Voltage output over time....

[Paul Aspinall]

Hi
I have an application which I want to use 'dimmable' lights.....

I have the light components, but the actual dimmer has a 10 volt reference
voltage, ie.
0volts = 100% light
10volts = 0% light

I know I can add a pot, so I can regulate the voltage. However, I would like
to have a device which will change this voltage for me, over time (ie. going
from 0 to 10v over 1 minute, 1 hour, etc etc), so that I can vary the light,
and how quickly it dims.

Does anyone know how this can be done??

Thanks

 

[Michael Shaw]

Hello,

This sounds like a job for a good old 555 timer IC.

Try downloading a datasheet for this IC.

 

[Alexander]

Analog or Digital

Analog: use a 555 (or two) and selectable RC time constants.

Digitally: use a counter, (or counters), a slow clock, and a DAC

If you really want to get fancy use a micro; a bit of over kill.

You're using both ways (digitally and analog) PWM.
Perhaps you should look into that also.

 

[Henry]

Hi
I have an application which I want to use 'dimmable' lights.....

I have the light components, but the actual dimmer has a 10 volt reference
voltage, ie.
0volts = 100% light
10volts = 0% light

I know I can add a pot, so I can regulate the voltage. However, I would like
to have a device which will change this voltage for me, over time (ie. going
from 0 to 10v over 1 minute, 1 hour, etc etc), so that I can vary the light,
and how quickly it dims.

Does anyone know how this can be done??

Thanks

After dabbling again with some electronics (after about 20 years), I have
rediscovered just how versatile these littel 555 (556 for dual package) are.
I am certain that I have seen a light fader circuit somewhere. I think it
took two 555s (single 556).

Henry

 

[[email protected]]

Do you want a schematic, or a pre-built solution?

You can simply buy a controller card, and program your PC to do this.
This is the most flexible solution. you could even build a little
wireless control scheme, using off-the-shelf wireless components that
would allow you do this from a central location...

You can get and program a microcontroller (see basic stamp, or PIC, or
ATTiny, etc) that you can program to do this kind of thing. You'll need
some kind of analog circuitry to change the digital output of the
microcontroller into an analog voltage level (See R2R network). This is
very flexible, but requires reprogramming of the chip for different
kinds of cycles.

You can use some bizzare analog solution, such that the analog voltage
level is varied over time in such a way as to control your dimmer. This
is fairly inflexible, requiring changes to the hardware to change the
way it dims or brightens over time.

You can use a hybrid solution, such as a counter and DAC, which will
allow you to vary the control voltage linearly over time with
remarkable precision. This may be what the 555 guys were saying, I
don't know. Again, use a counter and R2R network to provide an analog
voltage output for your controller.

 

[Bob Monsen]

If you really want to get fancy use a micro; a bit of over kill.

The funny thing is that the micro solution is probably cheaper, more
reliable, and easier to build than anything else the OP will try.
Sadly, it takes a hardware programmer and a bit of work to learn how to
write the software for it.

--
Regards,
Bob Monsen

"Man with all his noble qualities, with sympathy which feels for the
most debased, with benevolence which extends not only to other men but
to the humblest living creature, with his god-like intellect which has
penetrated into the movements and constitution of the solar system-
with all these exalted powers- Man still bears in his bodily frame the
indelible stamp of his lowly origin."
-- Charles Darwin