| Electronics > Projects, Designs, and Technical Stuff |
| My constant current load - 90W , 3A 30V |
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| grenert:
Jay_Diddy_B, Did that case come with the heatsink? Where did you find it? Thanks! |
| Spikee:
--- Quote from: rbola35618 on February 26, 2013, 01:31:03 pm ---Nice video and projects Spikee :-+. --- End quote --- Thanks! --- Quote from: grenert on February 26, 2013, 03:20:48 pm ---Jay_Diddy_B, Did that case come with the heatsink? Where did you find it? Thanks! --- End quote --- He used an off the shelf case. Got a metal plate the same size as the normal end cap. Drilled some mounting holes in it and mounted the heatsink on the plate. |
| Jay_Diddy_B:
Hi Grenert, Spikee is correct. Here are the details: The case was manufactured by Hammond part number 1598A. The rear panel was cut from aluminum sheet 0.062, 1.5mm. The Heatsink was cut from a length of aluminum extrusion. It is about 1 inch (25mm high) I drilled and tapped the heatsink to attach it to the metal plate. This design is good for about 10W dissipation. Regards, Jay_Diddy_B |
| clcham:
--- Quote from: Spikee on February 25, 2013, 02:55:32 am ---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 - ... --- End quote --- Hi Spikee, I've seen your schematic, I have a few questions: 1) why do you need a pull down resistor? 2) there is a 2.7k resistor in the feedback path, what is it for? 3) what is the maximum voltage capable of discharging with this design? thanks |
| Spikee:
1. So the mosfets turn off when you apply no current. 2. Probably some kind of filter (haven't looked at schematic , there is probably also a cap somewhere) 3. It is limited by the voltage of the mosfet. The IRFP064N has a VDSS = 55V . If you need more then you need to change the mosfet. |
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