Are there any good non flammable spray paints for cardboard.
I am building a lm386 amplifier circuit and I am using a cardboard chassis.. aka cigarette pack or other cardboard containers.

The power supply will consist of a 9 volt battery. The amplifier circuit will be a lm386. And the speaker will
be an 8 ohm speaker.. 1/2 watt.

I might use a voltage divider for the 9 volt battery.. hence 1k ohm + 1k ohm in series to ground and a node
between the two resistors to supply 4.5 volts for the circuit.

 

As to cardboard paint which is non-flamable I have no idea but would consider using a small plastic bud box or similar for the project.

Using two 1 K ohm resistors to derive 4.5 volts likely won't work. Remember that when making a voltage divider circuit one of your resistors will have the load in parallel with it. I would look towards a buck converter to get 4.5 volts from a 9.0 volt supply. They are very common and inexpensive. Just define your requirement for current and choose a suitable buck converter.

Ron

 

Your voltage divider produces an output current much too low to power the LM386 amplifier. Also, the voltage will not be 4.5V, instead it will be much less and drop lower with the audio modulation.
If you want 4.5V and a maximum output power of only about 0.1W into 8 ohms then use three AA alkaline battery cells in series.

 

As the cardboard is flammable, whether or not the paint on it is flammable probably won't make much difference to the overall flammability. Are you expecting your 1/2W system to burst into flame?

 

First comment on the 9V battery: Sounds like the TS (thread starter) is trying to make a dual supply out of a single 9V battery. As for a load across one of the two 1KΩ resistors, if this IS a dual supply then the same load (in theory) will be the same across the other side.

Second comment: The 9V battery being divided by 2KΩ's of resistance will draw a continuous current of 4 1/2 milliamps. That's not a lot, but over time your battery will be dead. And not over a long time either. In just a few days your voltage will probably be below a useful voltage. Of course, that will be further diminished by the amount of power being used by the amplifier(s).

Suggest you follow the advice of those who've built amps here before. I haven't, so I can't really offer any practical solutions. However, if battery life is not a concern - - - then the 9V solution is a possible solution. However, as others have pointed out - the amp will draw a fair amount of current (haven't done the math). So a 9V solution might not be the best way to go.

That's all I can add to this thread. 'av' a g'day.

 

VHT High Temperature automotive paint.
Max.

 

About sixty years ago I traded about 8 parakeets for a transistor radio in a cardboard box, much like a Marlboro box of the time. It was powered by a 9V transistor radio battery and it never caught fire. This should give you a little comfort.

 

About sixty years ago I traded about 8 parakeets for a transistor radio in a cardboard box, much like a Marlboro box of the time. It was powered by a 9V transistor radio battery and it never caught fire. This should give you a little comfort.

In the early 60's I made money building Transistor radios from kits, powered by the ubiquitous PP9.
Then the Japanese entered the market!!
Max.

 

This does not look like the 006P we know today, except the contacts are similar.

 

This does not look like the 006P we know today, .

This wasn't today, but 1960!
I guess you can still get them!
Max.

 

You don't need to supply a virtual ground or 1/2Vcc bias to the LM386. It will automatically bias its output at 1/2 the supply voltage!