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70 Posts
Discussion Starter #1
Re: [EVDL] LED Taillights - more info

can you string LED lights to use higher voltages? for
example if i had 4 12 volt plug-n-play brake lights in
series could i use that at 48 volts?

harry

Albuquerque, NM
http://geocities.com/hendersonmotorcycles/blog.html
http://www.austinev.org/evalbum/1221
http://geocities.com/solarcookingman


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Discussion Starter #2
Re: [EVDL] LED Taillights - more info

Harry,

I used two of the same 12 volt led trailer marker lights in series on a
24 volt Razor scooter for my daughter. They work very well together.
When she turns the unit on, the marker lights come on, even in the day
light.

I can't say if this would work up to 48 volts. However, if one unit,
wire, connection goes bad you lose four lights.

I am looking at 36 and 48 volt lights for electric forklifts for my
project, especially the headlight, something that I had overlooked at
first.

Alan

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of dale henderson
Sent: Thursday, September 27, 2007 1:43 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] LED Taillights - more info

can you string LED lights to use higher voltages? for
example if i had 4 12 volt plug-n-play brake lights in
series could i use that at 48 volts?

harry

Albuquerque, NM
http://geocities.com/hendersonmotorcycles/blog.html
http://www.austinev.org/evalbum/1221
http://geocities.com/solarcookingman



________________________________________________________________________
____________
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panel and lay it on us.
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Discussion Starter #4
Re: [EVDL] LED Taillights - more info

Short answer is probably wrong!

Many of these ready-made LED packages used a tiny switching power supply
on board to not only create a constant current but do so with a
relatively efficient DC/DC converter instead of just burning up the
extra voltage. These can't be put in series.

Danny

TrotFox Greyfoot wrote:

>Short answer is Yes.
>
>Just be aware of the issue associated with loosing any one of the
>units or connections... they'll all go out.
>
>Trot, the electronically-minded, fox...
>
>On 9/27/07, dale henderson <[email protected]> wrote:
>
>
>>can you string LED lights to use higher voltages? for
>>example if i had 4 12 volt plug-n-play brake lights in
>>series could i use that at 48 volts?
>>
>>harry
>>
>>Albuquerque, NM
>>http://geocities.com/hendersonmotorcycles/blog.html
>>http://www.austinev.org/evalbum/1221
>>http://geocities.com/solarcookingman
>>
>>
>
>
>
>

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Discussion Starter #8
Re: [EVDL] LED Taillights - more info

is there an simple [non EE degree] solution to reduce
48 volts to 12 volt to power a 120ma led break light?


--- Cor van de Water <[email protected]> wrote:

> Actually I built a 120V AC LED light myself.
> It has about 30 LEDs in series (depending on color,
> white LEDs create a blue light and therefor the
> LED voltage drop is about 3 to 4V.
> I decided to not use a series resistor to drop the
> remaining voltage, but to use a circuit that I found
> many years ago in an IR sensor of an outdoor
> floodlight
> consisting of a capacitor dimensioned to create the
> wanted current with the AC voltage present,
> this cap is in between the grid and the rectifier,
> (with a little series resistor to remove spikes)
> the output of the rectifier goes to a elco and the
> DC current from this elco goes through all the LEDs.
> This avoids that the LEDs blink, so it gives a very
> constant output.
> Advantage of this circuit is that the capacitor is
> an almost lossless adapter of AV voltage to current
> and the voltage at the output can be virtually
> anything
> between the grid voltage (or even a little higher)
> and
> almost zero.
> The series capacitor should be dimensioned to barely
> carry the max average current and the output can
> be stabilized by a single zener if the power is low
> enough.
> Only drawback is that the circuit is directly
> connected
> to the grid, so a good isolation is necessary
> (plastic housing and no way to touch the outputs)
> but very few parts required.
>
> Of course a DC-fed lamp is even simpler, using a
> series of LEDs and (power) resistor, or a DC/DC.
>
> The circuit for the simple AC supply:
>
> C | | __ R
> ---| |-|__|-+--------+
> | | __|__ __|__
> / \ \ /
> /___\ _\_/_
> | |
> AC +---+ +-------+----
> in | __|__ __|__ | +
> | \ / / \ --- DC
> | _\_/_ /___\ --- out
> | | | C |
> --------|---+--------+ | -
> +--------------------+----
> R is typically 100 ohm or less,
> just to avoid that a spike kills the rectifier.
> C is typical around 1 uF 200V AC (or 400V in 230V AC
> countries)
> for an output in the order of 10 mA but it depends
> on the
> output voltage, because the input C and output C
> form a
> capacitive voltage divider, so the output current
> gets higher
> at lower output voltages.
>
> Cor van de Water
> Systems Architect
> Proxim Wireless Corporation http://www.proxim.com
> Email: [email protected] Private:
> http://www.cvandewater.com
> Skype: cor_van_de_water IM:
> [email protected]
> Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD#
> 25925
> Fax: +1 408 731 3675 eFAX: +31-87-784-1130
> Second Life:
>
www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of
> Marty Hewes
> Sent: Thursday, September 27, 2007 6:52 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] LED Taillights - more info
>
> I've got an LED replacement bulb in my night light
> in the bathroom. Granted it's not very bright, but
> it does make me wonder if there are LED incandescent
> lamp replacements out there that would work on DC
> pack voltage?
>
> ----- Original Message -----
> From: "TrotFox Greyfoot" <[email protected]>
> To: "Electric Vehicle Discussion List"
> <[email protected]>
> Sent: Thursday, September 27, 2007 8:45 PM
> Subject: Re: [EVDL] LED Taillights - more info
>
>
> > True dat. Although, with some bypass caps (for
> the pulses) you might
> > still be able to get them to work? It'd be an
> interesting experiment.
> > I wouldn't go too high with the supply voltage on
> such a system
> > though. { : ]
> >
> > So far every one I've touched has turned out to be
> resistor-limited.
> > : ( I know there are better devices out there,
> just haven't seen one
> > myself.
> >
> > Trot, the gray, fox...
> >
> > On 9/27/07, Danny Miller <[email protected]>
> wrote:
> >> Short answer is probably wrong!
> >>
> >> Many of these ready-made LED packages used a tiny
> switching power supply
> >> on board to not only create a constant current
> but do so with a
> >> relatively efficient DC/DC converter instead of
> just burning up the
> >> extra voltage. These can't be put in series.
> >>
> >> Danny
> >>
> >> TrotFox Greyfoot wrote:
> >>
> >> >Short answer is Yes.
> >> >
> >> >Just be aware of the issue associated with
> loosing any one of the
> >> >units or connections... they'll all go out.
> >> >
> >> >Trot, the electronically-minded, fox...
> >> >
> >> >On 9/27/07, dale henderson
> <[email protected]> wrote:
> >> >
> >> >
> >> >>can you string LED lights to use higher
> voltages? for
> >> >>example if i had 4 12 volt plug-n-play brake
> lights in
> >> >>series could i use that at 48 volts?
> >> >>
> >> >>harry
> >> >>
> >> >>Albuquerque, NM
> >>
>
>>http://geocities.com/hendersonmotorcycles/blog.html
> >> >>http://www.austinev.org/evalbum/1221
> >> >>http://geocities.com/solarcookingman
> >> >>
> >> >>
> >> >
> >> >
> >> >
> >> >
> >>
> >> _______________________________________________
> >> For subscription options, see
> >> http://lists.sjsu.edu/mailman/listinfo/ev
> >>
> >
> >
> > --
> > | /\_/\ TrotFox \ Always remember,
> > | ( o o ) AKA Landon Solomon \ "There is a
> > | >\_/< [email protected] \ third
> alternative."
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>


harry

Albuquerque, NM
http://geocities.com/hendersonmotorcycles/blog.html
http://www.austinev.org/evalbum/1221
http://geocities.com/solarcookingman


____________________________________________________________________________________
Don't let your dream ride pass you by. Make it a reality with Yahoo! Autos.
http://autos.yahoo.com/index.html



_______________________________________________
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70 Posts
Discussion Starter #9
Re: [EVDL] LED Taillights - more info

Yes, with a constant resistive load like an LED, a simple series
resistor is all you need.

You want to deliver 120mA, and you want to drop 36V across your
resistor, leaving the other 12V for the light. Ohm's law says E/I = R,
so 36/.120 = 300. That resistor has to dissipate the waste heat,
expressed as P = E*I, or 36 * .12 = 4.32 Watts. A 10 Watt ceramic or
cement resistor will do nicely - the first one on this page is $.55 ea:

http://www.mouser.com/search/Refine.aspx?Ne=1447464+254016+688665+688632+254411&N=1323038+4294940103+4294955608+254411&GetRecs=1&Ns=P_SField&Msb=0&RefType=Header

- kent

On Wed, 3 Oct 2007 10:24:38 -0700 (PDT), "dale henderson"
<[email protected]> said:
>
> is there an simple [non EE degree] solution to reduce
> 48 volts to 12 volt to power a 120ma led break light?
>
>
> --- Cor van de Water <[email protected]> wrote:
>
> > Actually I built a 120V AC LED light myself.
> > It has about 30 LEDs in series (depending on color,
> > white LEDs create a blue light and therefor the
> > LED voltage drop is about 3 to 4V.
> > I decided to not use a series resistor to drop the
> > remaining voltage, but to use a circuit that I found
> > many years ago in an IR sensor of an outdoor
> > floodlight
> > consisting of a capacitor dimensioned to create the
> > wanted current with the AC voltage present,
> > this cap is in between the grid and the rectifier,
> > (with a little series resistor to remove spikes)
> > the output of the rectifier goes to a elco and the
> > DC current from this elco goes through all the LEDs.
> > This avoids that the LEDs blink, so it gives a very
> > constant output.
> > Advantage of this circuit is that the capacitor is
> > an almost lossless adapter of AV voltage to current
> > and the voltage at the output can be virtually
> > anything
> > between the grid voltage (or even a little higher)
> > and
> > almost zero.
> > The series capacitor should be dimensioned to barely
> > carry the max average current and the output can
> > be stabilized by a single zener if the power is low
> > enough.
> > Only drawback is that the circuit is directly
> > connected
> > to the grid, so a good isolation is necessary
> > (plastic housing and no way to touch the outputs)
> > but very few parts required.
> >
> > Of course a DC-fed lamp is even simpler, using a
> > series of LEDs and (power) resistor, or a DC/DC.
> >
> > The circuit for the simple AC supply:
> >
> > C | | __ R
> > ---| |-|__|-+--------+
> > | | __|__ __|__
> > / \ \ /
> > /___\ _\_/_
> > | |
> > AC +---+ +-------+----
> > in | __|__ __|__ | +
> > | \ / / \ --- DC
> > | _\_/_ /___\ --- out
> > | | | C |
> > --------|---+--------+ | -
> > +--------------------+----
> > R is typically 100 ohm or less,
> > just to avoid that a spike kills the rectifier.
> > C is typical around 1 uF 200V AC (or 400V in 230V AC
> > countries)
> > for an output in the order of 10 mA but it depends
> > on the
> > output voltage, because the input C and output C
> > form a
> > capacitive voltage divider, so the output current
> > gets higher
> > at lower output voltages.
> >
> > Cor van de Water
> > Systems Architect
> > Proxim Wireless Corporation http://www.proxim.com
> > Email: [email protected] Private:
> > http://www.cvandewater.com
> > Skype: cor_van_de_water IM:
> > [email protected]
> > Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD#
> > 25925
> > Fax: +1 408 731 3675 eFAX: +31-87-784-1130
> > Second Life:
> >
> www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
> >
> > -----Original Message-----
> > From: [email protected]
> > [mailto:[email protected]] On Behalf Of
> > Marty Hewes
> > Sent: Thursday, September 27, 2007 6:52 PM
> > To: Electric Vehicle Discussion List
> > Subject: Re: [EVDL] LED Taillights - more info
> >
> > I've got an LED replacement bulb in my night light
> > in the bathroom. Granted it's not very bright, but
> > it does make me wonder if there are LED incandescent
> > lamp replacements out there that would work on DC
> > pack voltage?
> >
> > ----- Original Message -----
> > From: "TrotFox Greyfoot" <[email protected]>
> > To: "Electric Vehicle Discussion List"
> > <[email protected]>
> > Sent: Thursday, September 27, 2007 8:45 PM
> > Subject: Re: [EVDL] LED Taillights - more info
> >
> >
> > > True dat. Although, with some bypass caps (for
> > the pulses) you might
> > > still be able to get them to work? It'd be an
> > interesting experiment.
> > > I wouldn't go too high with the supply voltage on
> > such a system
> > > though. { : ]
> > >
> > > So far every one I've touched has turned out to be
> > resistor-limited.
> > > : ( I know there are better devices out there,
> > just haven't seen one
> > > myself.
> > >
> > > Trot, the gray, fox...
> > >
> > > On 9/27/07, Danny Miller <[email protected]>
> > wrote:
> > >> Short answer is probably wrong!
> > >>
> > >> Many of these ready-made LED packages used a tiny
> > switching power supply
> > >> on board to not only create a constant current
> > but do so with a
> > >> relatively efficient DC/DC converter instead of
> > just burning up the
> > >> extra voltage. These can't be put in series.
> > >>
> > >> Danny
> > >>
> > >> TrotFox Greyfoot wrote:
> > >>
> > >> >Short answer is Yes.
> > >> >
> > >> >Just be aware of the issue associated with
> > loosing any one of the
> > >> >units or connections... they'll all go out.
> > >> >
> > >> >Trot, the electronically-minded, fox...
> > >> >
> > >> >On 9/27/07, dale henderson
> > <[email protected]> wrote:
> > >> >
> > >> >
> > >> >>can you string LED lights to use higher
> > voltages? for
> > >> >>example if i had 4 12 volt plug-n-play brake
> > lights in
> > >> >>series could i use that at 48 volts?
> > >> >>
> > >> >>harry
> > >> >>
> > >> >>Albuquerque, NM
> > >>
> >
> >>http://geocities.com/hendersonmotorcycles/blog.html
> > >> >>http://www.austinev.org/evalbum/1221
> > >> >>http://geocities.com/solarcookingman
> > >> >>
> > >> >>
> > >> >
> > >> >
> > >> >
> > >> >
> > >>
> > >> _______________________________________________
> > >> For subscription options, see
> > >> http://lists.sjsu.edu/mailman/listinfo/ev
> > >>
> > >
> > >
> > > --
> > > | /\_/\ TrotFox \ Always remember,
> > > | ( o o ) AKA Landon Solomon \ "There is a
> > > | >\_/< [email protected] \ third
> > alternative."
> > >
> > > _______________________________________________
> > > For subscription options, see
> > > http://lists.sjsu.edu/mailman/listinfo/ev
> > >
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
> > _______________________________________________
> > For subscription options, see
> > http://lists.sjsu.edu/mailman/listinfo/ev
> >
>
>
> harry
>
> Albuquerque, NM
> http://geocities.com/hendersonmotorcycles/blog.html
> http://www.austinev.org/evalbum/1221
> http://geocities.com/solarcookingman
>
>
> ____________________________________________________________________________________
> Don't let your dream ride pass you by. Make it a reality with Yahoo!
> Autos.
> http://autos.yahoo.com/index.html
>
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
For subscription options, see
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·
Registered
Joined
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70 Posts
Discussion Starter #10
Re: [EVDL] LED Taillights - more info

Sorry to nit-pick, but surely an LED is a nonlinear diode junction that
requires a constant current supply. I think you meant to say that the
LED load does not change.
-
Martin K

Kent Forschmiedt wrote:
> Yes, with a constant resistive load like an LED, a simple series
> resistor is all you need.
>
> You want to deliver 120mA, and you want to drop 36V across your
> resistor, leaving the other 12V for the light. Ohm's law says E/I = R,
> so 36/.120 = 300. That resistor has to dissipate the waste heat,
> expressed as P = E*I, or 36 * .12 = 4.32 Watts. A 10 Watt ceramic or
> cement resistor will do nicely - the first one on this page is $.55 ea:
>
> http://www.mouser.com/search/Refine.aspx?Ne=1447464+254016+688665+688632+254411&N=1323038+4294940103+4294955608+254411&GetRecs=1&Ns=P_SField&Msb=0&RefType=Header
>
> - kent
>
> On Wed, 3 Oct 2007 10:24:38 -0700 (PDT), "dale henderson"
> <[email protected]> said:
>
>> is there an simple [non EE degree] solution to reduce
>> 48 volts to 12 volt to power a 120ma led break light?
>>
>>
>

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70 Posts
Discussion Starter #11
Re: [EVDL] LED Taillights - more info

Perhaps I should have said, "...like an LED lamp assembly." They come
with a resistor or power supply so it acts very similar to a constant
resistive load ;)

- kent

On Wed, 03 Oct 2007 14:15:38 -0400, "Martin Klingensmith"
<[email protected]> said:
> Sorry to nit-pick, but surely an LED is a nonlinear diode junction that
> requires a constant current supply. I think you meant to say that the
> LED load does not change.
> -
> Martin K
>
> Kent Forschmiedt wrote:
> > Yes, with a constant resistive load like an LED, a simple series
> > resistor is all you need.
> >
> > You want to deliver 120mA, and you want to drop 36V across your
> > resistor, leaving the other 12V for the light. Ohm's law says E/I = R,
> > so 36/.120 = 300. That resistor has to dissipate the waste heat,
> > expressed as P = E*I, or 36 * .12 = 4.32 Watts. A 10 Watt ceramic or
> > cement resistor will do nicely - the first one on this page is $.55 ea:
> >
> > http://www.mouser.com/search/Refine.aspx?Ne=1447464+254016+688665+688632+254411&N=1323038+4294940103+4294955608+254411&GetRecs=1&Ns=P_SField&Msb=0&RefType=Header
> >
> > - kent
> >
> > On Wed, 3 Oct 2007 10:24:38 -0700 (PDT), "dale henderson"
> > <[email protected]> said:
> >
> >> is there an simple [non EE degree] solution to reduce
> >> 48 volts to 12 volt to power a 120ma led break light?
> >>
> >>
> >
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
For subscription options, see
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Joined
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70 Posts
Discussion Starter #12
Re: [EVDL] LED Taillights - more info

Well, a resistor if it doesn't have a switching current reg, but the
resistor will burn over 4W which is a lot of heat.
If it does have a switching power supply, and I think most do, no
there's no simple solution of wiring this-to-that.

Danny

dale henderson wrote:

>is there an simple [non EE degree] solution to reduce
>48 volts to 12 volt to power a 120ma led break light?
>
>
>--- Cor van de Water <[email protected]> wrote:
>
>
>
>>Actually I built a 120V AC LED light myself.
>>It has about 30 LEDs in series (depending on color,
>>white LEDs create a blue light and therefor the
>>LED voltage drop is about 3 to 4V.
>>I decided to not use a series resistor to drop the
>>remaining voltage, but to use a circuit that I found
>>many years ago in an IR sensor of an outdoor
>>floodlight
>>consisting of a capacitor dimensioned to create the
>>wanted current with the AC voltage present,
>>this cap is in between the grid and the rectifier,
>>(with a little series resistor to remove spikes)
>>the output of the rectifier goes to a elco and the
>>DC current from this elco goes through all the LEDs.
>>This avoids that the LEDs blink, so it gives a very
>>constant output.
>>Advantage of this circuit is that the capacitor is
>>an almost lossless adapter of AV voltage to current
>>and the voltage at the output can be virtually
>>anything
>>between the grid voltage (or even a little higher)
>>and
>>almost zero.
>>The series capacitor should be dimensioned to barely
>>carry the max average current and the output can
>>be stabilized by a single zener if the power is low
>>enough.
>>Only drawback is that the circuit is directly
>>connected
>>to the grid, so a good isolation is necessary
>>(plastic housing and no way to touch the outputs)
>>but very few parts required.
>>
>>Of course a DC-fed lamp is even simpler, using a
>>series of LEDs and (power) resistor, or a DC/DC.
>>
>>The circuit for the simple AC supply:
>>
>> C | | __ R
>>---| |-|__|-+--------+
>> | | __|__ __|__
>> / \ \ /
>> /___\ _\_/_
>> | |
>>AC +---+ +-------+----
>>in | __|__ __|__ | +
>> | \ / / \ --- DC
>> | _\_/_ /___\ --- out
>> | | | C |
>>--------|---+--------+ | -
>> +--------------------+----
>>R is typically 100 ohm or less,
>>just to avoid that a spike kills the rectifier.
>>C is typical around 1 uF 200V AC (or 400V in 230V AC
>>countries)
>>for an output in the order of 10 mA but it depends
>>on the
>>output voltage, because the input C and output C
>>form a
>>capacitive voltage divider, so the output current
>>gets higher
>>at lower output voltages.
>>
>>Cor van de Water
>>Systems Architect
>>Proxim Wireless Corporation http://www.proxim.com
>>Email: [email protected] Private:
>>http://www.cvandewater.com
>>Skype: cor_van_de_water IM:
>>[email protected]
>>Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD#
>>25925
>>Fax: +1 408 731 3675 eFAX: +31-87-784-1130
>>Second Life:
>>
>>
>>
>www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
>
>
>>-----Original Message-----
>>From: [email protected]
>>[mailto:[email protected]] On Behalf Of
>>Marty Hewes
>>Sent: Thursday, September 27, 2007 6:52 PM
>>To: Electric Vehicle Discussion List
>>Subject: Re: [EVDL] LED Taillights - more info
>>
>>I've got an LED replacement bulb in my night light
>>in the bathroom. Granted it's not very bright, but
>>it does make me wonder if there are LED incandescent
>>lamp replacements out there that would work on DC
>>pack voltage?
>>
>>----- Original Message -----
>>From: "TrotFox Greyfoot" <[email protected]>
>>To: "Electric Vehicle Discussion List"
>><[email protected]>
>>Sent: Thursday, September 27, 2007 8:45 PM
>>Subject: Re: [EVDL] LED Taillights - more info
>>
>>
>>
>>
>>>True dat. Although, with some bypass caps (for
>>>
>>>
>>the pulses) you might
>>
>>
>>>still be able to get them to work? It'd be an
>>>
>>>
>>interesting experiment.
>>
>>
>>>I wouldn't go too high with the supply voltage on
>>>
>>>
>>such a system
>>
>>
>>>though. { : ]
>>>
>>>So far every one I've touched has turned out to be
>>>
>>>
>>resistor-limited.
>>
>>
>>>: ( I know there are better devices out there,
>>>
>>>
>>just haven't seen one
>>
>>
>>>myself.
>>>
>>>Trot, the gray, fox...
>>>
>>>On 9/27/07, Danny Miller <[email protected]>
>>>
>>>
>>wrote:
>>
>>
>>>>Short answer is probably wrong!
>>>>
>>>>Many of these ready-made LED packages used a tiny
>>>>
>>>>
>>switching power supply
>>
>>
>>>>on board to not only create a constant current
>>>>
>>>>
>>but do so with a
>>
>>
>>>>relatively efficient DC/DC converter instead of
>>>>
>>>>
>>just burning up the
>>
>>
>>>>extra voltage. These can't be put in series.
>>>>
>>>>Danny
>>>>
>>>>TrotFox Greyfoot wrote:
>>>>
>>>>
>>>>
>>>>>Short answer is Yes.
>>>>>
>>>>>Just be aware of the issue associated with
>>>>>
>>>>>
>>loosing any one of the
>>
>>
>>>>>units or connections... they'll all go out.
>>>>>
>>>>>Trot, the electronically-minded, fox...
>>>>>
>>>>>On 9/27/07, dale henderson
>>>>>
>>>>>
>><[email protected]> wrote:
>>
>>
>>>>>
>>>>>
>>>>>>can you string LED lights to use higher
>>>>>>
>>>>>>
>>voltages? for
>>
>>
>>>>>>example if i had 4 12 volt plug-n-play brake
>>>>>>
>>>>>>
>>lights in
>>
>>
>>>>>>series could i use that at 48 volts?
>>>>>>
>>>>>>harry
>>>>>>
>>>>>>Albuquerque, NM
>>>>>>
>>>>>>
>>>http://geocities.com/hendersonmotorcycles/blog.html
>>>
>>>
>>>>>>http://www.austinev.org/evalbum/1221
>>>>>>http://geocities.com/solarcookingman
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>_______________________________________________
>>>>For subscription options, see
>>>>http://lists.sjsu.edu/mailman/listinfo/ev
>>>>
>>>>
>>>>
>>>--
>>>| /\_/\ TrotFox \ Always remember,
>>>| ( o o ) AKA Landon Solomon \ "There is a
>>>| >\_/< [email protected] \ third
>>>
>>>
>>alternative."
>>
>>
>>>_______________________________________________
>>>For subscription options, see
>>>http://lists.sjsu.edu/mailman/listinfo/ev
>>>
>>>
>>>
>>_______________________________________________
>>For subscription options, see
>>http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>_______________________________________________
>>For subscription options, see
>>http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>>
>
>
>harry
>
>Albuquerque, NM
>http://geocities.com/hendersonmotorcycles/blog.html
>http://www.austinev.org/evalbum/1221
>http://geocities.com/solarcookingman
>
>
> ____________________________________________________________________________________
>Don't let your dream ride pass you by. Make it a reality with Yahoo! Autos.
>http://autos.yahoo.com/index.html
>
>
>
>_______________________________________________
>For subscription options, see
>http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>

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·
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Joined
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70 Posts
Discussion Starter #16
Re: [EVDL] LED Taillights - more info

I have some ~2"x2.5" 36-72V dc:dc converters that put out both 3.3V
and 5V, but they need a minimum output load of 4 watts for either
voltage - whether they'll stay on below that, I don't know. I can dig
them out if anyone wants, price is mailing cost plus whatever they're
worth to you (by the way, that's what the band Radiohead is charging
for a download of their latest album).

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Joined
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70 Posts
Discussion Starter #17
Re: [EVDL] LED Taillights - more info

Again, this will not work if the LED element uses a switching power
supply. I believe most of the luxeon-type taillight probably do use a
switcher, since the emitter needs like 3V @ 1A they'd be burning up an
inconvenient amount of heat in a resistor. Ones made of a bunch of
small LEDs, there's a good chance that it's a bunch of strings of 3 to
make a 9V forward voltage so that's a case where the ballast resistor
solution is more reasonable and likely. Also many small strings would
typically require switch-mode electronics for each string and they
wouldn't typically want to do that for cost reasons.

Danny

Cor van de Water wrote:

>If you do not mind the losses, you could use a big resistor
>of (48-12)/0.12 = 300 Ohm and (48-12) x 0.12 = 4.3 Watts
>So a 5 Watts power resistor should be sufficient.
>
>
>Cor van de Water
>Systems Architect
>Proxim Wireless Corporation http://www.proxim.com
>Email: [email protected] Private: http://www.cvandewater.com
>Skype: cor_van_de_water IM: [email protected]
>Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
>Fax: +1 408 731 3675 eFAX: +31-87-784-1130
>Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
>
>-----Original Message-----
>From: [email protected] [mailto:[email protected]] On Behalf Of David Nelson
>Sent: Wednesday, October 03, 2007 4:53 PM
>To: Electric Vehicle Discussion List
>Subject: Re: [EVDL] LED Taillights - more info
>
>My simple way it to rely on my 48V-12V DC-DC converter in my Gizmo.
>
>http://www.austinev.org/evalbum/1328
>
>David Nelson
>
>On 10/3/07, dale henderson <[email protected]> wrote:
>
>
>>is there an simple [non EE degree] solution to reduce
>>48 volts to 12 volt to power a 120ma led break light?
>>
>>
>>--- Cor van de Water <[email protected]> wrote:
>>
>>
>>
>>>Actually I built a 120V AC LED light myself.
>>>It has about 30 LEDs in series (depending on color, white LEDs
>>>create a blue light and therefor the LED voltage drop is about 3 to
>>>4V.
>>>I decided to not use a series resistor to drop the remaining
>>>voltage, but to use a circuit that I found many years ago in an IR
>>>sensor of an outdoor floodlight consisting of a capacitor
>>>dimensioned to create the wanted current with the AC voltage
>>>present, this cap is in between the grid and the rectifier, (with a
>>>little series resistor to remove spikes) the output of the rectifier
>>>goes to a elco and the DC current from this elco goes through all
>>>the LEDs.
>>>This avoids that the LEDs blink, so it gives a very constant output.
>>>Advantage of this circuit is that the capacitor is an almost
>>>lossless adapter of AV voltage to current and the voltage at the
>>>output can be virtually anything between the grid voltage (or even a
>>>little higher) and almost zero.
>>>The series capacitor should be dimensioned to barely carry the max
>>>average current and the output can be stabilized by a single zener
>>>if the power is low enough.
>>>Only drawback is that the circuit is directly connected to the grid,
>>>so a good isolation is necessary (plastic housing and no way to
>>>touch the outputs) but very few parts required.
>>>
>>>Of course a DC-fed lamp is even simpler, using a series of LEDs and
>>>(power) resistor, or a DC/DC.
>>>
>>>The circuit for the simple AC supply:
>>>
>>> C | | __ R
>>>---| |-|__|-+--------+
>>> | | __|__ __|__
>>> / \ \ /
>>> /___\ _\_/_
>>> | |
>>>AC +---+ +-------+----
>>>in | __|__ __|__ | +
>>> | \ / / \ --- DC
>>> | _\_/_ /___\ --- out
>>> | | | C |
>>>--------|---+--------+ | -
>>> +--------------------+----
>>>R is typically 100 ohm or less,
>>>just to avoid that a spike kills the rectifier.
>>>C is typical around 1 uF 200V AC (or 400V in 230V AC
>>>countries)
>>>for an output in the order of 10 mA but it depends on the output
>>>voltage, because the input C and output C form a capacitive voltage
>>>divider, so the output current gets higher at lower output voltages.
>>>
>>>Cor van de Water
>>>Systems Architect
>>>Proxim Wireless Corporation http://www.proxim.com
>>>Email: [email protected] Private:
>>>http://www.cvandewater.com
>>>Skype: cor_van_de_water IM:
>>>[email protected]
>>>Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD#
>>>25925
>>>Fax: +1 408 731 3675 eFAX: +31-87-784-1130
>>>Second Life:
>>>
>>>
>>>
>>www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
>>
>>
>>>-----Original Message-----
>>>From: [email protected]
>>>[mailto:[email protected]] On Behalf Of Marty Hewes
>>>Sent: Thursday, September 27, 2007 6:52 PM
>>>To: Electric Vehicle Discussion List
>>>Subject: Re: [EVDL] LED Taillights - more info
>>>
>>>I've got an LED replacement bulb in my night light in the bathroom.
>>>Granted it's not very bright, but it does make me wonder if there
>>>are LED incandescent lamp replacements out there that would work on
>>>DC pack voltage?
>>>
>>>----- Original Message -----
>>>From: "TrotFox Greyfoot" <[email protected]>
>>>To: "Electric Vehicle Discussion List"
>>><[email protected]>
>>>Sent: Thursday, September 27, 2007 8:45 PM
>>>Subject: Re: [EVDL] LED Taillights - more info
>>>
>>>
>>>
>>>
>>>>True dat. Although, with some bypass caps (for
>>>>
>>>>
>>>the pulses) you might
>>>
>>>
>>>>still be able to get them to work? It'd be an
>>>>
>>>>
>>>interesting experiment.
>>>
>>>
>>>>I wouldn't go too high with the supply voltage on
>>>>
>>>>
>>>such a system
>>>
>>>
>>>>though. { : ]
>>>>
>>>>So far every one I've touched has turned out to be
>>>>
>>>>
>>>resistor-limited.
>>>
>>>
>>>>: ( I know there are better devices out there,
>>>>
>>>>
>>>just haven't seen one
>>>
>>>
>>>>myself.
>>>>
>>>>Trot, the gray, fox...
>>>>
>>>>On 9/27/07, Danny Miller <[email protected]>
>>>>
>>>>
>>>wrote:
>>>
>>>
>>>>>Short answer is probably wrong!
>>>>>
>>>>>Many of these ready-made LED packages used a tiny
>>>>>
>>>>>
>>>switching power supply
>>>
>>>
>>>>>on board to not only create a constant current
>>>>>
>>>>>
>>>but do so with a
>>>
>>>
>>>>>relatively efficient DC/DC converter instead of
>>>>>
>>>>>
>>>just burning up the
>>>
>>>
>>>>>extra voltage. These can't be put in series.
>>>>>
>>>>>Danny
>>>>>
>>>>>TrotFox Greyfoot wrote:
>>>>>
>>>>>
>>>>>
>>>>>>Short answer is Yes.
>>>>>>
>>>>>>Just be aware of the issue associated with
>>>>>>
>>>>>>
>>>loosing any one of the
>>>
>>>
>>>>>>units or connections... they'll all go out.
>>>>>>
>>>>>>Trot, the electronically-minded, fox...
>>>>>>
>>>>>>On 9/27/07, dale henderson
>>>>>>
>>>>>>
>>><[email protected]> wrote:
>>>
>>>
>>>>>>
>>>>>>
>>>>>>>can you string LED lights to use higher
>>>>>>>
>>>>>>>
>>>voltages? for
>>>
>>>
>>>>>>>example if i had 4 12 volt plug-n-play brake
>>>>>>>
>>>>>>>
>>>lights in
>>>
>>>
>>>>>>>series could i use that at 48 volts?
>>>>>>>
>>>>>>>harry
>>>>>>>
>>>>>>>Albuquerque, NM
>>>>>>>
>>>>>>>
>>>>http://geocities.com/hendersonmotorcycles/blog.html
>>>>
>>>>
>>>>>>>http://www.austinev.org/evalbum/1221
>>>>>>>http://geocities.com/solarcookingman
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>_______________________________________________
>>>>>For subscription options, see
>>>>>http://lists.sjsu.edu/mailman/listinfo/ev
>>>>>
>>>>>
>>>>>
>>>>--
>>>>| /\_/\ TrotFox \ Always remember,
>>>>| ( o o ) AKA Landon Solomon \ "There is a
>>>>| >\_/< [email protected] \ third
>>>>
>>>>
>>>alternative."
>>>
>>>
>>>>_______________________________________________
>>>>For subscription options, see
>>>>http://lists.sjsu.edu/mailman/listinfo/ev
>>>>
>>>>
>>>>
>>>_______________________________________________
>>>For subscription options, see
>>>http://lists.sjsu.edu/mailman/listinfo/ev
>>>
>>>_______________________________________________
>>>For subscription options, see
>>>http://lists.sjsu.edu/mailman/listinfo/ev
>>>
>>>
>>>
>>harry
>>
>>Albuquerque, NM
>>http://geocities.com/hendersonmotorcycles/blog.html
>>http://www.austinev.org/evalbum/1221
>>http://geocities.com/solarcookingman
>>
>>
>>
>>______________________________________________________________________
>>______________ Don't let your dream ride pass you by. Make it a
>>reality with Yahoo! Autos.
>>http://autos.yahoo.com/index.html
>>
>>
>>
>>_______________________________________________
>>For subscription options, see
>>http://lists.sjsu.edu/mailman/listinfo/ev
>>
>>
>>
>
>_______________________________________________
>For subscription options, see
>http://lists.sjsu.edu/mailman/listinfo/ev
>
>_______________________________________________
>For subscription options, see
>http://lists.sjsu.edu/mailman/listinfo/ev
>
>
>

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