12v lamp dimmer

[Qwerty]

I am looking for a circuit that I can take 2 different 12v inputs as a selector with a single output to an incandecant lamp, one
input would output a reduced voltage to the lamp (say 60%) and the other input when active would cause the lamp to light a
100% of it intensity. A bit of a delay (say 1-2 sec) when switching back to 60% intensity would also be nice.

Any thoughts, suggestions, diagrams???

Thanks for any help.
Tim

 

[Tops]

I am looking for a circuit that I can take 2 different 12v inputs as a
selector with a single output to an incandecant lamp, one
input would output a reduced voltage to the lamp (say 60%) and the other
input when active would cause the lamp to light a
100% of it intensity. A bit of a delay (say 1-2 sec) when switching back
to 60% intensity would also be nice.

Any thoughts, suggestions, diagrams???

Thanks for any help.
Tim

If the circuit is AC the energy to the bulb on one circuit could be reduced
significantly by putting a diode in the circuit to eliminate one half of the
AC waveform. Cheap and simple

 

[Phil Allison]

"Tops"

If the circuit is AC the energy to the bulb on one circuit could be
reduced significantly by putting a diode in the circuit to eliminate one
half of the AC waveform. Cheap and simple

** The stepdown transformer would be very unhappy about the load with a
diode in series.

It will growl and overheat - especially if a toroidal type.




........... Phil

 

[John Crighton]

I am looking for a circuit that I can take 2 different 12v inputs as a selector with a single output to an incandecant lamp, one
input would output a reduced voltage to the lamp (say 60%) and the other input when active would cause the lamp to light a
100% of it intensity. A bit of a delay (say 1-2 sec) when switching back to 60% intensity would also be nice.

Any thoughts, suggestions, diagrams???

Thanks for any help.
Tim

Hello Tim,
have a look at this article.
I think it will do what you want
with a modification or two.
http://www.solorb.com/elect/solarcirc/pwm1/

For two fixed lamp brilliance settings
you could make VR1 a normal fixed resistor
and use a change over switch to select the
top end or bottom end of this new resistor.

Or you could make a second voltage divider
R6 VR1 R7
and use a change over switch to select either
one wiper or the other wiper.

To get the slow change in lamp intensity
after switching, you could fit a resistor between
the wiper of VR1 and Pin 6 of U1b along with
an electrolytic cap on Pin 6 to Ground.
Experiment with different values to get the
desired delay in lamp intensity change.

Regards,
John Crighton
Hornsby

 

[Tops]

"Tops"


** The stepdown transformer would be very unhappy about the load with a
diode in series.

It will growl and overheat - especially if a toroidal type.




.......... Phil

What would be the best way to do this Phil while keeping the cost as low as
practical.
P_R.

 

[Phil Allison]

"Tops"

"Phil Allison"
What would be the best way to do this Phil while keeping the cost as low
as practical.
P_R.

** You did not answer my point - fuckhead.

The OP has not specified the details his actual problem - not that a lying,
know nothing criminal scumbag from Maitland like you would notice.




......... Phil

 

[Tops]

"Tops"



** You did not answer my point - fuckhead.

The OP has not specified the details his actual problem - not that a
lying, know nothing criminal scumbag from Maitland like you would notice.




........ Phil

Phil, all I can say to your unprovoked outburst is..you certainly have a
very significant problem.

 

[Phil Allison]

"Tops"

"Phil Allison"
Phil, all I can say to your unprovoked outburst is..you certainly have a
very significant problem.

** Like fucking hell it was "unprovoked".

Piss off - you steaming pile of criminal libelling scum.



NB This arsehole is known to me from another NG.



.......... Phil

 

[Tops]

"Tops"



** Like fucking hell it was "unprovoked".

Piss off - you steaming pile of criminal libelling scum.



NB This arsehole is known to me from another NG.



......... Phil

Gee, we really are belligerent tonight, aren't we Phil. Totally unrestrained
with the vitriol as per usual.

 

[Tops]

"Tops"



** You did not answer my point - fuckhead.

The OP has not specified the details his actual problem - not that a
lying, know nothing criminal scumbag from Maitland like you would notice.




........ Phil

What is your point, Phil. You could be giving a constructive answer to the
original poster's issue instead of going on like a pork chop.

 

[Phil Allison]

Gee, we really are belligerent tonight, aren't we Phil. Totally
unrestrained with the vitriol as per usual.

** Drop dead.

 

[Qwerty]

Thank for you for the link, I will check it out.

To answer some questions:
unregulated - will vary from approx 11.5-14.5v
DC operation
both inputs are from the same source but connected to 2 different switches:
- one switch most likely always on will be at the reduced intensity
- 2nd switch will only activate as needed and provide 100% intensity.
- 2nd switch is connected to a flasher circuit, hence the delay as I would like the lamp to turn off between flashes for more visual impact.

thanks again for the quick replies.
Tim