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chadbag

JNSF DIY lighting project (PCB based)

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gavino200
2 minutes ago, chadbag said:

 

Probably adhesed to the underside of the body shell roof.  I'll make as narrow as possible.

 

Agree. 

 

2 minutes ago, chadbag said:

 

I'd also like to use these in the longer european cars so want to make the last few LEDs on perforated sections that can be easily hacked off to shorten the boards.  Just wire a jumper across.

 

 

 

Euro compatible is also huge for me.

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chadbag
6 minutes ago, cteno4 said:

1206 are a lot easier to solder than 805s, the pads are bigger and easier to hold onto. Might try some tests on spacing and led numbers in some cars. Just solder up some 1206 along some buss wire at various spacing and numbers to play with.

 

@gavino200 Do you want to volunteer to test a few different LED spacings?  Or at least compare the TORM and Dani ones you've made to see if it makes any difference?

 

I kind of like 12-14mm as a compromise but not sure how that would work.

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gavino200
2 minutes ago, chadbag said:

 

All the sources say this is how you limit or eliminate the chance of a runaway led dying and leading to others dying through drawing too much current.

 

I've run LED ladders with individual resistors for a couple of years now with no problems. 

 

If one dies, I'll just open it up and replace it. I don't think the hassle to benefit ratio is favorable.

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chadbag
5 minutes ago, gavino200 said:

 

I wouldn't. I think that's overkill. It would be nice if this thing was quick and easy to set up. 

 

What do TORM and other third party boards do?

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gavino200
1 minute ago, chadbag said:

 

@gavino200 Do you want to volunteer to test a few different LED spacings?  Or at least compare the TORM and Dani ones you've made to see if it makes any difference?

 

I kind of like 12-14mm as a compromise but not sure how that would work.

 

Yeah, I can do that.  Both the measurements give (dani and TORM) work fine. Closer isn't necessary. If you want to see if wider is ok I could wire something up. 

 

I have to warn you that running LED testslike the one I did yesterday is not something that your eyes or brain will appreciate. Staring at those things yesterday gave me a massive headache. Just a heads up. 

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gavino200
4 minutes ago, chadbag said:

 

What do TORM and other third party boards do?

 

TORM don't do that. They have a pair of limiting resistors,  one on each circuit path. 

 

The Dani strips don't do that either. They have a single resistor on each tear out section. Nothing else.

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chadbag
1 minute ago, gavino200 said:

 

TORM don't do that. They have a pair of limiting resistors,  one on each circuit path. 

 

The Dani strips don't do that either. They have a single resistor on each tear out section. Nothing else.

 

What is the value on the Dani resister?    That is every 3 LEDs, right?  I am betting that is what this is.  They put one protective resister every 3.

 

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chadbag
8 minutes ago, gavino200 said:

 

I've run LED ladders with individual resistors for a couple of years now with no problems. 

 

If one dies, I'll just open it up and replace it. I don't think the hassle to benefit ratio is favorable.

 

Do you mean without individual resisters?   What you wrote is supporting putting them in.

 

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gavino200
Posted (edited)
28 minutes ago, cteno4 said:

1206 are a lot easier to solder than 805s, the pads are bigger and easier to hold onto. Might try some tests on spacing and led numbers in some cars. Just solder up some 1206 along some buss wire at various spacing and numbers to play with. Same with resistors, use the 805 as the 603 can be hard to handle. If you are making a lot of these make it easy on yourself and also for those that may not be as nimble! 

 

I agree strongly with this. I can solder 0805s with loupes on. But it's about as fun as sticking needles in my eyes. As a non-masochist I will not be doing that. There are probably no more than a handful of people on the forum who'd be comfortable using 0805s. I think we'll find the number of people comfortable with this project at all will be low. That's not a problem though.

 

 

Quote

 

Ceramics are tougher and lower profile. They can take spikes and also fail open, which won’t cause other issues with tripping dcc or melting other bits.

 

I agree. Ceramics are the way to go. I also don't give a rodent's behind about wasting a few components I've bought. I'm looking for a lifetime lighting solution.

 

Quote

 

best to test the circuit well before lots of pcb work and torture test it some.

 

Agree. Less haste. More speed.

 

Quote

 

also I think the capacitor inrush limiting resistor can be smaller, might test it.

 

 

 

Physical test. Yes.

Edited by gavino200

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gavino200
4 minutes ago, chadbag said:

 

What is the value on the Dani resister?    That is every 3 LEDs, right?  I am betting that is what this is.  They put one protective resister every 3.

 

 

Yes. One every 3 LEDs. I'm cosey on the couch now. I'll look at the value in a while. 

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gavino200
5 minutes ago, chadbag said:

 

Do you mean without individual resisters?   What you wrote is supporting putting them in.

 

 

Yes. Without. Typo.

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cteno4

 

21 minutes ago, chadbag said:

 

All the sources say this is how you limit or eliminate the chance of a runaway led dying and leading to others dying through drawing too much current.

 

This circuit with the dimmer resistor will be limiting your current to the parallel leds down to like 9ma so if one of the leds does end up overdrawing it should not be a run away. Worst it will would end up with one led on at 9ma (like half it’s 20ma rating) and the others just glowing. Frommwhat ive gleaned on doing these lighting circuits using a constant current driver if you are running at way below the rated currents of the leds the mismatch is not much of a problem. I assume it should work when using resistor as a current limiter ar way below rated limits. 

 

If you are going to put a limiting resistor on each led then you can just do away with the dimming resistor.

 

jeff

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gavino200

The Dani strips use 150 Ohm resistors. But that value is just what will protect them from being fried by 12V. It makes the LEDs shine like supernovas.

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cteno4

The led strips are modules of 3 resistors in series with a resistor to limit the current to 20ma thru the leds. The extra resistor added to the power you are supplying to the strips Just limits the current further to dim them down so they are not too strong innthe car with 6mleds.

 

on the ceramic caps you need to use 10v caps with the 5v circuit

 

i think a 5 or 10ohm resistor should be fine for the inrush limiter as it would stop things at a 1a, but best to use like 1/2w in a 1210 (which is easier to place and solder anyway). 100uf cap could have a momentary inrush of 6a, so there is a very brief high power period which I think resistors can handle the pulse load, but the beefier the resistor the better it will hold up innthe long run. 

 

jeff

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cteno4
1 hour ago, gavino200 said:

The Dani strips use 150 Ohm resistors. But that value is just what will protect them from being fried by 12V. It makes the LEDs shine like supernovas.

 

With each module having three 3.3v leds the resistor needs to drop 2.1v. If running full at 20ma then R = 2.1/0.02 = 105 Ohm. They use 150 to be safe on the strip.

 

jeff

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gavino200

I'm getting ready to order some components, but I wan't to make sure they'll be compatible with this project first. A few questions. 

 

1. Are you designing for inclusion of a full rectifier or two half diode bridges?

 

2. What's the size rectifier are you measuring from?  Do you have a link?

 

3. What size voltage regulator are you measuring from? Do yo have a link?

 

I'm going to buy a roll of 1206 ceramic caps. Likely 10V 22uF. Have you found any higher capacitance in 10V ceramic?

 

I'll also pick up some more 1206 LEDs In warm and bright.

 

I may buy a variety pack of 1206 resistors as well have to do some trial and error to find a suitable dimming resistance.

 

Probably I'll use AliExpress. It seems to be the cheapest. Is that also your experience?

 

 

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cteno4

for stuff like this aliexpress has been about the cheapest I’ve found. Look between vendors as some offer the faster shipping options cheap or free, some show up here in a week or so. Generally small packages from most of the aliexpress vendors come faster than from similar stuff from ebay vendors. Many vendors sell both places.

 

unfortunately ceramic top out at higher capacities at 16v, some at 25v but not many. Their charge density is not as high as tantalium, that’s why the smds at like 100uf and higher 25v are tantaliums. 

 

Cheers

 

jeff

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gavino200
18 minutes ago, cteno4 said:

 

unfortunately ceramic top out at higher capacities at 16v, some at 25v but not many. Their charge density is not as high as tantalium, that’s why the smds at like 100uf and higher 25v are tantaliums. 

 

 

Ah yes. I'm aware of this. That's why I'd like to use 15 or more. But with this kind of multiple a small increase over 22uF would add up to a lot. I did a fairly exhaustive search but couldn't find higher than 22. I'll probably search a bit more before committing to this.

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cteno4

At 10v you can get 100uf. Mouser says they are like $1.35 each and vendors on aliexpress are selling them at 50 for $3 so it’s a bit suspect these may be seconds... might get some and play.

 

did you try the 100uf before the dimmer in a car to see if it got rid of flicker? 

 

Jeff

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gavino200
16 minutes ago, cteno4 said:

 

did you try the 100uf before the dimmer in a car to see if it got rid of flicker? 

 

 

Nope. I ordered some but haven't received them. The only caps I have are 40V/220uF.

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cteno4

Sorry I thought those were 100uf my bad neurons.

 

there are 6.3v that you could use if you used a 3.3v regulator and I think it will be enough to light the leds. Might try the experiment. You need very low value resistor for the dimmer then as little voltage to be dropped just current limiting.

 

jeff

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chadbag
33 minutes ago, gavino200 said:

I'm getting ready to order some components, but I wan't to make sure they'll be compatible with this project first. A few questions. 

 

1. Are you designing for inclusion of a full rectifier or two half diode bridges?

 

Full rectifier.   Easier for my dumb brain.  The one you sent me a link on.  I've also ordered some other similar ones to try to see if we find something smaller.

 

33 minutes ago, gavino200 said:

 

2. What's the size rectifier are you measuring from?  Do you have a link?

 

Initially the L7805CV and similar (a few different current versions or manufacturers with the same or similar model numbers)  most of them are the TO-220 package.  I think they may be a bit large and have ordered a few lower current (but should be sufficient) other models that should be smaller.

 

One that is significantly smaller is that I ordered a small number of is:      LT1118CST-5

 

I also got a set of 5 of:  TA78L05F from Toshiba.  These are a lot more expensive and a little smaller (jyst rough comparison) to the LT1118CST

 

2.2uf and 1uf ceramic cap are needed on the input and outputs of the LT1118CST based on data sheet

0.33uF and 0.1uF ceramic caps are needed on the input and outputs of the L7805CV per the data sheet (and the TA78L05F)

 

33 minutes ago, gavino200 said:

 

3. What size voltage regulator are you measuring from? Do yo have a link?

 

I'm going to buy a roll of 1206 ceramic caps. Likely 10V 22uF. Have you found any higher capacitance in 10V ceramic?

 

I've ordered mainly 10u and 22uf in 1206 size.  I did find and ordered a set of 33uf.  Some of these may be 16V like the following

 

https://www.aliexpress.com/item/Free-shipping-1206-SMD-capacitor-47uf-16V-476M-100PCS/32375666910.html?spm=a2g0s.9042311.0.0.27424c4d9bKxsC

 

They also list a 47uf on that page (they have a list to choose from) which I will order some of.

 

33 minutes ago, gavino200 said:

 

I'll also pick up some more 1206 LEDs In warm and bright.

I got LEDs here.  robably similar prices from other vendors.  0.60 for 100

 

https://www.aliexpress.com/item/Smd-leds-led-smd-1206-bright-double/1297071940.html?spm=a2g0s.9042311.0.0.2f344c4dWUjBVV

 

 

33 minutes ago, gavino200 said:

 

I may buy a variety pack of 1206 resistors as well have to do some trial and error to find a suitable dimming resistance.

 

Probably I'll use AliExpress. It seems to be the cheapest. Is that also your experience?

 

 

 

I've used Aliexpress for most things.  Occasionally eBay and even some LEDs form Amazon.com (that came from China) as the price was similar and I got my 5% Chase Prime card rebate 🙂

 

 

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gavino200
1 minute ago, cteno4 said:

Sorry I thought those were 100uf my bad neurons.

 

there are 6.3v that you could use if you used a 3.3v regulator and I think it will be enough to light the leds. Might try the experiment. You need very low value resistor for the dimmer then as little voltage to be dropped just current limiting.

 

jeff

 

 

I think that's worth a try. Chad seems to be designing in that flexibility. Lower voltage widens the selection of cap considerably. I also think 5V is still very high. I use 5V as my standard for LEDs and I always have to drop it significantly.

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cteno4

It should work. I’ll paw around I think I may have some 3.3 regulators in the component box. 

 

I believe the caps and resistors used on the power regulators are more to make a robust power supply and tame inrush currents in the regulator. I think you may be able to do without them as you are not do a really sensitive circuit here.

 

jeff

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chadbag

One issue is that the warm white and bright white are usually listed as 3-3.3v

 

26 minutes ago, cteno4 said:

I believe the caps and resistors used on the power regulators are more to make a robust power supply and tame inrush currents in the regulator. I think you may be able to do without them as you are not do a really sensitive circuit here.

 

I'm going to find a website where I can get a critique of the circuit.  The data sheets mention that the typical use (and all the voltage regulators show similar) have an input and output cap so I want to get "expert" opinions on whether that is needed for what we are doing.

 

 

----

 

Based on specs, I am partial to the LT1118CST-5 voltage regulator as it is small and a lot cheaper than the toshiba (that I have found so far).

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