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FADER CIRCUITS

Discussion in 'General Electronics Discussion' started by Warlord, Jul 1, 2014.

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  1. Warlord

    Warlord

    14
    1
    Jul 1, 2014
    I build light house and need to know if there is a ac fader circuit to run one or up to four channel circuits ???
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    10,593
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    Nov 17, 2011
    Welcom aboard our forum.

    You're not being too specific as to the properties of your fader. Do you mean a dimmer? If not, please describe in more detail what you expect the fader to do. I'm sure there will be a solution.
     
  3. Warlord

    Warlord

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    Jul 1, 2014
    Well like if I have LED's hooked up to a fader circuit that makes them come on and then go off, then back on and then back off again. Give the effect that the light in the light house is going around.
     
  4. shumifan50

    shumifan50

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    Jan 16, 2014
    I assume this is a model lighthouse and not the real thing.

    I would use a microcontroller that has PWM outputs (like a PIC) and program it to drive the LED(s) in the lighthouse. That way you can control the speed at which you fade them in/out as well as the period they are on quite easily. As light houses each have their own signature pattern, it would also be possible to program the pattern of on/off. You could even drive a fog horn from the microcontroller.
     
    Harald Kapp likes this.
  5. Warlord

    Warlord

    14
    1
    Jul 1, 2014
    Would you know of any sites where I could get circuit diagrams from on this?? And thank you very much !!!
     
  6. shumifan50

    shumifan50

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    Jan 16, 2014
    if you update your profile to show your location then somebody might be able to help you better. There are several clubs here in England that do model railroad electronics and you might even be able to get a kit from them. MERG.co.uk is a good club with many circuits and knockdown component/kit prices.
    You don't really need a circuit diagram for the circuit you want to build as it will have one microcontroller, a transistor(see below), voltage regulator with some filter caps and maybe some pushbuttons with pullup resistors. If you search on the web you will find many circuits.
    Just bear in mind that a PIC can drive a single LED on a output pin, but current is limited to 20ma typically. As you are at model scale your lighthouse will most likely only have one LED, so you can drive that directly off the PIC pin without a transistor.

    One of the smaller PICs should be able to do the job e.g. 12F675 or 12F1840. Read the datasheet. The circuits are very simple, which is the attraction of using microcontrollers - the same circuit can be used for many different projects sometimes. The downside is that they need programming (writing programs in C or assembler) and flashing the program onto the chip(need an programmer like a PicKit3 with development IDE like MPLABX).

    The added advantage is that you get timers 'for free' to time your on/off/fading periods.

    I am sure somebody here can provide you with a circuit diagram to just flash the LED, or even fade it on and off, without using a microcontroller, but I would make the investment in doing it with a microcontroller as it opens a whole new world of possibilities.
    I developed a whole CAB control system using PICs and smartphones/PDAs/PCs to control my grandson's layout. It has a graphical interface, so you just click/tap on icons to make them happen or you can program entire routes at the click of an Icon.
     
  7. dpk

    dpk

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    Jul 6, 2014
    surely you can go for triac to control the intensity of light controlled.
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    That might be overkill for a model, and it's not going to work for DC. :)
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    That might be overkill for a model, and it's not going to work for DC. :)
     
  10. shumifan50

    shumifan50

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    Jan 16, 2014
    Just one further thought: You could use an accessory controller (like the one used for points) to control the light from your CAB controller to turn it on and off. Or you could use a photo sensitive resistor and automatically turn the lighthouse light on below a certain light level - the PIC can read the light intensity using the resistor.
    Several hobby sites sell standard flashing LEDs and you could hack one of those if you just want simple flashing. You could also search for 'flashing led circuits' using NE555 or the like.

    I now use PICs to control the points on my grandson's layout and instead of using the very unsatisfactory Tortoise point motors, I use servo;s that allows me to control the speed at which the points are moved and also the throw. The controller uses a 12f6xx to handle 4 sets of points. Initially i used the switched output from an accessory controller to trigger the movement, but Merg had the circuit for receiving the output from the CAB directly, so the last 2 I built work without the accessory decoder(it uses a 28 pin PIC).
     
  11. Warlord

    Warlord

    14
    1
    Jul 1, 2014
    Well when I make bigger light house, I use the controllers for Christmas lights that have 4 channel functions that make them fade on and off. But this is a smaller version of a light house and thought to use LED's instead of lamps like I can with the other. Do want to thank everyone's help. I will be back knowing I can get sound advice !!!
     
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