First of all I'd like to say, Hello, I am new here and this is my first post. I have a rather interesting question regarding an even more peculiar project that I am working on.

I'll give my background knowledge first so I can hopefully avoid a lot of follow up questions trying to understand your replies. I got started in development board circuitry and electronic engineering about a year ago. I have novice to basic knowledge of Arduino codage and introduction knowledge into Python code used on Raspberry Pi units.

As for my project, I am making essentially sound box. I am utilizing a frequency generator to first create a wave that is then made into either sound via my speakers or visual via my leds. Currently I have a 8038 Signal Generator running at 9VDC creating triangular, square, and sine waves in a range of 5-450kHz. I then run the output through a K2572 Stereo Pre-Amplifier running at 9VDC as well. the output from the pre-amp is then fed to my speaker or led.

I am suppling my generator with straight voltage. I was wondering if I can use a NE555 Pulse Frequency Duty Cycle Adjustable Module to act as a pulse switch supplying 15VDC power through the generator to create my Frequency Wave that can then run through the Pre-amp powered at straight 15VDC ending with output through my speaker? I really don't want to fry any one of these 3 circuits or the whole lot for that matter. I'd appreciate any advice and also advice on a better speaker. I am considering using my two 3W 8ohm speakers to replace my old single salvaged speaker that I am currently using if it is advisable to do so.

 

Welcome to AAC!

The output voltage of the 8038 is sufficient to drive an audio amplifier. You don't need a preamp.
What you need is an audio power amplifier to drive your two 8-ohm speakers. There are many compact stereo class-D amplifiers available.

Do not pulse the power going to the 8038. That will not work well. If you want to modulate the sound, do this at the output of the 8038 before the power amplifier.

What is it that you want to do with the sound output in terms of modulation?

 

if I can use a NE555 Pulse Frequency Duty Cycle Adjustable Module to act as a pulse switch supplying 15VDC power through the generator to create my Frequency Wave

Have you looked at the Vout for the NE555 on its datasheet? Vout=12.5V @ 200mA or 13.3V @ 100mA. So directly, NO, but you can drive a transistor switch supplying 15V @ a decent current.
NE555.pdf (datasheetcatalog.com)

And Welcome to AAC!

 

What you need is an audio power amplifier to drive your two 8-ohm speakers. There are many compact stereo class-D amplifiers available.

What is it that you want to do with the sound output in terms of modulation?

I have a Half Watt Amplifier circuit I made that runs 2 speakers. It's hooked up via an audio cable to my fm radio and boosts the volume of my radio well beyond where I need it. I assume??? that will work sufficiently as the Amplifier instead of my current pre-amp?

In terms of modulation I am creating a system that I can mount to my drone used in Search and Rescue. Essentially I will be creating a 2 tone or single pulsing tone siren that I can have active while the drone is airborne or landing. So that Rescue teams can locate it faster and so that I can better alert those we are rescuing that there is a search drone approaching. I know there are systems I can buy and install but they are way more expensive than what I can make one for.

On a side note, I have already created a high Intensity LED Strobe using a 555 chip that I intend to incorporate into this project. Once completed.

 

Have you looked at the Vout for the NE555 on its datasheet?

Yes, actually I am using the datasheet for the whole module itself, not just the NE555P.

 

If you want a two-tone alert signal then 8038 is overkill. You can do it with two 555-timer circuits.
I would not use NE555P if you want to conserve power. Use a CMOS version such as LMC555, TLC555, ICM7555.
If you are going to mount this on a drone you can replace the audio amplifier and 8-ohm speaker with a piezo-electric transducer. This is going to weigh a lot less.

 

If you are going to mount this on a drone you can replace the audio amplifier and 8-ohm speaker with a piezo-electric transducer. This is going to weigh a lot less.

I am aware that it is a bit overkill but I am working with what I have on hand at the moment. I would have to go order the stuff to go with a timer circuit and piezo transducer. Currently I am under my total load weight for the drone by about 4.5pounds for actual equipment on the drone. That doesn't include the cargo capacity that I can subtract from if I have to. My question is in regards to the transducer is yes I am reducing the weight of my circuit but would I be loosing volume. The sound must be hard over the rotor wash and be heard from atleast 100-200 feet away. Can a piezo transducer produce the volume needed to do that?

 

Really, for an audio signal to aid locating an item like that, a pulsed piezo sounder will make more noise and use less power. And if it can couple to some resonant body part the beeps will be much louder. And the higher pitch is easier to localize.

 

I really doubt that a speaker driven at 1/2 W would be loud enough for your purpose. I hav a two tone piezo that is ear-piercing when driven by a little 9V battery.

 

Well I guess I will set my current circuit aside and make the long trip down south to the electronics supply store I go to and pick up some piezos. This will be a good excuse to get more then what I need.

 

There are two different flavors of piezo sound makers. One variety is powered by DC and includes all of the electronics to produce sound. They generally weigh more and are often larger.
The other flavor is strictly a transducer, with no associated electronics. They require an external oscillator/driver. I have driven them with a simple CD4049 IC and a one capacitor one resistor oscillator, running on 3 AA cells, using 4 of the inverters as a bridge driver circuit.