Electronics > Projects, Designs, and Technical Stuff
My constant current load - 90W , 3A 30V
<< < (18/19) > >>
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.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod