Hello everyone,

I need your help on design a « power supply ».

Context : We are working on a product that we might sell one day : a grow light. We want to be able to daisy chain them and in order to reduce the weight and the cost, I want to « put out » the heavy and costly stuff.

Basically put the transformer outside the devices. The transformer circuit will deliver 48V AC and up to 20A. One main grow light will be connected on it. And another power supply circuit in this grow light will make that 48V AC into 48V DC regulated and be able to deliver up to 2A. And another grow light can be connected on that one (but it will take the power directly from the main source) etc etc.

But I dont know if what I am trying to do is possible and really cheaper and practical.

Please look at the attachements for more information. And please let me know what you think about it.

If you have any question, please feel free to ask. Thank you for your help.

Niels

(Sorry for my english)

 

hi Niels,
Welcome to AAC,
Your desired scheme looks OK to me.
The Mains to 48Vac at 20Amp transformer will be OK for the 3 , 48Vdc at 2Amps.
I would add a fuse in each regulated 48Vac input supply.
E

 

A 48 volt 20 amp transformer (About 1 KVA) will be more expensive than a switch mode power supply giving 48 volts DC output. If you are dropping the 230 volts down to 48 volts for safety reasons then you can have a constant current circuit (Assuming this is LED lighting.) in each light unit. If you do not need to drop down to 48 volts for power distribuion then off the shelf constant current LED drivers in each light unit is probably the cheapest solution.

Les.

 

Hello,

thank you for you quick replies. I will add some informations.

The Mains to 48Vac at 20Amp transformer will be OK for the 3 , 48Vdc at 2Amps.

@ericgibbs I put only three there, but the maximum will be eight, but I think it will still be ok.

A 48 volt 20 amp transformer (About 1 KVA) will be more expensive than a switch mode power supply giving 48 volts DC output. If you are dropping the 230 volts down to 48 volts for safety reasons then you can have a constant current circuit (Assuming this is LED lighting.) in each light unit. If you do not need to drop down to 48 volts for power distribuion then off the shelf constant current LED drivers in each light unit is probably the cheapest solution.

@LesJones I had in my mind several solutions:

• Switch mode power supply 48v 2A in each light (the COB I use need 40V Max at 1.5A):
  • Get expensive for the consumer if you buy several unit
  • Lifespand ? (I want my grow light to last long)
  • Might be heavy and take space
• Transformerless power supply (I wanted to go with that but ...):
  • Reliability ?
  • Safety ?
  • I do not know how to design a circuit like that for 2A
• The one I propose:
  • The more you buy the less expensive it gets (that was the idea ...)
  • Reliable
  • Safe

I have a constant circuit current that control my led, but I cannot use an off the shelf one because it is control by a microcontroller, to achieve specific light patterns based on the user need (that's the main difference between our grow led and the others).

I leave in Europe, so we have 230V here, so I had the idea to just put 4 in parallel (voltage drop but same intensity), but what happens for the 110V people ?

I spent weeks in this issue (finding the cheapest, safest design), cannot find an answer, so I decide to ask for help

Thanks

Niels