| Electronics > Projects, Designs, and Technical Stuff |
| My constant current load - 90W , 3A 30V |
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| Harvs:
But they don't meet your voltage requirement :-// Anyway you've bought them now, so just make sure you don't exceed that 55Vds. I would still use separate control loops and forget about matching FETs. But that's you're choice, and I guess you've already got that board made and the single high powered resistor. BTW, I only talked about the IXFK230N20T because it was the cheapest FET that met your package requirements. By no means was that a one off case, it's just the cheapest I could find. |
| Spikee:
@ Harvs : Sorry for the confusion :P my specs are very loose ... i just made up some specs . I was very buzy whit a college project all week but today i had time to lasercut the front panel @ the FabLab in my school. (still have to sand of the exessive black marker ink. I should have selected higher power to engrave the text so it would be black but ... beginner fault :-// ) Pic: I still need to laser out some holes and make some extra markings , but it is a start. I have learned that seperate control loops and seperate load resistors is the way to go but i now have this pcb and i would like to use it. |
| Spikee:
--- Quote from: blackdog on November 29, 2012, 11:21:14 am ---Hi Spikee Buy 5 a 10 of these Fets: http://www.dickbest.nl/index.php?_a=viewProd&productId=2164 Select the fet's, see picture Kind regarts, Blackdog --- End quote --- The results: (had to put a few 1k pots in series to get 1A accuratly ...) https://dl.dropbox.com/u/100819959/mosfet%20scatter.pdf It won't be super accurate because the current would shift about. But i measured as good as i could. Fet 2 and 4 would be the best match. I will test the rest of my circuit in a few hours. gr. spikee |
| blackdog:
Hi Spikee, Fets 2 and 4 looks good :-) I know its a little drifty, thats wy i told you to mount the Fet on a heatsink. If i told you use 30V and 1.5A... No way, drift all over the place. You dit a fine job. Please let me see your final schematic. Kind regarts, Blackdog |
| Spikee:
i mounted it on the heatsink but they were still a bit drifting . The fan wasn't hooked up so i did a second test whit short on time and let the heatsink cool to the same temp. I got the same results =) . I just mounted the two fets and need to find a good spot to mount the resistor. I'm drawing a simple schematic for you. Output schematic: the gate resistor is mounted directly on the gate pin of the mosfet. Thanks spikee |
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