Electronic – How to build constant current circuit

constant-currentledled-driver

I am an amateur grower of Capsicum Cayenne Chilli and have been experimenting for some years with good results using Compact Fluorescent Lamps in a small indoor grow room, but I am now looking to experiment with the new LED technology.

The supplier of the LED’s tells me that in order to run these units I need to build a ‘current sink circuit’ that will run the LED’s slightly lower than their maximum rating, suggesting that I should ask the good people of the Electrical Engineering forum for advice.

As a sculptor with a good grounding in mechanical engineering I am practically minded so shouldn’t find the physical build a problem [soldering small components for example] but I know precious little about Electrical circuitry, circuit diagrams and components: in this regard I am a complete novice.

That being said I am always keen to learn a new skill.

My question then is:

How do I build a Constant Current Circuit in order to run a bank of 40 x 3 W LED’s [these will be in two separate strips of 20 LED] and what components do I need to purchase? [I am based in the UK]

Any help or advice, links to videos etc would be very much appreciated.

Best Answer

A general analogue answer would be use an op-amp and power transistor like this: -

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There are plenty of other ways though: -

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But if you need a bit more power you could go to a PWM solution: -

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But you don't have to build one. This is an AC in LED out type module: -

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Use your google fu!

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