

However, I note you said:

So if it already works on a D1 Mini maybe it's OK, maybe it does not produce lots of high voltage crap. Only way to know is with an oscilloscope.

Topic		Replies	Views
Choix de type de Buzzer Français	117	1956	October 16, 2025
What is the correct name for a driven passive buzzer 3rd Party Boards	31	762	September 5, 2024
Solved : Possible : more than one buzzer to Arduino nano ? YES Motors, Mechanics, Power and CNC	21	1156	January 6, 2024
12 button wireless buzzer game - ambitious? General Guidance	60	628	September 23, 2026
Piezo buzzer keeps buzzing as soon as plugged in without action General Guidance	8	1098	April 2, 2024

Basic active buzzer to existing project guidance

Related topics