Light dimmer

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

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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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     /__/  /    \      ** Registrovani korisnik Linuksa #291606 **
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Reply to
Yvan
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Uh, why not do what GM has always done? A relay and a diode...

Reply to
PeterD

I just feed a relay to the head lights, They last just as long. Works great, people still cut me off.

Cheers

Reply to
Martin Riddle

Nedavno Martin Riddle napisa:

I already did that, I just wanted to use high beams at, say 50-60% as drl's as BMW factory solution for E36.

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Reply to
Yvan

The MOSFET needs to have several volts between its gate and source to be turned on. If you put the head light in the source leg you need to run the 555 on a higher voltage or the MOSFET won't see the needed gate drive and there will be a large loss in it.

You have several options.

(1) Use a P-channel MOSFET. The source would go to the +12V and the drain to the light.

(2) Use a PNP transistor for each head light. The drain of the MOSFET would drive the base connections through a hefty resistor.

(3) See that the law allows you to drive the car as it was made and leave it alone.

Reply to
MooseFET

ANY design with the notation "555" in it, by definition, sucks.

Use a PIC!

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Many thanks,

Don Lancaster                          voice phone: (928)428-4073
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Reply to
Don Lancaster

You sound like Slowman.

Ick.

Reply to
krw

Don Lancaster is another one who's living in his own past... much like Billy Bob Slobman :-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Nedavno MooseFET napisa:

Like this?

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I now have low beams as drl's (switched on with ignition via unloader relay). But I would like to use high beams (BMW factory solution for E36).

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Reply to
Yvan

What do the regulations dictate?

Would it suffice to use relays to series the two high beams? ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

cd4538 works well.

Oh and I checked the local library for those Modern Electronics. No dice, they have everything else tho.

Cheers

Reply to
Martin Riddle

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

I think GM use to use that technique on their trucks, now its just one light.

Cheers

Reply to
Martin Riddle

You'd need a p-channel fet.

A 60 watt, 12-volt lamp may pull 50 amps at turnon, enough to fry the fet. I'd use a big power resistor and no electronics.

BUZ60 is the wrong sort of fet anyhow. It's rated at 400 volts, 1 ohm Ron.

John

Reply to
John Larkin

o

You have the MOSFET sources wired to the bulbs. This is not going to work.

T

#291606 **

Reply to
MooseFET

This should work

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May survive even a load-dump.

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Muzaffer Kal

DSPIA INC.
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Reply to
Muzaffer Kal

Nedavno Jim Thompson napisa:

Probably, but both light bulbs are grounded at the headlight, so I think that I can not do what you are suggesting.

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Reply to
Yvan

What requirements are dictated by the law? Brightness? ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

Nedavno MooseFET napisa:

What about this:

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Reply to
Yvan

Cool. 96 amps, if you don't use the leads. IR has even higher current fets, if you don't use the leads.

But 300 watts in a DPAK?

John

Reply to
John Larkin

Nedavno Muzaffer Kal napisa:

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Not available here, not economical to order from digikey.com

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Reply to
Yvan

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