AVR Projects

Electronic Film Clapper v1.3

This project came about because I needed a way of marking Video and Audio files for editing. I didn’t wish to use a full size clapper for the job so I designed my own device. I chose to try the idea out on an Arduino Uno, but realising that an ATMEGA328 was a little excessive for such a trivial task, I moved over to a Digispark clone purchased on eBay. This board utilises the ATTiny85 MCU.

The requirement is to have a visual and audio que that is apparent upon editing the separate streams together. I intend to film at 25fps (Frames Per Second) so I determined that a 25ms pulse of light from an LED and an audio pip would fit into a frame. The pulse period is easily changed in firmware, as is the audio tone of the ‘pip’, although I found 4300Hz is pretty optional for my use.

ATTiny85 Clapper v1.2 Prototype

ATTiny85 Clapper v1.2 Prototype

ATTiny85 Clapper v1.2 with Powerbanks

ATTiny85 Clapper v1.2 with Powerbanks

ATTiny85 Clapper v1.2 Visual Que

ATTiny85 Clapper v1.2 Visual Que

When the Electronic Film Clapper PCbs arrived from Hackvana.com I set about making one up. There were no issues. I remembered I’d inverted the USB plug so that the device would plug into the USB Power Bank the correct way up!

On the board, I have included several options:

  • Use either a Digispark board (available on eBay and other auction sites) or a bare ATTiny85 chip.
  • Use either a USB Plug type ‘A’ or feed in power via direct connections (Header compatible).
  • Use either standard small tact switch or larger Omron style.
  • Optionally link across R1/R3 for increased sound/visual que

The Omron switch is a little tight. The holes on the library part need to be enlarged but I have chosen to release this version none the less. A little bit of extra force sees the Omron style switch mounted. Any updates will address this issue.

Construction is straightforward. Start with the lower profile components, resistors, the polarity protection diode etc. and work up to the larger ones. I found the best way to mount the Digispark board was to use standard headers underneath and solder on the top before placing it at the appropriate place on the PCB. This creates a really secure connection. The Digispark can be programmed before or after soldering on. If a bare ATTiny is utilised, it only requires a standard 8 pin DIP socket.

Film Clapper prototype and v1.2 boards

Film Clapper prototype and v1.2 boards

Programming the Digispark is fairly simple. Download the relevant files from: DigiStump Wiki and follow the instructions for installation and connection. I used the standard install to program the bare ATTiny85 via ISP but it wouldn’t work, at least, it would flash but the buzzer emitted no sound. I later (after 3 days of searching!) found out that the usual ATTiny85 libraries I had used didn’t support the ‘Tone’ function which I had used in the sketch. I managed to find this library: Arduino-Tiny on this page all about a custom tone generator library.

I built a bare ATTiny85 version to test the new PCBs, for speed and so I wouldn’t use up another Digispark board. I could also utilise the pre-programmed chip from the v1.2 prototype.

Electronic Film Clapper v1.3 PCBs Front and Back

Electronic Film Clapper v1.3 PCBs Front and Back

Electronic Film Clapper v1.3 mounted on Power Bank

Electronic Film Clapper v1.3 mounted on Power Bank

Here are all the files necessary for fabricating the Electronic Film Clapper v1.3:

  • Electronic Film Clapper v1.3 .SCH schematic file
  • Electronic Film Clapper v1.3¬†.PCB board file
  • Electronic Film Clapper v1.3 Gerber .ZIP file
  • Electronic Film Clapper v1.3 Parts List — file
  • Electronic Film Clapper v1.3 Schematic .PDF file
  • Electronic Film Clapper v1.3 Sketch .INO file

The entire directory of resources is available at: Electronic Film Clapper v1.3

I tried using a 78L05 on v1.2 to regulate the incoming voltage, but it turned out to be too low powered and I bypassed it. In v1.3, it is completely removed. I did include the polarity protection diode in case of mistakes being made with the direct voltage input. If USB is used as a power source, there should be no issues. Remember though, the USB Type A plug sits on the reverse of the board for correct polarity.

Creative Commons LicenseElectronic Film Clapper by ProjectAVR – Steve Smith G0TDJ is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. All files and information is published in the spirit of Open Hardware/Open Software


ZAViouR – Z80/AVR Hybrid board

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