Quite a while ago, I made a “tally light indicator” prototype for my uncle’s CamMate. It was only a rough mockup, but functional. Here are the project highlights…

First, the pictures.

Full project gallery:

In the television industry, a tally light 1 is simply an indicator bulb that signals those being filmed, or those doing the filming, that the camera is on. In my uncle’s case, being a professional videographer, the tally light indicator for a CamMate 2 tells him that his camera way up on a 10-20 foot boom is on. Without this light, it would be hard to know for sure if you’re filming.

As with most industry accessories, these things can be very expensive. But such a simple device as this can’t be that hard to make yourself. So he came to me with the challenge.

I did some research and there’s lots of DIY stuff out there 3. But I started from scratch.

The hardest part about projects like this (at least for me) isn’t so much in the electronics, but in the packaging. It’s one thing to make a functional prototype, but then to miniaturize it and put it in a small form factor without the aid of small PCBs is tough. When you’re working out of your garage, there’s only so much you can do to achieve this.

But my prototype worked well enough initially. My uncle reported that it started to fail a while after initial testing. The second step would be to put the electronics on a PCB, miniaturize the components, and fine-tune the optical sensor circuit.


I’ve now added my schematic for download here:

cam light schematic
cam light schematic


  1. Wiki article
  2. which is a boom for a camera
  3. Here’s one

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