Light dimmer

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I want to make light dimmer for my car to use as daytime running lights
(now required here by law), and I found this:


http://www.electronics-tutorials.com/devices/555-light-dimmer.htm

What do you think about this design?

Each headlight bulb is fused separately, and both are grounded at the
headlight housing. So I need to do some modifications to the circuit.
Can I just add another power mosfet, and connect it to the pin 3 of 555
(to the same pin as existing one)?

And, since both H1 headlight bulbs are grounded I have can I just
connect +12V to the pin 2 at the mosfet, and put the bulb between the
pin 3 and ground? Or do I have to use different mosfet?

BTW I couldn't find MTP3055E locally, so I bought BUZ60.

As you can see I am electronics newbie, so go easy on me :-)

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Re: Light dimmer


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Which part of the world is it that mandates drl's
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Re: Light dimmer


Nedavno F Murtz napisa:

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Serbia. All vehicles must have drl's or dipped beams on from 01.01.2010.


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Why complicate things. You can buy a pair of high intensity LED
automotive lights for a small price.

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Registered Linux user # 468070

Re: Light dimmer


Nedavno qmod napisa:

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Even simpler. I connected low beams via unloader relay, but wehere is
the fun in it?

I want to use high beams at ~50% intensity as drl's. And I want to keep
the original look of my BMW without additional bumper mounted lamps.

What would be ideal is dual H1 bulb, similar to the 21/10W bulbs that
are used as tail / brake light at the back. I think that new VW Golf
has it, its 55W/19W, but it is not H1. Does something like that exist?

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Nedavno Yvan napisa:

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Here is H15 60/19w:

http://img.photobucket.com/albums/v237/gerardleesgp/Golf%20VI/P24-03-09_092201.jpg

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If you could insulate one of the sockets from ground you could use a
DPDT relay (or a pair of DPSTs) to switch between series and parallel
connection of the lamps.

if the two adjusting screws go into plastic inserts you may only need
to insulate the remaining mounting screws, perhaps using the plastic
bushings from a TO3 transistor mounting kit, perhaps using automotive
body putty.


Re: Light dimmer


Nedavno Jasen Betts napisa:

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It is cold here, and I was looking for something to do inside the
house :-)



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Why is Serbia so far behind the times.
Most other countries have worked out statistically they do nothing
except waste fuel.

Re: Light dimmer


Nedavno F Murtz napisa:

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Because of corruption at all levels, "experts" that have no idea what
they are doing... Unfortunately I can go on for a long time here...

There was a lot of misleading information on TV, newspapers, and even
the new regulations started on December 10th there are still unfinished
parts, so noone knows what to do.

Someone probably copied regulations from some EU country from few years
back.

Sadly everything is aimed at the average driver, but if, for example,
you hit a pat hole and damage your car, it is your fault, you were
driving to fast. You can take responsable company to the court, but
that is few years long ordeal that you do not want to go trough.

But this is not the NG for this...

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yes, for that setup you need to use a P channel mosfet like IRF9540N
(avail from jaycar) the brightness control will then work in the
opposite direction, but that can be corrected by reversing the
connections to it.

NE555 is not designed for automotive applications. it will probably
not survive a load dump.



Re: Light dimmer


Nedavno Jasen Betts napisa:

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Like this:

http://www.ptt.rs/korisnici/i/v/ivica/carb/DRL.jpg


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Can you explain this a bit further? What do I need to change? Ad one
LM7812?



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7812 is good to about 40V input. load dump can go over 100V
so no, also 7812 is a positive regulator, and to drive mosfets
you want to be conected directly to their drain terminal and a 7812
would ruin that, a 7912 would work but still 40V would kill it.

perhaps something like this:


 "+12"------------------+---------------- to 555 pin 8
                        |
                       _|_/
                      // \
                       -+- 15V zener
                        |
           +--[1K]------+
           |            |B
           |          --+== MJE350  
           |          /  |\
 ground ---+-|<------'     `------------- to 555 pin 1
                     C     E
           1n4004

It might need to be modified to also pull the 555 reset
low when a current flows throut the zener thus protecting
the MOSFETS from over voltage by turning them on.

while adding that, a circuit to turn off the mosfets when the input
voltage goes below 12V is potentially a money saver too.



Re: Light dimmer


OK, thank you.

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Re: Light dimmer


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You could just use your low beam. The amount of power you save is
actually minuscule and will probably never pay for the electronics.

A BUZ60 should work fine as a substitute for the MTP3055E. To protect
the 555 you will need at least a resistor and 15v zenner diode. A 7812
might not work so well - it will need the same type of protection as the
555.

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