Star Wars - R2D2 Cake for Nephew

Thread Starter

HvEdtg83

Joined Dec 19, 2013
4
I'm trying to figure the easiest way to wire up a R2D2 cake we are making for my nephew. The electronics would be worked into the cake and insulated from it.

I would like to have a button that he can push which would simultaneously trigger a red LED (mounted in a bezel) and initiate a 9V sound recording module (from Radioshack) that I would use beforehand to record the R2D2 sound effect from one of the movies.

Ideally the red LED would come on and stay on, and the recording module would play back only once unless the button was pressed again.

I'm thinking it can be done with
- battery + battery holder
- recording module
- resistor
- red LED + bezel
- on/off push button

Would it be possible for me to wire up the recording module as normal and simply insert the LED portion of the circuit in between the battery and the recording module?
Any advice is appreciated
 

GopherT

Joined Nov 23, 2012
8,012
If you have a soldering iron, you can add the circuit you describe to the battery wires of the sound module from Radio Shack.

Use a 330 ohm resistor if you are using a RED LED.
 

Thread Starter

HvEdtg83

Joined Dec 19, 2013
4
I am competent with a soldering iron - should have mentioned that in the initial post.
Would it be a DPST switch that I need? Or could a SPST switch be used because the LED has a low draw?
 

Alec_t

Joined Sep 17, 2013
11,870
If you want the LED to stay on throughout the playback you will need a timer or latching circuit.
Does the sound module need a brief pulse to activate it, or a continuous voltage at its trigger input?
Can you give us a link to the module's datasheet or spec?
 
Don't be tempted to insert it into the mix before the cake is baked :D.
;) Thats what I had running through my head. Otherwise it seems like it will be layers stacked one on top of one another? So it will be like a standing upright R2D2 and not just a flat picture of R2D2. Its a cool idea, id like to see it. Id also hate to see it demolished! :eek:
 

GopherT

Joined Nov 23, 2012
8,012
I would put it in a ziplock bag and put it right in the cake. Add the battery when it is done. What could go wrong?
 

Alec_t

Joined Sep 17, 2013
11,870
Ideally the red LED would come on and stay on, and the recording module would play back only once unless the button was pressed again.
From my reading of the write-up for the module, one button press turns playback on and it loops continuously until the button is pressed again to turn it off. So the power supply to part of the circuit is latched. If you could wire the LED (plus series resistor) across that latched supply you'd get nearly what you asked for.
 

tindel

Joined Sep 16, 2012
764
If that's the case, I think you could also add a 555 circuit to turn things off at ~20sec. One button press does everything. This would be extra credit though.
 
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