joelorigo
Well-known member
I bought a few of these boards recently, what value resistor and trim pot should I use?
3PDT Breakout Board with Brightness Control Parts?
- Thread starter joelorigo
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damianvila
Well-known member
For the resistor, you use the minimum for the led (maybe around 330R, but you can calculate it depending on the characteristics of the led). This will set the maximum brightness while keeping things safe. For the trim, I guess something not too big. Maybe 1 or 2K? Again, it depends on how low you want to go.
I don’t like to use these kind of solutions because trimpots are way more expensive than resistors, and it’s easy to try different resistor values with a led on a breadboard until you find a value that gives the amount of brightness you want. Set it and forget it. A trim is one more component you need to solder, to just adjust it once.
I don’t like to use these kind of solutions because trimpots are way more expensive than resistors, and it’s easy to try different resistor values with a led on a breadboard until you find a value that gives the amount of brightness you want. Set it and forget it. A trim is one more component you need to solder, to just adjust it once.
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Betty Wont
Well-known member
I’d go 1k on the clr, and 20k for the trim. I use clear red leds with 10k as standard. That set up would go from blinding to dashboard dim.
damianvila
Well-known member
Oh, yeah… clear ones…
I never use those. If you catch them straight on at maximum brightness… cor blimey!
joelorigo
Well-known member
In this pedal I will be using this:
The lowest value trimmers I currently have are 5k and 10k.
Also, I don't mind a bright LED!
The lowest value trimmers I currently have are 5k and 10k.
Also, I don't mind a bright LED!
damianvila
Well-known member
For that one I get 300R as clr from the calculator.In this pedal I will be using this:
The lowest value trimmers I currently have are 5k and 10k.
Also, I don't mind a bright LED!
Basically (9V-3.2V)/0.02A=290R (300R is the closest)
9V is the circuit voltage, 3.2V is the Fv of the led (indicated in the page), and 0.02A (20mA) is the led current (also indicated in the page).
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joelorigo
Well-known member
Good point. Actually I think I meant to buy the ones that don't have a trimmer / resistor. Is there a way to skip using the trimmer by jumping some of the trimmer pads?
damianvila
Well-known member
Yes, there surely is. I guess the CLR is in series to get a minimum value, so you probably need to bridge the leg connected to the CLR and the one connected to the led (check with a multimeter in continuity).
Bricksnbeatles
Member known well
I do 1k resistor and 10k trimmer for a lot of them. There are a handful of LEDs that I’ll do 680, but still a 10k trimmer.
Robert
Reverse Engineer
joelorigo
Well-known member
I am building this now, jumped the trimmer pads as indicated above. I currently have 240R and 470R for the resistor. What would be the effect of a lower and higher value? I assume one will be a brighter LED, the other less?
spi
Well-known member
I use the $0.06 ones for this. Yeah, they're 4x more expensive than resistors but not really breaking the bank.
10K OHM Trimpot Variable Resistor 6mm (taydaelectronics.com)
Feral Feline
Well-known member
If I was only going to have a fixed-CLR, I would hand-wire the switch (or get the correct daughterboard) and save the dimmable daughterboard for a build that I wanted the adjustable option.
I know the daughterboards are the same price (dimmable or fixed, they're a buck apiece), but that's just me.
I know the daughterboards are the same price (dimmable or fixed, they're a buck apiece), but that's just me.
damianvila
Well-known member
290R is peak brightness, so 240R will stress the led, and make it last less than it should. 470R will make it dimmer, but if the led is bright, it won’t matter much.
Where will you be using this pedal? If you play outside on a sunny day, you may want to use something near peak brightness, to be able to see the led. But if you’re using the pedal indoors at home, or in dark places, and the led is bright, you may want to use a higher resistor, to tame the led a bit, since it may dazzle you in those settings. Maybe use something in the 1.5k-2k range.
To test the brightness you can use a 9v battery, twist the resistor to one leg and connect the resistor and the other leg to the battery. Or use a breadboard.
joelorigo
Well-known member
Thanks for this info. Most of the time I will be in the garage by myself.
I will do the test with a battery with what I have. Alternatively / additionally there is a place here in town that I could probably pick up 300R.
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