General electronics , digital signal to the base of a npn transistor.

Thread Starter


Joined Jul 20, 2019
I need to send a digital signal to the base of a npn transistor. I need the frequency to be around 100 times a second. This will turn on a buzzer 100 times a second and create a specific sound.
Help me
Thank you


Joined Jun 5, 2013
If you really have a buzzer, you would send it a steady voltage to make a sound.

If it is a speaker, a 100 Hz signal would make it buzz.



Joined Jan 21, 2019
Having played with active and passive piezo buzzers. Active buzzers need only DC. Passive buzzers work on an AC signal. You can change the tones on active buzzer using a square wave but passive is the way to go if you intend to send it pulses.

555 is pretty simple to achieve but so is a little 8 pin AVR or PIC with less components and less current. With a Microcontroller you could switch it change frequencies blink LEDs and all sorts of fun stuff. I suggest an ATTINY45 or 85 depending on how efficient your coding is.

100hz on a passive will probably sound more like clicks. Most of them are designed for much higher frequency. Near 2k or so depending on the buzzer
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