Need help with a simple project

Thread Starter

Vatch

Joined Sep 21, 2016
4
I am fairly new to circuits(I know how to solder without melting the breadboard) and I have a simple project that I am trying to complete. I want to know how to wire it without breaking anything. I would also like to learn a thing or two.

I have a small sound board akin to that of a greeting card. The board has a button that activates it and plays a sound.
A 5mW laser diode
An 8 ohm 0.1 W speaker
A 2.5 watt mono amplifier from Adafruit.com
And a battery pack that holds 3 AA batteries
An assortment of resistors

I would like to wire the amplifier's out to the 8 ohm 0.1watt speaker and the sound board's output to the amplifier(via removing it's leads from the incuded speaker and connecting them to the amplifier). I also need the button that activates the soundboard to turn on the laser diode. I would like to be able to have all of this run off of the 3 AA batteries without overloading anything.

Any help is greatly appreciated as I have very little idea of how to figure this out myself.
 

ian field

Joined Oct 27, 2012
6,539
I am fairly new to circuits(I know how to solder without melting the breadboard) and I have a simple project that I am trying to complete. I want to know how to wire it without breaking anything. I would also like to learn a thing or two.

I have a small sound board akin to that of a greeting card. The board has a button that activates it and plays a sound.
A 5mW laser diode
An 8 ohm 0.1 W speaker
A 2.5 watt mono amplifier from Adafruit.com
And a battery pack that holds 3 AA batteries
An assortment of resistors

I would like to wire the amplifier's out to the 8 ohm 0.1watt speaker and the sound board's output to the amplifier(via removing it's leads from the incuded speaker and connecting them to the amplifier). I also need the button that activates the soundboard to turn on the laser diode. I would like to be able to have all of this run off of the 3 AA batteries without overloading anything.

Any help is greatly appreciated as I have very little idea of how to figure this out myself.
The laser can be tricky - they're easy to damage.

You need to set up a textbook constant current circuit, set to around 60% of the maximum rated laser current. Couple the audio in via a DC blocking capacitor to modulate the current.

How/where you inject the AC depends on which textbook example circuit you chose.
 
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