L0wbob2017
Mixing light is fun!
can you pls explain why the 5k resistor in series? why not use a 100k stereopoti?
Lighting COB or driver upgrade
- Thread starter Baxterwolfe
- Start date
can you pls explain why the 5k resistor in series? why not use a 100k stereopoti?
Jimmyclone
White Light Warrior
The 5k resistor in series, protects your cobs. You do not want to dim your cobs below 10%. If your only dimming one driver you would use a 100k pot and a 10k resistor.. This will always show 10k of resistance to the driver and not allow you to go below that. If your dimming 2 drivers together from one dimmer it should be a 50k pot and a 5k resistor, this will show 100k/10k to each driver.. This is done for protection purposes only.. You could use a 100k/10k on 2 drivers but your dimmer will go 20-100% at only half a turn.. You will have dead travel on your knob.... Hahahaha..
"Dead travel on your knob"
Cheers
"Dead travel on your knob"
Cheers
L0wbob2017
Mixing light is fun!
well i've been using a 100k poti only and it works like a charm.
When the driver has a dimming channel and gives a range of 1 - 10 V DC for dimming then why should i take 110k ohm instead of 100k?
why dont u want to dimm the COBs lower than 10%? what kind of protection is this?
Using a 50k or 20k ohm poti for only one driver would be useless because the driver would not turn up to full power even if the poti is set on max resistance, thats for sure.
But using more resistance (>100k ohm) would lead to a dead travel knob at the end?! Of cause your start would be "secured" in a way that u cant go under a certain resistance and therefore under a certain current, so your COBs wont turn off if u dimm down to minimum but thats not a problem? ( you can get to a state where the COB gets warm and needs a higher voltage over time so he turns off because u were on lowest setting, cools down and needs lower voltage, so the COB turns on again and repeat. like a stroboscope. But thats no problem for the COB. the COB can handle PWM dimming with 10khz )
When i use a 100k ohm poti only ( in my spaceshipt its 5 CXB3590's ) i can dimm them from 10 - 100% until the last millimeter on the poti has been turned, no dead travel knob.
I really just want to understand, no harm or fight.
Jimmyclone
White Light Warrior
If you read your cob instructions it will tell you not too dim your cobs below a certain current as it can cause damage to the cob. That is why you install a resistor. It will always show a resistance to the driver and will not get you into this danger zone. The 50k pot is only if your dimming 2 drivers together from one pot.. 3 drivers =33k pot, 4 drivers together = 25k pot and so on. Also after checking over 20 pots at the electronics store only 3 tested a full 100k..most are in the low 90's.. So by adding the 10k resistor(if only dimming 1 driver) you guarantee your getting the full pull from the driver.. There is lots of info on this topic on RIU..
