As I suck on electronics I have a few questions about connecting the mbed to the singing fish Billy Bass.

I opened up my fairly recent Billy (bought in 2009 for this purpose), I saw that he has only two motors now. Looking at some older examples (Marsette Vona's) Billy seems to have had three motors before: one for the mouth, one for the body and one for the tail. In my version the body motor controls both body and tail (by changing rotation direction).

My "scientific" tests showed that grounding the body motors different pins made Billy move his body or tail. What kind of parts do you suggest to control this with the mbed?

My other question regards the sound. There is a 8 ohm 0.5w speaker (probably same as before) installed. How do I connect it to the mbed? I suppose you can't connect the speaker directly to the mbed, but you would need some sort of amplifier? How do you control the output sound volume?

You are looking for the L293D chip, a stepper/DC moter driver. It can power two motors to go forward and backwards. This is if your motors are DC of course. It costs about $4 and is very easy to impement. Here is the code that I use with this exact chip: Motor

Thanks for your quick reply! That L293D chip seems to be just what is needed, thanks!

Any ideas of what to use for sound amplifier?

Well for that you could use a less obvious source such as a TV or a stereo, pretty much anything with a volume control and a speaker can amplify your source.

May be this ? http://www.mikroe.com/en/tools/audioamp/

Thanks again for your advice! The LM386 seems to be the perfect IC for the audio amplifying.

Looking at the original circuit board there are no ICs at all. Everything seems to be made of a few transistors(?), resistors and capacitors. Looks pretty old-skool, probably some sort of cheaper approach there...

I was silly enough to think I knew enough about electronics to purchase an mbed NXP LPC1768 controller to reprogram my brother's billy bass. I wanted to add an audio clip from the band "Country Porn" I'm proud to be an AH from El Paso. I guess I wasted some good bucks unles I can get some cheep help?

All the best,

More money than brains

David Gury wrote:

I was silly enough to think I knew enough about electronics to purchase an mbed NXP LPC1768 controller to reprogram my brother's billy bass. I wanted to add an audio clip from the band "Country Porn" I'm proud to be an AH from El Paso. I guess I wasted some good bucks unles I can get some cheep help?

 

David, it might not be as hard as you think, getting the billy bass to play a song clip is fairly easy. In fact, with a simple SD card with the song on it, you can get the mbed to play that song through the analog out pin. If you connect this to a speaker, you should be able to hear the song. For the code just visit: http://mbed.org/projects/cookbook/wiki/WavePlayer

After you got your song playing, all you need to worry about is driving the motors. I good way to get bi-directional movment from the standard DC motors use the L293D chip like I mentioned above. It can power two motors to go forward and backwards. Here is the code that I use with this exact chip: Motor

This forum is also great, as there are many people now using the mbed with different experence levels so if you have any issues there is always someone willing to help you out.

Maybe as a suggestion someone who has created a Billy Bass with the mbed could post their notebook page with steps and code for others that are trying to learn. It might be a great first time learning experience for new mbed owners.

I did (or rather am doing) just about that what Vlad said. My project is still 'under construction', but I'll post a notebook about it when it gets ready (I'm a bit time stressed right now, not much has happened on the project). Basically I added a sd card, put a song on it, used the waveplayer to play the song on the analog out pin and moved the motors with the help of Vlads motor program. I pulled out the original 'brain' completely and added the mbed to be the new brain. See my questions on the forum and notebook page for more info.