The A Team music box

August 24th, 2008

After the success of my Star Trek fight music box I decided to make a new music box dedicated to one of my all time favourite TV programmes – The A Team!

The A Team is a show I remember very fondly from my childhood. I was 10 and on a trip to the UK to visit my Grandmother and I distinctly remember watching an episode of The A Team when I was there. I could always remember details of it vividly and I also remember returning to NZ and being thrilled when The A Team finally came on TV here too. When you’re a 10 year old lad TV really doesn’t get any better than The A Team.

Fast forward to now, 25 year later.  Recently I rediscovered this programme and have been watching them all over again, right from the start. From the first episode where Face wasn’t played by Dirk Benedict to where I am currently up to in season 4, the ‘Cowboy George’ episode (yes, Boy George really was in an episode of The A Team). I decided that this was a good time to pause and reflect and create this little device as a tribute to this wonderful show. After re-watching all the episodes (the one I remembered from all those years ago turned out to be the second one) I seriously now can’t go out to my garage to work on projects and weld without The A Team theme playing inside my head!

I find even now, as an adult, I still get the same enjoyment and pleasure watching these episodes. Sure they are cheesy, over the top, sexist, violent and generally not what you can consider quality drama but I love them! According to Wikipedia a review at the time said “The show is made for the average 10-year-old intellect which presumably has a desire for lots of car chases, flying bullets and punch-ups.” I am happy to say I still retain some of my 10 year old intellect! Virtual web mistress would be proud (she once told me I am very much in touch with my inner child). In a recent conversation with a work colleague, who said I really must try to make it up to our LA office one day, I told her I already have a plan of things to do if I ever do make it up there. It’s a simple, two step plan:

  1. Visit Disneyland (something I also did when I was 10)
  2. Hire The A Team

Since a trip to the US isn’t likely anytime soon I have instead amused myself creating this little device. My A Team music box.

The first music box used a now obsolete voice recording chip. For this new box I have used a HK828 voice recorder/playback IC made by Honsitak. This neat little chip is a complete voice recorder/playback device on one IC with a minimal number of external components required. Amazingly it is even available locally from Jaycar Electronics cat. number ZZ8200.

This little chip allows you to record audio and play it back directly from the chip with no external amplifier. It will run happily on 6 volts meaning it can be battery powered and you can feed an audio signal (in my case my PC headphone output) straight into it via a de-coupling capacitor. It has several modes of operation and by changing one resistor you can vary the sample rate (hence the recording time) from around 30 to 60 seconds. The longer the recording time the lower the quality.

In my music box I used a 22K oscillator resistor to give me about 35 seconds recording time. One interesting little thing I found is that if you vary this resistor while the chip is playing back the playback will speed up and slow down accordingly. Just for fun I replaced the fixed resistor with an LDR and got all kinds of amusing sounds from the thing by waving my hand over the top of the LDR!

If you examine the datasheet (available from the link above or from the Jaycar site) you will see the chip supports several modes of operation.  I am using ‘tape mode for auto rewind’ since I only ever want to record one long message. This mode simplifies the user interface for the box and I only need to have two buttons on the box. A play/stop button and a record button. Here are some pictures of the device below:

ATeamBox_1 ATeamBox_2 ATeamBox_3 

The A Team music box.

The box has two buttons on the top and a 3.5mm audio jack on the front. Also visible on the front is the back of the speaker and several small holes to let the sound out of the box.  The red push button is the play/stop button. You press this once to start playing and press it again to stop. If you don’t stop it the recording will play through to the end and then stop automatically.

To record you plug in a lead to your audio source then you press and hold both the red play and black record buttons for the duration of the recording. To stop the record button from being pressed accidentally I made a special cover for it. I took a small pilot light (Jaycar cat. no SL2622)  and bezel and pulled it apart. These little lights have a chrome bezel that passes through the panel and is secured with a nut on the back. The actual bulb holder screws into this from behind. On the front is a small green plastic cover that can also be unscrewed. I simply unscrewed the bulb holder leaving just the bezel and it’s cover. I then used a standard small push button and simply hot glued it into the bezel from behind. This creates a very nice looking recessed push button. With the little plastic cover in place it hides the switch entirely meaning you can’t accidentally press it.

switch

Creating a recessed push button using a pilot lamp bezel.

You can see in the top pictures how everything (just) fits inside the box. I used a four AAA cell holder for the battery and the speaker is actually inserted ‘backwards’. That is it points into the box rather than out. The only way I could get everything to fit inside the small plastic box was to put the speaker in this way around and cut a hole to allow the magnet on the back of it to pass through the lid. I drilled two holes near the speaker to allow the sound out and finished them off with 5mm LED bezels and a small piece of black felt under each one.

One thing to note about these little project cases is the crappy screws they come with to hold the lid on. The screws are very long and self tap into holes in the box. It can be quite difficult to get them to screw in, especially considering the screw heads seems to be some bizarre size that a standard Philips screwdriver bit won’t fit (and no, they aren’t Pozi-drive either). Once you do get the screws in properly you need to be careful that when you remove and replace them later you start the screw in the same thread that is already there. With plastic boxes and metal screws it is easy to end up cutting a new thread into the box which will eventually end up wearing out leaving no thread at all. And none of us likes to have loose screws! The way to avoid this is a simple little trick. When you replace the screw turn it slowly backwards first. You will hear, or more likely feel, it drop into the original thread. Then start screwing normally! This trick works for starting off any screw in it’s thread actually.

Once everything was wired up and installed in the box I simply recorded a portion of The A Team theme onto the box. Of course you can record anything you like into it easily.

Here is a little film of the finished box in action!

Yes, I know the recording finishes rather abruptly but that’s the problem with only a 30 odd second record time! Still, for most people the novelty has worn off before they reach the end anyway!

Any 10 year old will love it though :)

 

6 Responses to “The A Team music box”

  1. Amber Says:

    Here I was searching for the meaning of life, now I think I have found it. thank you!!

  2. Ed Burden Says:

    This is a great use of this recording chip! I like the Star Trek one too! I built something similar a few years ago using an obsolete voice recorder chip from Radio Shack but it didn’t have very good sound quality. I want to make one of these with several “sound buttons”. Pressing each one would give a different sound lasting about 5 or 10 seconds. The data sheet for the obsolete chips shows something like this but I was never able to get it to work. I’ll have to check out these new chips that you used. Thanks for rekindling that spark in my brain!

  3. Anand Says:

    An Estimable music box with a sound performance.

  4. Barney Says:

    Hi, I’ve just built a project with the HK828 chip. I’m having a few problems with hum in the recordings, but more annoying is it records ok, but when you play it back you get 1 or 2 patches in the message when the recorded sound drops out! If you play the message again, it still drops out in the same place. Sometimes the dropouts are near the start, sometimes near the end. Unpredictable.

    Wondering could you send me an email, you might be able to shed some light on the problems – or share some tips you came across when using this chip.

    kind regards
    Barney (nbw9969@yahoo.co dot nz)

  5. Samantha Says:

    You don’t know how bad i want the star trek one, haha. Very clever! :)

  6. Ben Says:

    Your trick of turning a screw backwards in its threaded hole until it “drops” into the beginning of the threads is a good one. I’ve been doing this for a long time.

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