Large Scale Central

LED Dimmer and Current Limiting

Electronics
#1

Is there any interest in a circuit that will dim LED’s that are too bright to a level appropriate for the use you need. LED’s have gotten so efficient they are way to bright for a lot of applications in Garden Railroads.

No resistors calculations needed, just connect, uses a 5 turn miniature potentiometer to fine tune the light output.

I have designed such a device but was wondering if there is a need for it.

Specifications:

Voltage : 7 to 32 Volts DC (DC, DCC, Battery)

Maximum Current: 15 ma (optional 20ma) Output Short Circuit protected

Minimum Current: .001 ma

Types of LED circuits : Single, series, strip, internal resistor, assembled devices from other manufacturers.

Colors : All Colors supported (1.8-4.0 volts).

Application: Head Lights, Rear Lights, Cabin, Caboose, Marker, etc

Size: .4 x .25 x .15 inches

#2

Dennis, yes there’s a need but Dallee Electronics already manufactures one. I use it to reduce the voltage output of the Streamlight C4 LED’s PCB that we install as a front headlight within locomotives. Here’s the link: http://www.dallee.com/AR%20power%20supply.htm

#3

Dallee’s appears to be $40 if it’s for part #378, VRS - adjustable DC. That’s a bit pricey for something that would replace resistor calculations. Link goes nowhere for me on Chrome.

I’d definitely be interested for a lower cost alternative if that is what you (Dennis) are offering.

#4

Mark Hadler said:

Dallee’s appears to be $40 if it’s for part #378, VRS - adjustable DC. That’s a bit pricey for something that would replace resistor calculations. Link goes nowhere for me on Chrome.

I’d definitely be interested for a lower cost alternative if that is what you (Dennis) are offering.

Mark - how about less than $0.50? You can install a small current limiting integrated circuit ( CL2N3 ) between your DC input voltage and the LED - it automatically limits the current to 20ma - details on my web page here:

http://www.trainelectronics.com/LED_Articles_2007/LED_104/index.htm

If you want to use track power or DCC you simply insert a bridge rectifier and a small capacitor before the IC.

dave

#5

Mark, “Chrome” is kind a funny that way. The link is good. I use Dallee instead of a limiting circuit, because it’s more reliable and with Streamlight’s C4 LED Technology I can dial in their PCB LED up to 6 volts with no problems and get up to 60ft. of distance from their LED’s.

Streamlights C4 Technology, Link: http://www.streamlight.com/education/bulb-types.aspx

#6

Dave: Thanks, I’m already using those for the lamps on my engines and get them from Digi-Key. I was responding to Dennis’s miniature potentiometer option for adjustability. That is something that I would like for my other lighting needs.

Rick: I got a 404 Not Found from Chrome but IE was successful. This is the reverse of my normal experience with browsers and that it is IE that usually has the problems.

#7

Rick Isard said:

Dennis, yes there’s a need but Dallee Electronics already manufactures one. I use it to reduce the voltage output of the Streamlight C4 LED’s PCB that we install as a front headlight within locomotives. Here’s the link: http://www.dallee.com/AR%20power%20supply.htm

That is nice, but it is not what I have designed.

My design prevents the LED’s from being over loaded and does not use voltage regulation but current regulation and limiting.

Will make a video soon showing how it works.

#8

Mark Hadler said:

Dallee’s appears to be $40 if it’s for part #378, VRS - adjustable DC. That’s a bit pricey for something that would replace resistor calculations. Link goes nowhere for me on Chrome.

I’d definitely be interested for a lower cost alternative if that is what you (Dennis) are offering.

My design will be much less than $40.00, looking at the 3-5 Dollar range.

#9

Mark Hadler said:

Dallee’s appears to be $40 if it’s for part #378, VRS - adjustable DC. That’s a bit pricey for something that would replace resistor calculations. Link goes nowhere for me on Chrome.

I’d definitely be interested for a lower cost alternative if that is what you (Dennis) are offering.

#10

David Bodnar said:

Mark Hadler said:

Dallee’s appears to be $40 if it’s for part #378, VRS - adjustable DC. That’s a bit pricey for something that would replace resistor calculations. Link goes nowhere for me on Chrome.

I’d definitely be interested for a lower cost alternative if that is what you (Dennis) are offering.

Mark - how about less than $0.50? You can install a small current limiting integrated circuit ( CL2N3 ) between your DC input voltage and the LED - it automatically limits the current to 20ma - details on my web page here:

http://www.trainelectronics.com/LED_Articles_2007/LED_104/index.htm

If you want to use track power or DCC you simply insert a bridge rectifier and a small capacitor before the IC.

dave

The CL2N3 is a good device and work well, but no dimming.

I have never liked trying to add resistors to LED’s to lower the light level. You change the power input and the LED light level will change and you loose the effect you want.

The only way you can maintain a constant light level is by current limiting. That way the applied voltage to the light circuit can vary but the current to the LED will remain constant.

#11

According to me Chrome is is not too good. You must use the Dallee instead of a limiting circuit, because it’s more reliable and with Streamlight’s C4 LED Technology I can dial in their PCB LED up to 6 volts with no problems and get up to 60ft. of distance from their LED’s.

pcb and assembly