led taillight delima...help

[DirtyLude]

You can braze aluminum. It's exactly the same thing as soldering, but it's at a higher temperature.

There are specific alloys used in brazing aluminum and it's not easy either, because the melting temp of the braze and the base metal are pretty close.

Anyway, it's probably something you want someone experienced to do. Otherwise, just rivet it together.

You can try something like these brazes https://durafix.com/ I hear they can be quite brittle, though. Shouldn't be a problemwith a non structural item, like a base for a light.

 

[airbrush]

alright..thx...just thought i'd ask...guess i'll have to use a different way

 

[airbrush]

does anyone know of any tutorials or schematics for this...

3) A low-power dimmer is a circuit you would have to make. It uses an IC and a small "volume control". Some ordinary lamp dimmers turn off completely. But when you slowly turn them up from being off, they suddenly jump to 1/2 brightness.

 

[panic mode]

you can solder aluminum but it's very difficult...
to do this aluminum surface that is to be soldered must be submerged into
oil (no contact with air), already oxdized surface need to be sanded and coated with solder - all while submerged (preventing contact with air).

after that, you can clean it and finish soldering even in air because layer
of solder (applied while piece was under oil) is going to keep it from
contact with air.


about the lamp... i don't think you can make any circuit for this that will be significantly smaller than small transformer. if you don't like it at the wall, include in the base of the lamp where your "volume" knob is going to be and use simple PWM with 555 or whatever.
20LEDs x 3V x 5mA = 300mW (colegue just bought some high efficiency super bright white ones).
if you connect them in groups of 4 LED and resistor in series and then
all five such groups in parallel this can be driven by 555 output directly
and powered by tiny wallwart. 555 and all parts can be SMT and mounted on the back of potentiometer.

 

[airbrush]

okay...so an adapter is best then...i hate those big bricks though, does anyone know a source of small ones? if there is such a thing.

If anyone out there could provide a layout and explantion of how this dimmer switch goes together i can start experimenting with getting it working...much appreciated as always from the newbie . Photos are always good too.

also what kind of potentiometer to use...looking at my local suppliers site, they have 1/2 watt 5k,10k,50k,100k,500k

so i can use just normal lamp cord/wiring to go from the adapter to the switch then??

thanks

 

[airbrush]

....also i want to have one or more rows of leds each with its own dimmer.

 

[panic mode]

i don't know why d you think that a wallwart has to be size of a brick...
they can be quite small. any PWM circuit will do. you can have multiple ones. check NE558. it is one chip with four 555s in it. just google for
something like "555 pwm"....

**broken link removed**

 

[airbrush]

obviously i am exagerating a little...i just dont like the look of these bulky boxes when they are somewhere you can see them...an inline one might be okay.
If anyone knows of a good source tutorial for newbie and some schematic or photos that would be great.

 

[David Bridgen]

Airbrush, just in case you don't notice, I have sent you a PM.

 

[David Bridgen]

If anyone out there could provide a layout and explantion of how this dimmer switch goes together i can start experimenting with getting it working...much appreciated as always from the newbie . Photos are always good too.

also what kind of potentiometer to use...looking at my local suppliers site, they have 1/2 watt 5k,10k,50k,100k,500k
thanks

I would love to provide a solution but unfortunately I am departing on Wednesday for the 'States and will be there for some weeks and I won't have time before I go.

My access to a pc will be limited to an occasional hour in the local public library so that is unlikely to be sufficient time - after checking email and ditching all the junk etc etc. I don't know if they have Paint installed either.

If you haven't got an acceptable design by the time I get back I shall see what I can cook up.

 

[airbrush]

found this after some searching...

**broken link removed**

shows a few different setups...not sure which i should go with...probably the third setup, but i am not sure how this hooks up to the potentiometer...i will probably be running a few dozen leds.

 

[David Bridgen]

The link doesn't work. Can you check it?

 

[airbrush]

there we go....all workin now

 

[audioguru]

Hi Airbrush,
The 2nd circuit might work well for brightness control of its 3 LEDs. It would probably have a greater range of dimming if it had 2 diodes. A linear 1M pot would have most of its dimming crammed at one end, a logarithmic (audio taper) pot would match the log response of our vision.

I would add a very important capacitor across its supply. Of course, 3 LEDs in series won't work if they are 3.5V each and the supply is only 9V.

The author must be rich or crazy to use a separate Mosfet for each set of 3 LEDs in the 3rd circuit. A single Mosfet can drive hundreds of LEDs. See my mods attached:

 

[airbrush]

hmm...okay..wonder why he says it can drive a dozen or more leds then?

So i can just keep adding on leds with this layout? is there a limit to how many i can string up? Where is the potentiometer represented in this layout....where do i hook it up to?

so which of these can i use for this application? i was hoping to use a slider, but a rotary will do if i have to...https://www.futurlec.com/Potentiometers.shtml

or do you know another source where i can get what i need?

 

[audioguru]

hmm...okay..wonder why he says it can drive a dozen or more leds then?

Because he contradicts himself.

So i can just keep adding on leds with this layout? is there a limit to how many i can string up?

The limit of LEDs for a Mosfet to drive is determined by the LED current that you use and the current and power rating of the Mosfet you use.

Where is the potentiometer represented in this layout....where do i hook it up to?

The pot is shown clearly on the schematic. If you don't see it, maybe you should get an experienced person to build the project.

so which of these can i use for this application? i was hoping to use a slider, but a rotary will do if i have to...https://www.futurlec.com/Potentiometers.shtml

Sorry, I didn't look because you didn't have a space ahead of your link.
Use a 1M, logarithmic (audio taper) pot.

or do you know another source where i can get what i need?

There are many places to buy electronic parts. I shop online at www.newarkinone.com and www.digikey.com . Newark is known worldwide as Farnell.

 

[airbrush]

The pot is shown clearly on the schematic. If you don't see it, maybe you should get an experienced person to build the project.

right right...the resistor symbol with the arrow beside...like i said, i'm a newbie and hey..you gotta learn somehow right. :wink:

thx for the links...i'll check em out.

Okay this looks like a pretty good setup to get me rollin.

Do you know if this would generate a lot of heat? i would like to have three setups like this contained within a base for a lamp each controlling a different set of leds.

 

[audioguru]

Not much heat. The transformer or wall-wart will get the hottest.

 

[airbrush]

does the potentiometer have to be 1M? what determines this?

what if i want to use a slide potentiometer...the highest i found was 100k, how would i make that work with this? or a potentiometer with a lower rating?

 

[audioguru]

Hi Airbrush,
A 1M pot allows the circuit to dim 1000 to 1, which is OK but not fully off. A 100K pot would dim only 100 to 1, which is noticeably dim, but still fairly bright.

The only other rating of a pot is its power rating. Either pot in this circuit dissipate almost no power.