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5 Volt Dimmer

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dsvs(at)ca.rr.com
Guest

Posted: Wed May 16, 2007 7:34 pm Post subject: 5 Volt Dimmer

Bob,

How is the testing going on the 5-volt dimmer you designed?  Is it close to

being ready to sell?  Thanks in advance.  Don

nuckollsr(at)cox.net
Guest

Posted: Thu May 17, 2007 7:53 am Post subject: 5 Volt Dimmer

At 08:16 PM 5/16/2007 -0700, you wrote:



 	  Quote: 	
		  



  Bob,

How is the testing going on the 5-volt dimmer you designed?  Is it close to

being ready to sell?  Thanks in advance.  Don


	


   Sorry for the delay. I'm stirring some big pots right now.

   The original idea had to be scrapped. Some products intended

   for that application don't match their spec sheets. I'd

   like to resurrect that project but it's not the fast-turn

   program that was possible had the purchased parts made the

   grade. Sorry but that item is on indefinite hold.



   Bob . . .

        ----------------------------------------

        ( "Physics is like sex: sure, it may   )

        ( give some practical results, but     )

        ( that's not why we do it."            )

        (                                      )

        (                 Richard P. Feynman   )

        ----------------------------------------

dsvs(at)ca.rr.com
Guest

Posted: Thu May 17, 2007 9:10 pm Post subject: 5 Volt Dimmer

OK  I understand that.  Can you recomend a ready built 5 volt dimmer?  I

have the lighting built in to the panel so I can not get around using a 5

volt dimmer.  Thanks.  Don



--

aurbo(at)ak.net
Guest

Posted: Fri May 18, 2007 6:04 am Post subject: 5 Volt Dimmer

Don,



Check out the LC-40 panel dimmer from Van's.



Mike



---

nuckollsr(at)cox.net
Guest

Posted: Sat May 19, 2007 5:53 am Post subject: 5 Volt Dimmer

At 06:03 AM 5/18/2007 -0800, you wrote:



 	  Quote: 	
		  



Don,



Check out the LC-40 panel dimmer from Van's.


	


    Some thoughts on the task of crafting a dimmer

    suited for 5v lighting circuits:



    First, the device cited above appears to be a

    variable duty cycle control device that delivers

    full bus voltage pulses of energy to the lamps

    but controls the average current in the lamps

    by setting the ON/OFF ratio. For example, if

    you switch a 14 volt supply on for 10 milliseconds

    and then off for 90 milliseconds, a device connected

    downstream of that switch will experience and

    average of Oout = Ein (Ton/Toff+Ton)

    = 14.0 * (10/90+10) = 1.4 Volts.



    This product appears to offer a full range of

    control for the purpose of controlling 14 volt

    lamps. When installing this style of controller

    for a 5v lighting system, the controlling

    potentiometer and associated resistors would

    want to be tailored such that max clockwise

    for the potentiometer produces a maximum duty

    cycle of 5/14 or 36%.



    The product cited appears to use strip-m-and-

    mash-em screw terminals once used by Vision

    Microsystems, recently recommended by BMA

    (See page 41 of



http://www.aeroelectric.com/articles/richter/response_1.pdf )



   These are not the best we know how to do (BWKHTD)

   for bringing wires off an assembly and into an aircraft wire

   bundle. I understand Vision Microsystems went to

   D-sub connectors for their products. I use D-sub

   connectors for ALL of my products where ever their

   capabilities are commensurate with the task.



   One might also consider pure linear dimmer controls

   like those once sold from my website but now offered

   from B&C's site at:



http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?10X358218#dim30-14



   These too are 4 to 12 volt controllers and would

   require modification of their control circuitry

   to provide the more useful 1.5 to 5 volt output

   range. Further, a pure linear controller has to toss

   off about 65 percent of total energy fed to the dimmer

   when the lamps are on full bright. Hence the need for

   heatsinks. However, these are dimming REGULATORS. Unlike

   most variable duty cycle controllers, these devices will

   maintain a constant output voltage irrespective of

   perturbations of the bus voltage that might cause

   visible fluctuations in the light produced by lamps

   downstream.



   A regulating dimmer isolates the lighting system from

   such perturbations.



   The BWNHTD mirrors methodologies but not the technology

   in years past to provide an efficient step down of

   bus voltage to the desired 1.5 - 5 volt output

   range by use of inductors, capacitors and smart

   transistors. These are a members of a large family

   of switchmode power supplies. The device I was considering

   was a commercial off the shelf product that didn't

   match it's marketing hype. One can consider a scratch

   built approach that is typified by this part.



http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,P1915



   One takes a 1.8v fixed output version of this part

   and adds the potentiometer to the feedback circuit

   to achieve a 1.8 to 5.0 volt output. Or perhaps

   a fully adjustable version will be necessary to get

   a lower min output of say 1.0 to 5 volts.



   This approach would be VERY efficient. The lost energy

   is so low that the package could be quite small and

   heat losses easily managed.



   I thought I had a quick-turn solution to offer but

   it didn't work out. So I've had to back-burner the

   project.



   Food for thought.



   Bob . . .

john(at)ballofshame.com
Guest

Posted: Sat May 19, 2007 7:08 am Post subject: 5 Volt Dimmer

Or you can use a PIC to drive a MOSFET and make a dirt cheap, simple and 

effecient switching regulator.  I've been using this approach to dim a 

bank of LEDs.



-John

 	  Quote:

nuckollsr(at)cox.net
Guest

Posted: Sat May 19, 2007 8:01 am Post subject: 5 Volt Dimmer

At 08:07 AM 5/19/2007 -0700, you wrote:



 	  Quote: 	
		  



Or you can use a PIC to drive a MOSFET and make a dirt cheap, simple and 

effecient switching regulator.  I've been using this approach to dim a 

bank of LEDs.


	


   Yes, but do you close the loop to make it regulate?

   I've used PICs for some exceedingly simplistic tasks

   like generate a square wave with off-delays between

   half cycles to prevent shoot-through on totem-pole

   output transistors. A 555 with 2 capacitors, a diode

   two resistors and a pot can be arranged to provide

   an open loop, adjustable duty cycle square wave . . .

   but the best we know how to do suggests we close

   the loop to prevent bus perturbations from making

   it through the dimmer circuit and causing the

   lights to visibly vary.



   If you want to write the code for a 12F683 chip

   that provides a closed loop, variable duty cycle

   controller, we could market programmed chips . . .

   or I'd market a dimmer and pay a royalty. I have

   several products in the works now being developed

   by others who will get a slice of the pie for the

   market life of that product.  You could use one

   pin as an input to strap the functionality for

   both 12v and 5v dimmers. I think the 683 has

   enough snort to do a dual dimmer with a lookup

   table that would cause filament lamps and LEDs

   to track each other for apparent intensity.

   Pretty cool product . . . but close the loop so

   that the output is regulated.



   If interested, let's develop a Product Function

   Specification and see what we can cook up.



   Bob . . .



        ----------------------------------------

        ( "Physics is like sex: sure, it may   )

        ( give some practical results, but     )

        ( that's not why we do it."            )

        (                                      )

        (                 Richard P. Feynman   )

        ----------------------------------------

dsvs(at)ca.rr.com
Guest

Posted: Sat May 19, 2007 3:38 pm Post subject: 5 Volt Dimmer

Bob,

I could put up with the strip and mash connectors as I use ferrules that

give insulation support for this type of connector and, not the nest, but

adequate electrical connection.  Can you provide a wire diagram for the

needed support parts if I use one Pot ?  Thanks in advance.



--

nuckollsr(at)cox.net
Guest

Posted: Mon May 21, 2007 6:35 am Post subject: 5 Volt Dimmer

At 04:38 PM 5/19/2007 -0700, you wrote:



 	  Quote: 	
		  



Bob,

I could put up with the strip and mash connectors as I use ferrules that

give insulation support for this type of connector and, not the nest, but

adequate electrical connection.  Can you provide a wire diagram for the

needed support parts if I use one Pot ?  Thanks in advance.


	


  Not sure what you're asking. I have now knowledge of the products

  offered by others but I can sketch a diagram for a switchmode supply

  based on one of the off-the-shelf chips. Is this what you're wanting?



  Bob . . .

dsvs(at)ca.rr.com
Guest

Posted: Mon May 21, 2007 3:06 pm Post subject: 5 Volt Dimmer

Bob,

I was asking for a diagram of what you were talking in  the excerp from your May 19 E-Mail.

The pertinent part is included  below



 This product appears to offer a full range  of

    control for the purpose of controlling 14  volt

    lamps. When installing this style of  controller

    for a 5v lighting system, the  controlling

    potentiometer and associated resistors  would

    want to be tailored such that max  clockwise

    for the potentiometer produces a maximum  duty

    cycle of 5/14 or 36%.



     The product cited appears to use strip-m-and-

    mash-em  screw terminals once used by Vision

    Microsystems, recently  recommended by BMA

    (See page 41  of

--

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