Adding Lights to your interior...w/fading option

[Nismode]

I've searched to no avail. Basically, I've seen pictures of members adding these lights bars (from threads like these) to their footwells, trunk, license plates, etc. I've even seen someone try to wire their map lights to the ceiling lights (like this old thread).

What I'm trying to find out is if it is possible to wire these additional lights to the dome light that fades in/out on lock/door close.

For example, to have the light tubes in the footwell turn on with the dome light when the door is opened, and fade back off when it is closed. And if wiring the map lights to the ceiling lights is also possible.

 

[finch13]

I don't think you could add much to that circuit before overloading it, so I'd recommend using a relay. I have no idea how you could get a relayed circuit to fade though.

 

[Nismode]

I don't think you could add much to that circuit before overloading it, so I'd recommend using a relay. I have no idea how you could get a relayed circuit to fade though.

It has been done in OEM applications I know (BMW's interiors, the footwell lights fade out with the dome/rear lights).

And which circuit are you talking about specifically? The entire circuit? Or where most people wire the footwell and other additional lights (which would be where)?

 

[finch13]

It has been done in OEM applications I know (BMW's interiors, the footwell lights fade out with the dome/rear lights).

And which circuit are you talking about specifically? The entire circuit? Or where most people wire the footwell and other additional lights (which would be where)?

Oh I know it can be done. What I'm saying is, if you add a ton of LEDs to the circuit, you may overload it, burn wires and fuses, etc. All the lights that currently fade out are on one circuit (assuming) and that circuit was designed to only supply those lights, adding more doesn't help the circuit. Whereas, an OEM application, the circuit was designed to fade the foot lights and door lights and dome lights, so the circuit was properly sized.

Adding a relay would make your new lights appear to be on the same circuit, but in reality they would be on a completely different circuit, but controlled by the same device.

Only thing I don't know is how you could fade them, a relay is either on or off. You would have to be able to hold the relay circuit closed, fade it, and then break the circuit.

Most people connect their lights to the power outlets wiring. Yes, it's easy to do, but in theory is stupid. In my opinion, it's the lazy man's way of tapping into power. Grabbing power where the batery connect to the engine bay fuse box is your best bet and keeps things clean, not to mention it keeps the new wiring and the existing wiring from interfering with each other.

 

[Nismode]

Hmm ok. Makes sense. So there's no type of relay or other connection that would be able to gradually reduce power to a device to allow it to fade?

 

[finch13]

Hmm ok. Makes sense. So there's no type of relay or other connection that would be able to gradually reduce power to a device to allow it to fade?

No, there has to be. It may involve making your own circuit board and doing some soldering, but it's possible.

 

[Nismode]

No, there has to be. It may involve making your own circuit board and doing some soldering, but it's possible.

Ha, something I don't have any experience in. Thanks, I'll keep looking around though, hopefully someone who has a bit more electrical know-how than me can give some input on this as well.

 

[finch13]

All credit goes to Bill Bowden, his website can be found here.

Fading Red Eyes

Circuit description:

This circuit is used to slowly illuminate and fade a pair of red
LEDs (light emitting diodes). The fading LEDs could be installed
as 'eyes' in a small pumpkin or skull as a Halloween attraction,
or mounted in a Christmas tree ornament. Or, they might be used
as a fancy power indicator for your computer, microwave oven,
stereo system, TV, or other appliance.

In operation, a linear 3 volt (peak to peak) ramping waveform is
generated at pin 1 of the LM1458 IC and buffered with an emitter follower
transistor stage. The 22uF capacitor and 47K resistor connected to
pin 2 establish the frequency which is about 0.5 Hz. You can make the
rate adjustable by using a 100K potentiometer in place of the 47K
resistor at pin 2.

The circuit consists of two operational amplifiers (opamps),
one producing a slow rising and falling voltage from about 3 volts to
6 volts, and the other (on the right) is used as a voltage comparator,
the output of which supplies a alternating voltage switching between
2 and 7 volts to charge and discharge the capacitor with a constant
current.

Each of the op-amps has one of the inputs (pins 3 and 6) tied to a
fixed voltage established by two 47K resistors so that the reference
is half the supply voltage or 4.5 volts. The left opamp is connected
as an inverting amplifier with a capacitor placed between the output
(pin 1) and the inverting input (pin 2). The right opamp is connected
as a voltage comparator so that the output on pin 7 will be low when
the input is below the reference and high when the input is higher
than the reference. A 100K resistor is connected between the comparator
output and input to provide positive feedback and pulls the input
above or below the switching point when the threshold is reached.
When the comparator output changes at pin 7, the direction of the
current changes through the capacitor which in turn causes the inverting
opamp to move in the opposite direction. This yields a linear ramping
waveform or triangle waveform at pin 1 of the inverting opamp.
It is always moving slowly up or down, so that the voltage on the
non-inverting input stays constant at 4.5 volts.

Adjustments to the point where the LEDs extinguish can be made
by altering the resistor value at pin 3 and 6 to ground. I found
a 56K in place of the 47k shown worked a little better with the
particular LEDs used. You can experiment with this value to get
the desired effect.


Parts List:

Description Mfg Part# Allied Part# Quantity Cost

Operational Amplifier LM1458 288-1090 1 .48
47K Resistor 296-2182 4 .42
100K Resistor 296-5610 1
100 Ohm Resistor 895-0465 1 .24
Transistor 2N3904 568-8253 1 .1
22uF Capacitor 852-6516 1 .07
Solderless Breadboard 237-0015 1 6.99
Red Light Emitting Diode (LED) 670-1224 2 0.50

Note: The LED listed has a narrow viewing angle of 30 degrees and
appears brightest when looking directly at it. It's not a pure red
color, and a little on the orange side, but should be brighter
compared to other selections. For a wider viewing angle at reduced
intensity, try part number 670-1257 which is viewable at 60 degrees
and has a red diffused lens.

Construction details:

Layout of the solderless breadboard:

Refer to the drawing below the schematic diagram and note the
solderless breadboard is arranged in rows labeled A-J, and
columns numbered 1 to 65. Each group of 5 holes in the same column
are the same connection, so that holes A1,B1,C1,D1 and E1 are all
connected together. Likewise holes F1,G1,H1,I1 and J1 are all
the same connection. The outer rows along the length of the
board are also connected together and are normally used for
power supply connections. However, there is a break in the
mid section of the outer rows, so a short jumper wire connecting
the mid section of the outer rows should be installed to connect
the entire outer row together. If you have a DMM, use the low
ohms range and probe the various holes to get familiar with the
board layout.

Installing the components:

Orientate the LM1458 so the nook or punch mark on one edge
is near column 30 and the opposite edge is near column 33.
Install the LM1458 on the breadboard so the pins straddle
the center section of the board and pin 1 of the IC is occupying
hole E30 and pin 8 is in hole F30. The pins are numbered counter
clockwise, so pin 4 will be occupying F33 and pin 5 will be in E33.
Possible connections for the LM1458, 9 volt battery, and a couple
other parts is illustrated in the lower drawing of the solderless
breadboard, but it is not complete with all parts.

Refer to the schematic diagram, and install the various other
components so they connect to the appropriate pins of the
LM1458. Use whatever connection holes are convenient.
For example, the 22uF capacitor connects between pins 1 and 2
of the IC, which occupy holes (F30,F31) so it could be placed
in the holes (H30, H31) or (J30,J31) or (I30,I31). But not all parts
will conveniently fit, so you may have to use a short jumper
wire (#22 preferred) to connect parts from one side of the chip
to the other.

The board I assembled was connected this way:

LM1458 F30 to F33, and E30 to E33
22uF capacitor H30 to H31
47K resistor I30 to I35
47K resistor C27 to C31
47K resistor F25 to Positive battery row
47K resistor J25 to Negative Battery row
100K resistor B31 to B33
2N3904 Transistor G36, G37, G38 with emitter at G38
100 Ohm resistor D38 to F38
LED B43 to B44 (Cathode at B44)
LED I43 to I44 (Cathode at I43)
Jumper A30 to Positive battery row
Jumper F36 to Positive battery row
Jumper J33 to Negative battery row
Jumper J43 to Negative battery row
Jumper H25 to J32
Jumper J30 to J37
Jumper E27 to G31
Jumper D32 to G32
Jumper D33 to H35
Jumper C38 to C43
Jumper E44 to F44
9 Volt Battery Postive battery row to negative row.

The circuit below illustrates two pairs of LEDs that operate out of phase so as one pair slowly illuminate, the other pair will fade.

 

[Nismode]

Wow, great find man! (Added rep)

I wish I could understand this diagram a bit more though. I'm gonna take a look at it with a few EE buddies of mine. This looks like it fades in and out based on the frequency of the resistor/potentiometer. So I'd have to find a way (or possibly just email this guy) to not make it adjustable, just have it fade when powering down the LED's.

Further down the page looks like what I'm talking about:

Automobile Interior Lights Fader

This circuit is similar to the fading eyes circuit above and is used to slowly brighten and fade interior lights of older cars.

The circuit is based around the LM324 low power opamp which draws around 3mA of current, so it won't bother the battery if left connected for extended periods.

The top two opamps (pins 1,2,3 and 5,6,7) form a triangle wave oscillator running at about 700Hz while the lower opamp (pins 8,9,10) produces a linear, 5 second ramp, that moves up or down depending on the position of the door switch. The two transistors and associated resistors serve to limit the ramp voltage to slightly more and less than the upper and lower limits of the triangle waveform. These two signals (700 hZ. triangle wave and 5 second ramp) are applied to the inputs of the 4th opamp (pins 12,13,14) that serves as a voltage comparator and generates a varying duty cycle square wave that controls the IRFZ44 MOSFET and lamp brightness. The 5 second fade time can be adjusted with the 75K resistor connected to the door switch. A larger value will increase the time and a smaller value will speed it up.

When the door switch is closed (car door open) the voltage on pin 8 slowly rises above the negative peaks of the triangle wave producing a short duty cycle output and a dim light. As the ramp moves farther positive, a greater percentage of the triangle wave will be lower than the ramp voltage producing a wider pulse and brighter light. This process continues until the ramp is 100% above the positive peaks of the triangle wave and the output is maximum. When the door switch is open, the reverse action takes place and the lamps slowly fade out.

The IRFZ44 shouldn't require a heat sink if the total load is 50 watts or less but the temperature of the MOSFET should be monitored to insure it doesn't overheat. The on-state resistance is only 0.028 ohms so that 4 amps of current (48 watts) is only around 100mW. For larger loads, a small heat sink can be added to keep the MOSFET cool.

 

[finch13]

LOL, that's awesome. I can't believe I missed that one! Yeah, I don't get into electronics this deep, but it would be interesting to do.