Electronics > Projects, Designs, and Technical Stuff
My constant current load - 90W , 3A 30V
Spikee:
So i had some more time and i worked on the constant current load.
I have fitted 4 IRFP064N on a Hyper z600 CPU cooler and used one opamp for each mosfet. As a load resistor i use 0.1 Ohm 3W now but i will be switching them for 8 W equivalents. I will be testing the supply whit a 200W load tomorrow. But i already peak tested it at 63A , 10V = +-630W but some wires , shunt wattage etc was to low to run it for longer than a 5-10 seconds. This setup should be capable of 200W whitout getting hotter than 50-60 deg C. using one 120mm fan which has an resonable CFM. I can fit another fan to improve it ... but i have to make the pcb first. I need to get some connectors so i can hook up my 750W coolermaster pc power supply and see what the max of this cooling setup is. I think it is about 300-400W and then it will probably be around 60-80 degrees C.
Sorry for the bad photo's / video my phone was empty and it is really late now ... but i'm just soo exited :o
Pic of setup:
https://dl.dropbox.com/u/100819959/constant%20current%20load/20130225_032839.jpg
Breadboard:
https://dl.dropbox.com/u/100819959/constant%20current%20load/20130225_032825.jpg
Feedback + gate wires:
https://dl.dropbox.com/u/100819959/constant%20current%20load/20130225_032828.jpg
Close-up of resistors , mosfet construction:
https://dl.dropbox.com/u/100819959/constant%20current%20load/20130225_033010.jpg
Todo:
-Make pcb
-Bigger wiring on some places
-Add intelligence (STM32 + touch screen lcd)
-total current measurement (LT6100 whit 2m ohm shunt)
-Put in an enclosure
- ...
blackdog:
Hi Spikee, :-)
How dit you connect the powerfets to the heatsink, glue?
Kind regarts,
Blackdog
LEECH666:
I've talked to Spikee on Skype some time ago. The FETs are indeed glued onto the heatsink with some thermal adhesive.
Spikee:
--- Quote from: blackdog on February 25, 2013, 11:51:20 am ---Hi Spikee, :-)
How dit you connect the powerfets to the heatsink, glue?
Kind regarts,
Blackdog
--- End quote ---
I used Arctic Silver thermal adhesive. That stuff is super strong , it's almost impossible to get it off without sanding the heatsink.
It conducts but that does not matter because all the drains are already connected whit wires. I'm making my schematic now in Altium and i will post it here. The fan puts alot of noise in the supply so extra schottky diode etc is advised. Without the schottky diode the output noise is around 20mV PP.
gr.spikee
63A peak current test:
A few moment before i had it at 50-60A for 20 seconds and the insulation of my wires was melting.
Schematic :
https://dl.dropbox.com/u/100819959/constant%20current%20load/Constant%20current%20EEVblog_Spikee.pdf
rbola35618:
Nice video and projects Spikee :-+.
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