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#Post#: 1331--------------------------------------------------
LJL-Xsc
By: lynx wind Date: January 25, 2014, 8:52 pm
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A customer asked me to provide dimming for the LJL-sc. I can't
easily find economical high power rheostats so I played around
with all sorts of ways to dim the bulbs easily. My supplier
doesn't stock the 5 watt 250 Ohm. I tried a 25 Ohm wire wound
rheostat 3 watt on the DC input. So far so good. Two 6 watt
bulbs consume a combined 8 watts fully bright and 2 watts fully
dim. The rheostat cuts DC voltage from 12 volts down to 6.5
volts. I'll experiment some more, but so far no smoke, no
heating.
I am calling it the LJL-Xsc - the "X" is for the "Xtra" part in
the circuit. Still pretty simple. I am deleting the extra
primary on these units because the 100:14 is a good setup and
the dimmer allows for Ecomode.
#Post#: 1333--------------------------------------------------
Re: LJL-Xsc
By: lynx wind Date: January 26, 2014, 2:21 pm
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I checked Mouser and CTS direct. The rheostat my customer wants
is not stocked and not available. I want to keep cost and
complexity down. A $2-5 rheostat is Ok, I'll keep looking. Let
me know if you find a reasonably priced 250 Ohm 5 watt anywhere
that is available. Yes, there are lots of ways to dim the
lights, I am just looking for simple. I don't mind making these
if they are simple.
Here is a video of the latest LJL-Xsc. I left it run for hours
and it holds up well. I haven't tried CFLs or Cree bulbs yet.
To fully test i have to anticipate everything a customer might
do.
The thing I liked originally about the LJL-sc is that it handles
different bulbs better than the aircore units I used to make.
HTML http://youtu.be/ntLRgbEm438
HTML http://youtu.be/ntLRgbEm438
#Post#: 1353--------------------------------------------------
Re: LJL-Xsc
By: pbezza Date: January 28, 2014, 7:23 pm
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Wouldn't 25ohms decrease the amount that you can dim the
light/s?
#Post#: 1355--------------------------------------------------
Re: LJL-Xsc
By: lynx wind Date: January 28, 2014, 9:13 pm
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I have four LED bulbs in recessed light fixtures in our family
room. They are on house power and a dimmer. They act very much
like the LED bulbs on the LJL-Xsc. 25 Ohms wont completely cut
the power to off, but the bulbs turn down to about candlelight.
My main goal is to keep this circuit simple and robust. If the
25 Ohm for $3.59 does the job, then it is a good choice for me.
Students around the world are making these circuits and learning
the basics of electricity and how the circuit works. Nothing
better than hands on learning.
#Post#: 1357--------------------------------------------------
Re: LJL-Xsc
By: pbezza Date: January 29, 2014, 2:27 am
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Candlelight would be okay. Hats off to you all for the research
and discoveries. I have enough parts to make these ccts and have
researched suitable dimmers. Have stalled on purchasing a dimmer
based on price, reliability and performance just from reading
this thread. Other than that, I'm unemployed so the wife doesn't
appreciate me spending money on my umpteen dozen hobbies.
#Post#: 1369--------------------------------------------------
Re: LJL-Xsc
By: pbezza Date: January 29, 2014, 8:01 pm
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Good job crazyguy. What are the resistor wattage ratings? Using
common, cheap parts - fantastic!
#Post#: 1371--------------------------------------------------
Re: LJL-Xsc
By: Rooth Date: January 30, 2014, 2:51 am
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Hello Crazyguy !
Congratulations for the work! Good job ;D .
What do you think would look scheme with 220v bulbs?
I tried the version with 12-14 T AWG 28 in primary and 24 AWG
100T with 220V , and CFL bulb flashes me.
I played with the primary windings by adding or decrease but
more than that I do not work.
Where can it be wrong of me?
I will try the last version you posted.
#Post#: 1372--------------------------------------------------
Re: LJL-Xsc
By: pbezza Date: January 30, 2014, 3:29 am
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I was looking at some cheap '12V 8Amp PWM Dimmer Controller
Switches for LED Ribbon Strip Lights'
HTML http://www.ebay.com.au/itm/DC-12V-8A-LED-Light-Strip-Dimmer-Adjustable-Brightness-Controller-Color-BY/200988739143?_trksid=p5713.m2061&_trkparms=aid%3D333005%26algo%3DRIC.FIT%26ao%3D1%26asc%3D25%26meid%3D4478518913387240748%26pid%3D100041%26prg%3D1010%26rk%3D4%26rkt%3D9%26sd%3D151166060891%26<br
/>and
HTML http://www.ebay.com.au/itm/Mini-Single-Color-LED-Light-Dimmer-Controller-for-3528-5050-LED-Light-Strip-/151166060891?pt=AU_Lighting_Fans&hash=item233233095b&_uhb=1<br
/>wondering what effect their PWM would have on the cct function
or whether they could be used in a seperate cct design
accompanied with a FET. I have ordered a couple to muck around
with.
#Post#: 1569--------------------------------------------------
Re: LJL-Xsc
By: lynx wind Date: February 19, 2014, 1:20 pm
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It's been awhile and I forgot to update this thread. I did
install the 250 Ohm 5 watt wire wound rheostats I received from
Mouser electronics. I tested two of the LJL-xsc for two weeks
and sent them off to a customer. At "full on" the bulbs are
bright and at about half of the dial the bulbs are just
candlelight. The dimming is very smooth and provides the amount
of light you want. When the dial is turned all the way to 250
Ohms the circuits still pulls 20 ma.
But I never experienced any heating or smoking of the rheostat
and the unit seems quite reliable. I'll have to see if there is
a way to open the pot and rig it to turn completely off.
This is something that could be added to any of the LJL 3.0 4.0
or 5.0 or LJL-sc circuits that are out there. Just put the
rheostat in the positive or negative DC line. The rheostat was
about $3.75 from Mouser electronics. 250 Ohm 5 watt wire wound
pot. Radio Shack sells a 4 pack of knobs for a few $.
#Post#: 1690--------------------------------------------------
Re: LJL-Xsc
By: lynx wind Date: March 5, 2014, 5:50 pm
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Probably sharpens the wave form with a crisp signal to the base
instead of a building voltage triggering the transistor. I'll
try it. Makes sense.
The reason I liked the LJL SC was it was the first circuit that
would light CFL, Ecosmart and Cree bulbs. Now if its better -
hurray!
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