I am trying to build an audio circuit with an oscillator releasing a 3000Hz 9V square wave DC. I do not understand why the loudspeaker keeps on exploding in my simulations. I have put an electrolytic capacitor already to block any DC components from the damaging the loudspeaker but it keeps on exploding in the simulation. Am I missing something?

I am using Circuit Wizard 2.00

Here is my circuit:

 

exploding? what does that mean?

 

It won't work, because your discharge path for C3 is via 10,100Ω (R7,R^) but I don't see how it can explode.
(Did a PP3 ever make anything explode?)
A NE555 can get adequate volume out of a speaker with a 100Ω series resistor. Or look for a 64Ω speaker.

 

You need to describe exactly what you mean by the speaker "exploding" in the simulation.

 

You need to describe exactly what you mean by the speaker "exploding" in the simulation.

Circuit Wizard has an Explosion Feature in simulations. It causes the components to explode once they are subjected beyond their limitations. It usually happens when there is something wrong with the circuit.

 

It won't work, because your discharge path for C3 is via 10,100Ω (R7,R^) but I don't see how it can explode.
(Did a PP3 ever make anything explode?)
A NE555 can get adequate volume out of a speaker with a 100Ω series resistor. Or look for a 64Ω speaker.

What do you suggest I should do?

 

What do you suggest I should do?

Download a fire extinguisher app.

 

The circuit has issues, but that exploding thing is strictly a simulator artifact. Change the parameters / attributes / whatever for LS1 to make it a speaker rated for 20 W.

Here is just one of the circuit's issues:

C3 and the speaker's coil resistance form a highpass filter with a cutoff freq of 199 kHz. This is over six octaves above the 555 output freq of 3 kHz, for an attenuation of 36 dB. A bipolar 555 running on 9 V will make an output of approx. 7 V peak-to-peak. Even if the buffer amplifier increased the waveform to a full 9 Vpp (and it cannot), the speaker voltage would be only 140 mV.

The simulator has no problem with this, but the circuit will make a very low audible output IRL.

ak

 

A good way to drive a low-impedance load, such as a speaker, is with a push-pull amplifier.

 

polarized 100nF capacitors have tendency to explode when mislabeled

 

What do you suggest I should do?

you typed this directly after quote suggesting just that... two suggestions in fact:
a) A NE555 can get adequate volume out of a speaker with a 100Ω series resistor.
b) Or look for a 64Ω speaker.

and both of them are to ditch the transistors and drive speaker from 555

 

Circuit Wizard has an Explosion Feature in simulations. It causes the components to explode once they are subjected beyond their limitations.

Then the simulator is off its whack.
Your circuit cannot cause any large dissipation in the speaker, since it can't even generate a small signal there.

 

polarized 100nF capacitors have tendency to explode when mislabeled

While they probably are out there somewhere, I've not seen a 0.1 uF polarized cap.

ak

 

i don't recalling ever running into one of them either
but it looks like they do exist
https://www.digikey.ca/en/products/detail/nichicon/UWP1H0R1MCL1GB/2550795

 

I bought a capacitor kit recently.
I didn't realise 0.1uf electrolytics existed either.
https://thepihut.com/products/200-piece-ultimate-capacitor-kit

Half this kit is a complete waste of time. I assumed lower values would be ceramics perhaps.
There's no info in the description to suggest that they are all electrolytic.

 

Hello,

The second picture shows the opened box with all values present.
You can also see that they are electrolitic capacitors.

Bertus

 

Does anyone know why you would use a small value (say below 1µF) electrolytic capacitor instead of a ceramic, which are non-polarized, more reliable, and generally have better characteristics?

 

Hello,

There seems to be a ceramic capacitor set available;
https://thepihut.com/products/ceramic-capacitor-pack-250-pcs

Bertus

 

and equally not documented.... no list of values or voltage rating. i would never buy something like that, to me that is a scam.

 

Hello,

Sparkfun has a combi capacitor kit:
https://www.sparkfun.com/products/13698
On the documents tab, there is a kit sticker with the values.

Bertus