3/2/2024 0 Comments Supply piezo buzzer![]() I don't know why you sketched the wrong circuit with three opamps. The maximum allowed input to an LM386 is plus or minus 0.4V so you blew up its input transistors by feeding it half of +7.5V. With a +7.5V supply, its output power into an 8 ohm speaker is only 0.25W which is less volume than a cheap clock radio. The LM386 is made to use a single-polarity 6V to 9V supply, not 32V. Then an attenuator and coupling capacitor can feed a 10k volume control that feeds the input of the LM386 power amp that drives a speaker. The Function generator opamps use a single-polarity positive supply and are biased at half the supply voltage with the two 10k voltage divider resistors. An LM386 has internal biasing and has internal negative feedback so they cannot be used in the function generator circuit. Opamps do not have internal biasing and do not have internal negative feedback.Ģ) You said you are using LM386 POWER AMPS instead. Thanls for everyone who can give some helpĬlick to expand.Yes you are making a HUGE mistake:ġ) The function generator circuit is designed to use OPAMPS. Why might be that and what may be the solution. The voltage levels of whole circuit was getting bigger with time. Might this be a problem?Ĥ) When measurin voltage levels. Secondly i adjusted the voltage divider resistors to get a precise half voltage but the results is same again.įor the voltage follower should i also connect a voltage follower to directly my adaptor?ģ) As i said i used LM358N but in the link is used a different opamp. But i either could not get a square and triangular wave or the opamp got burnt. I connected a voltage follower to the halfvoltage. So as i understand voltage level is appropirate?Ģ) While experimenting in the voltage divider part i measured 2-3 volts for the halfvoltage as the full voltage is 7.5 volts. And my adapter gives 7.5 volts approximately. In its datasheet sheet its single supply operation is okay from 3 volts to 32 volts. I use LM358N opamp which is not the opamp in the link. But in implementation i don't know how many opamps i burnt.ġ) As single supply i am using an adaptor (not the big power supplies in the lab i think this has something to do with loading effects). In similuation(multisim) everthing is fine with these values. ![]() Therefore i searched internet and i found ( **broken link removed**) this circuit. We can implement it with double supplies(+VCC, -VCC) but single supply has bonus and to better understand this i want to use single supply. In my lab project i have to drive a piezzobuzzer(external drive but since i do not have it right now i connected a pc hoparlor ) with a triangular wave and get different frequencies and therefore different musical notes. However i have to buy an external driven buzzer so that it will produce a musical note according to he frequency of the driving waveform.Īnd also if it is right am i going to just connect buzzer between the circuit ground and generator output? The conclusion from this seems to be my buzzer is self driven and will always give the same frequency and does not need ac waveform. So i made my homework and searched the internet and all i could find is some buzzers are externally driven and some buzzers are self driven. And it always give the same sound Eb7(also not a change in the feeling of the sound: same tone). I built the circuit and i measured the musical note coming out of buzzer using my guitar tuner program. By the way my function generator includes a square wave and triangular wave generator and single supplied so the output is above a dc avarage level with respect to ground.( **broken link removed**) Now i am assuming that(since after a search for one day, i could not found anything about that, I think the days buzzers are driven with opamp is ancient) i have to connect buzzer in betweeen directly the output of the opamp and ground levels and the buzzer will sound the "musical note" according to the given frequency. I had buzzers from last semester(THDZ written on them, circular, no other information). In my lab project i have to use a buzzer in a part and produce a note of certain frequency.
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