Sunday, 11 July 2021

Ring light for The Shiz?

No smutty innuendos required here, thanks. I've been meaning to get round to this on my large mill and was thinking it would need to be one of those "angel eye" ring things sold to boy racers. However, thanks to a post by Andrew Mawson on the Madmodder forum, I managed to find a 10" version of this "influencer" light on Amazon at £7.09 including free next day delivery. Bargain buckets. This left me with no option. 

This thing did indeed come next day and included a Xmas cracker "tripod", a flexible gooseneck thing and a remote control shutter thing for smart phones. Those can hit the bin obvs.

I played with mine, took it apart and fiddled around with the scope to see what I had here. There are 2 rows (rings) of LEDs - cold white and yellow. 

The controller switches between one, the other or both of them. However, when you switch between the light colour settings, the current consumption stays the same, so clearly the current in the LEDs is PWM modulated by the SO-8 IC to keep the current within the USB limit. Clearly this means only some of the LEDs are ever fully utilised. And judging by how cool they run, they are barely being challenged. Hmm.

So I removed the controller from the equation and hard wired both rings in parallel. I'd have put them in series but the tracking on the IMS board (aka aluminium single-sided PCB) wouldn't allow that. Playing with the PSU, I can see that a 0.47R metal clad resistor in series with them would give a convenient 2 - 2.5A in the light if supplied with 5V. After running thus for 30 mins, the peak temperature on the LEDs is around  40C and the resistor is around 45C. Heat is the killer of LEDs, so this is the bottom line here. 

The Shizuoka doesn't have a convenient hole anywhere where it's needed but I'm not averse to drilling holes in it, so that's what happened.

I will need to wire it into a PSU at some point but initially I'll see how I get on with it.

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