![]() Why would the 3.3V logic HIGH scenario cause flickering of the SSR input (MOSFET output)? To me it sounds like the SSR is the culprit. Not sure why it wouldn't be closer to 3.3V?Ĭonnecting the MOSFET gate to 3.3V (not HIGH on the IO pin) yields a constant 0V on the MOSFET output, as expected. Piezo Buzzers: Buzzers are widely used in many applications like car reverse indicator, Computers and etc. I also tried setting the IO pin to LOW and connecting it to the negative side of the SSR while its positive end was at 3.3V, and I measured a fluctuating 0V-0.2V at the negative end.Ĭonnecting the MOSFET gate to GND (not LOW on the IO pin) yields a constant 2.5V on the MOSFET output. By itself the IO pin gives out a constant 3.3V, but when I plug it into the MOSFET gate, it fluctuates, and the MOSFET output reflects this fluctuation. These pulses create a current that uses the vibrations of a metal plate to. I tried using other IO pins on the board, and same thing. The piezo buzzer utilizes ceramics with the piezoelectric effect to generate pulses. Piezoelectric buzzers are regularly used to produce audible signals in alarms and warning devices. A key advantage of piezoelectric buzzers is that, unlike inductive speakers, they can operate in damp conditions. With the 3.3V output of the ATmega32u4 on the MOSFET gate, I get fluctuating voltage on the MOSFET output (should be 0V since I am pulling it to GND, but it's like 0.3V to 2V on my multimeter). buzzer ideal in battery powered applications. SSR relays usually don't require that much drive current.Ĭan't you drive it directly with the pin. The 2N7000 is not really suitable for 3.3volt logic. ![]() That's not a piezo, but a DC buzzer (one that makes a beep by itself). (As a quick verification I also bypassed the MOSFET with the 3.3V directly to the SSR input and it was steady.). Also, I have no idea why they would control the SSR input with the same NPN if it only draws about 5mA?Īnother issue: I tried using the 2N7002 to drive an SSR input, and even though the gate was set to a steady 3.3V the output of the SSR (an AC night light) flickered a lot and the input (the negative, switched input of the SSR) fluctuated on my multimeter. ![]() I was looking at this schematic for a DIY reflow oven controller and they control their buzzer with a small signal NPN (I am assuming their buzzer isn't a piezo, but a polarized one).
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