Synchronizer (Electronic "Clapper-board")




Introduction: Synchronizer (Electronic "Clapper-board")

When talking movies where just starting up,a problem arose.How would one be able to combine the image from the film,with the sound written in a studio sound booth?
That's when the clapper board was invented.It's purpose is very simple.To provide a point by which image and sound can be synced on.
That is achieved by having a wooden board with a stick on top.That way when it's hit,all the editor has to do is find the first frame that the clapperboard is closed,and the first frame on the audio track that the "crack" sound is heard.
Even though tecnology has improved since the 30's the closest thing to an electronic clapper board that exists is a plastic board with LED's on it,that display the timecode.
Synchronizer is completely electronic.

For more info on the clapper-board go to wikipedia's entry at

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Step 1: Materials and Tools

You will need the following materials and tools:

9 volt battery
9 volt battery clip
piezo buzzer
2 LEDs (I used 2 red 3mm LED's but you can use any colour and size you want)
2 resistors for the LEDs
Momentary switch
Hobby box (mine was a mentos gum box,that was exactly the right size)
Electrician's or gaffer's tape.

Assuming you are using exactly the same materials as I did,it will only only cost you about 5 euros.
This is what I paid.

1.5E for the gums(!),1.8E for the buzzer,the clip,and the switch.
I had the LEDs from some other project.
Finally you can get a battery from anywhere around 1E up until 5E.Mine cost 2.4E.

Hot Glue Gun
Soldering Iron
Drill (very optional)

Step 2: Cutting,Drilling and Glueing the Box.

You need to cut the box in order to have access inside,and make your connections.
Unfortunately while cutting it,me and my friend managed to break it in two,and we didn't have a spare one.So we had to make some creases for the LEDs to sit on the half-cut bottom.
Ideally you'll want to cut right before you reach the bottom so it stays in one piece,and you can make your holes for the LEDs there.
You can use a drill,to make the holes,or you can try to dig out a hole with the blade.Also make a hole for the switch,and another one for the buzzer's cables,near the bottom.
Once you do,you'll need to place you LED's in their positions and hot glue them.Same with the buzzer.
Finally you need to add the switch.It's your choice whether you want to glue it or not,since it's going to fit just barely,and the solder on the other side,will keep it from falling anyway.

Step 3: Soldering

Now it's time to solder your connections.Solder the resistors to the positive leads of the LEDs and then all the positive leads from the 2 LEDs and the buzzer to one end of the switch.You can use a small piece of cable to make it easier if you want.
Then solder the positive lead of the battery clip to the other end of the switch,and the negative leads of the LEDs and buzzer directly to the negative lead of the battery clip.
To make sure everything's wired up fine,you can place the battery and try it out.

Step 4: Sealing It Up

Just place the other end on top,and seal it up,with either hot glue,or electrician's tape.
I wanted to use black gaffers tape personally,so that it wouldn't look that bad,but I didn't have any left.
You can try to use other color hobby boxes,switches,or LEDs for a personalised Synchronizer.
If you do,leave a comment or even a photo.

Step 5: Things to Add

I wanted to submit this in time for the LED contest,so there are a few things I left out,to have it on time.
These are things I need to add.

*Redo it,without cutting the box in two.
*Add video and audio of synchronizer in action.
*Change Power Supply.9 Volt battery fits just barely in the box,so i wanted to use button cell batteries to reduce the mass.
*Add more photos,and hopefully have them focused.( My internet connection is trying to upload a 3MB picture,for the past 10 minutes!) DONE

I will update this instructable as I add these things.

Thank you for reading my tutorial,and please leave a comment.

Photos are up.

Participated in the
Art of Sound Contest

Participated in the
Get the LED Out! Contest

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    7 Discussions


    8 years ago on Step 3

    I still don't see how it syncs, is it the click of the switch that it syncs against?


    Reply 8 years ago on Step 3

    When recording video and audio in different devices you need to have a way to sync them...That is why a clapper is used..Once the clapper closes it produces both an audio mark (the clapping sound) and a visual mark (the clapper being closed).
    Here instead, you have the LED's turning on as the visual mark, and the buzzer going off for the audio.


    10 years ago on Introduction

    The reason for the sync is usually that scenes are not taken in order so even you may be able to sync the sound with this you still need the info on the take and scene and where in the film this scene has to be placed. A 'clapper-board' is still more useful (because of all the info provided), as if you film in sequence there is only the need to sync the sound once and for this, this device is good enough but you may just clap your hands or two hard surfaces together to get one sync only.
    Still a nice idea, but you should develop it further with a timer starting to run etc.
    Peace and regards.


    oupps mistake i fixed 1 tip for the batterys is to use an opened the 9 volt and put those button cell batterys in ur thingy u made dont pay rip off prices on button cell batterys get them from a 9 volt to save many $$$$$$$$$$$$$$$$$$


    Reply 10 years ago on Introduction

    thanks for the tip.I've seen the video that showed the hack but I'm pretty certain,that the battery i used on the instructable doesn't have button cell batterys in it.I'll look for the battery when i get home. Again thanks for the tip,and please vote if you don't mind.


    Reply 10 years ago on Introduction

    I know.But unfortunately my internet connection was messing up yesterday,and I couldn't upload them.I hope to have them uploaded by the end of the day.