Is it possible to create a LED driver for 8 – 10MM

Welcome, I too have been think to change out my cluster with LED’s.

When grabbing photos from Amazon I do a copy and paste to a photo editor and save to https://imgur.com/

Then use the direct link to this forum and you will see your photos.

Brightness for LEDs is controlling the current to the LEDs and yes the more current the brighter and the shorter the life.

I would play white some rheostat to see what you want, also look at the specifications of the LEDs to see the current draw.

Are the LEDs in series or parallel?
Have you look at this link?
https://www.nutsvolts.com/magazine/article/calculating_current#:~:text=When%20computing%20the%20value%20of,forward%20voltage%20of%20the%20LED.

@larry_n7luf Thanks for the info I don’t currently have a imgur account so yeah there’s that.   Im not sure how the Current VS voltage works on these LED’s i do know they are 1-3 VDC for them and i think the ones i was looking at for the 8mm ones are 20mah and the 10mm ones are the same.

Direct quote from the Amazon listings

“

• The working voltage of LED lamp is 3.0V, the working current is 20mah; The angle of luminous is 50°
• The Wattage of each lamp bead is 0.5W, and the wavelength range of each color: warm white 2900-3100k

“

Though i would of preferred 3500K or 3600K warm white LED’s but they are stupid hard to find.

Yeah i chose warm white as my Clusters have the Green filter caps in them because the blue light found in white light hurts my eyes ,  i have a 1974 VW transporter aka Bay Window Bus.

Welcome aboard! First off, what cluster are you making the switch or just in general? A PWM controller gives you the best light control for LEDs. I too have swapped my truck cluster out for LED and they don’t dim as they did stock because it is a variable voltage output. There is 2 of 3 pillar gauges that have internal controllers that dim correctly (PWM). I planned on doing something as you are asking about but haven’t worked on it. My plan however was to use the voltage signal from the BCM to control pulse width instead of a control (easy to do one or the other). At that point, the entire circuit would dim the same level and rate just isn’t high on my list.

@radtekman hello , so basically this is something that I have not done yet nor do I have anything in place to do yet.    My VW is all analog and no computer to control things so it just uses a rheostat to control the voltages supplied to the bulbs via 1 single wire for positive side , negative side ties to the chassis like one would expect.

I wanted to make housings for the diffused hobby LEDs then basically make plugs that slide over the pins on said LEDs then wire into a controller that would detect the incoming rheostat voltage then adjust the LEDs based on the brightness you set , maybe even have 2 potentiameters for min and max brightless. (Rheo stat calibration)  My VW has 2 circuits for high beam and low beam where I could tap into for controller power should I pull the knob out and then tap into the rheo stat wire for sensing.

My dash currently has 6 bulbs in them + the 2 down by my gear selector. (8 total+ Have room for more LEDs should I need them)  So I wanted to see if someone chat with me about the possibilities in creating a controller for LEDs for retro or vintage cars where you directly drop in modules without modifications to the original systems.

@radtekman I glad you pick this up and I will be following so I can work on mine.
I have a 1994 Honda that has a lot of bulbs that need to be replace.

“Mr Fox, first of all welcome to the forum. Secondly, referring to your question/suggestion it is very important to find out if the original LED circuitry of that cluster is actually a parallel LED row or a series LED row, or it could even be a mixed circuit as well. Another question is: does the cluster currently using a dimming circuit (IE: a variable pot or a current rheostat?) If there is such thing in place already is important to also know is the original lighting LED based or small incandescent lamps ? If they are incandescent then the dimming rheostat or pot or whatever that might be is doing the dimming by variable voltage means no current variation at all ! And if they are LEDs (originally) then the dimming pot/rheostat is then doing the dimming by variable current rather. So be careful. They are 2 different approaches al depending of what gives you the lighting (an LED or an Incandescent)

LEDs are current driven devices so by calculating a resistor in series with an LED according to the given voltage you can limit the current to the level stated in the datasheet of that LED. As reference a normal ordinary/standard LED takes in the ballpark of 10-15mA but beware, there are many other types of LEDs in fabrication today and the current can wildly vary between 2-3 mA up 20-30mA per LED . So it is important to know your LEDs well.

PWM is the easiest to work with when it comes to LED dimming. And what I have in mind is using a 555 timer IC. There are tons of schematics on the internet freely available that show you a dimming LED circuit for any configuration you might want. another very simple but crude way to do it is using a power mosfet or an LM317 regulator. they are both extremely simple circuits and you can fetch that circuit to experiment with in a matter of 5-10 minutes

@ovi4 incandescent , rheostat currently no LEDs and nothing digital.   It’s a 1974 vw transporter (VW Bay Window Bus) This is why a digital board needs to be created to drive LED’s   reason I want to do this vs getting replacement bulbs that fit the incandescent sockets is because it’s a pain to find warm white LEDs and also because the SMD’s found in them don’t spread the light good enough.

The LED’s I’m looking at are diffused hobby LED’s which are 20Mah.

@mrfox You also may have to make a diffuser for the LED’s as the LED’s are “directional” light sources, which means they emit light in a specific direction.

@mrfox The best way to find ideal LEDs is to go to the big name sellers such as DigiKey, Mouser, Farnell, RS components etc. and search specifically for diffused lighting LEDs as is they have to have a wider light spread and that is written in their specific datasheets by the angle at whish the lighting spreads usually look for LEDs that have specifically and angle higher than 110-120 degrees. If I remember correctly they can go up to 170 degrees (perhaps maybe more but I’m not entirely sure) they as a term of guidance if you open any basic (rock bottom cheap) solar garden light fitting they always use the most efficient widest lighting angle possible there. So if you have some just look at it and you’ll see what I mean. Those kinds of LED wont focus the light at all. They will simply deliver the light on all directions a lot more even than most of other LED types.

I had thoughts of how to set it up, but I do not know the specifics. The plan was to ask Mr. C his opinion of a solid design but I would prefer to experiment a little first. The concept is flexible enough to run on a voltage from my existing dimming circuit or have a standalone control as in the VW. Additionally, since I have no experience with circuit design (yes the videos help but still), I have not focused on that project among others.

@mrfox a nice and easy way to start experimenting with is pictured (below) considering that the starting point is 12v DC (the car battery) and the current demand per LED is a max of 20mA (as you’ve specified). The series resistor (currently 1.8K) can be re-calculated for a different current with the ohms law formula. You can start by breadboarding this very simple circuit and the MOS-FET doesn’t have to be the exact same one, you can choose a similar one that you might have. The 10K pot will give you the dimming and but putting a resistor in series with it you can choose a certain minimum amount of light as a starting point to dimming. Feel free to play with it and change values. Is fun !… 🙃 🙂 🙃 🙂 … 👍 

PS: please beware that playing with any circuit or modifying any car circuit can be dangerous since the car battery can deliver an insane amount of amperage that can melt any wires therefore whatever you choose to do, any circuit that you might make Must be Fused!!! (put an appropriate fuse in line with the + of your circuit) so in the event of the circuit failing you wont be burning your car to ground or even worst. your house (if the car is being parked in a garage that’s part of the house) So, please remember: Safety First!… 😶 

@larry_n7luf they mainly need to point in one direction and a little to the sides because the dials aren’t transparent on mine so it hasntonshine around the edge of the cluster faces . (A bad design if you ask me) But it’s an early design so.

@ovi4 my gauges aren’t transglucent so I think it would be a waste to have such a wide angle of light as most of it is going to get wasted by metal surround behind the cluster.