Monday, 31 March 2014

Lights at last

Lights At Last

Never one to finish anything when there's something else to distract me, a recent burst of activity has seem some progress on several fronts including the lights.

The pictures below show the isolation circuit board which provides optical isolation between the Arduino UNO connected to my laptop and the lights themselves which are connected to their own 48v/12v/5v power supply.
This plugs into the Arduino like a standard shield.

The above power supplies, Arduino and isolator card along with a powered USB hub and the additional 24v power supply for the motion control rig are all contained in a single 'master' unit. This means just one mains socket and one USB cable from the laptop are required to operate the lights and motion control rig from DragonFrame.

Lights isolator board
The four headers connect to 7-pin DIN sockets on the front of the master unit which the lights themselves are plugged into.
Below are some images of the finished prototype lamp.

High Frequency PWM Dimmable LED Lamp

High Frequency PWM Dimmable LED Lamp

 The whole point of this exercise is to create an inexpensive stage luminaire that suits the small animations stages found in various sheds and spare bedrooms around the world. The use of a 40 Watt LED element results in adequate brightness with virtually no waste heat and the use of high frequency (4kHz at the moment) PWM control means no resulting flicker when the lamp is dimmed if the camera exposure period is relatively long (say, 1/100 seconds or more).

The initial dimming test has shown a small amount of flicker in the resulting video (yes, the aperture was used wide open). Further tests are required to confirm the source and, fingers crossed, eradicate it.

1 comment:

  1. Hi,

    You mentioned 10kHz PWM on a previous post, but hare using 4kHz now did you have issue's dimming the lights with the higher frequency?

    Best regards,