Forums » General Electronics Discussion

I am using a Bosch Torpedo Laser Lever to level the sub-floor in a 50 year old house. My gage study of this tool showed that operator to operator variation exceeded the requriements of the job spec. I've been able to reduce variation to an acceptable level by adding a magnifying sight tube to the device but. to work it needs consistent, stable, illumination of the bubblle. I picked up an Ultra High Brightness White LED from Radio Shack for this purpose but, they don't provide a detailed spec sheet for this part. I checked the manufacturers website. The have spec sheets for many LEDs but not for this critter. I have the following information:

Manufacturer: RoHS
Part# 276-0005
Intensity: 28,500mcd (typical)
Veiwing Angle 10 degrees
FW current  20 mA
FW supply 3.5V typical, 4V max

Does anyone have, or know where I can get a spec sheet for this part?

RoHS is not a manufacturer:

http://en.wikipedia.org/wiki/Restriction_of_Hazardous_Substances_Directive

You already have:

FW current 20 mA FW supply 3.5V typical, 4V max

then what more do you need to know to use the device?

From what I've seen Radio Shack's device data is poor to appalling.

If you need reliable info such as colour temperature or considtency from device to device etc., then don't buy from Radio Shack; buy from a dedicated LED vendor or manufacturer.

I need the information to fill out the device parameter fields in this simulation. As far as RadioShack being a lousey place to buy components, I agree but, when you need an LED on a saturday afternoon in un-named town in Arkansas, you options are limited.

For the purposes of a simulation you can set the LED up as a generic part. Unless you are trying to switch it on and off at some rate above a few kHz then the driver circuit should - by design - be tolerant of variations of device parameters.

For your purposes you may only need a simple linear 20mA constant current source to drive the LED.

For a single LED at only 20mA you may not need to go to the complexity of an switch mode supply.

With 4 off AAA or AA batteries (6V) then if the LED drops 3.5V the LED power dissipation is 70mW and the current source dissipates 50mW. 3 off batteries may not give enough headroom between the battery voltage of 4.5V and the max LED drop to give reliable LED current regulation. The battery voltage would only have to drop slightly and the current may start to droop.

https://www.circuitlab.com/circuit/f646vh/2-transistor-constant-current-sink-01/

https://www.circuitlab.com/circuit/63wt5z/constant-current-source-led-driver-linear-01/

https://www.circuitlab.com/circuit/7aavyg/constant-current-sink-led-driver-linear-01/

On the other hand, an SMPS Boost converter would allow you to use one or two 1.5V batteries and be able to drive the LED at a constant current at lower battery voltage.

There are lots of off the shelf LED driver chips. See this thread for more info:

https://www.circuitlab.com/forums/analog-design/topic/ek3255rr/current-transformer-and-led/

https://www.circuitlab.com/forums/basic-electronics/topic/w2ks25f4/volts-or-amps/

Here's a thread about how to edit a diode to make it look like a generic LED:

https://www.circuitlab.com/forums/optoelectronics/topic/6vu3zs7w/how-to-add-an-anonymous-led/

You could search Farnell or DigiKey for a device with similar parameters to the one you've got and from there find the datasheet for it. From there - if you're lucky - you may be able to find a SPICE model for it. Don't hold your breath though; compared to things like bipolar transistors, fets and opamps, there are relatively few LEDs that have spice models.