I feel like my problem may be stupidly simple.
Im just powering the arduino off of the USB connection here so it may not have the sufficient power to actually open the gate, so I'll hook it up to our 7805 again (problem now is heat dissipation) and see if I can't get it to work
I have to find a balance of how much amperage goes to each that keeps them cool since having things heat up is super counterproductive to our purpose
MOSFET's ain't BJT transistors. They do not require any significant amount of current.
Yup. If anything, try a little more voltage. That thing is rated up to 20V on the gate according to the datasheet, I think.
Yup.
[url]http://pdf.datasheetcatalog.com/datasheet/infineon/1-buz91a.pdf[/url]
[QUOTE=alexaz;44640883]MOSFET's ain't BJT transistors. They do not require any significant amount of current.[/QUOTE]
But in my experience, they need quite high voltage to open 100% or they just overheat :/
[QUOTE=Zero-Point;44640994]Yup. If anything, try a little more voltage. That thing is rated up to 20V on the gate according to the datasheet, I think.
Yup.
[url]http://pdf.datasheetcatalog.com/datasheet/infineon/1-buz91a.pdf[/url][/QUOTE]
Yeh, i agree, i would put around 12-15v in.
Yes they do need a higher voltage applied to the gate in general compared to a BJT due to the lower transconductance and high threshold voltage, it also directly relates to the Rds of the transistor with higher gate voltage giving lower Rds.
The gate current can be fairly high in switching applications since the gate capacitance has to charge and discharge, this gets worse at higher switching frequency.
Designing up a capacitor bank for 250 pcs of 450v 1500uF capacitors:
[img]http://i.imgur.com/vfm9Rqi.png[/img]
time to get friendly with the local sheet metal fabricator because im gonna need 50 of these things, then a frame to mount them all in.
[QUOTE=nuttyboffin;44648531]Designing up a capacitor bank for 250 pcs of 450v 1500uF capacitors:
time to get friendly with the local sheet metal fabricator because im gonna need 50 of these things, then a frame to mount them all in.[/QUOTE]
What's that program?
[QUOTE=ArgvCompany;44648578]What's that program?[/QUOTE]
Solid Edge ST6 using the student version for free rather then spend litterally £3000
[img]http://i.imgur.com/1mdXnxV.png[/img]
Re did it for 10 caps per sheet now.
[QUOTE=nuttyboffin;44648595]Solid Edge ST6 using the student version for free rather then spend litterally £3000
[img]http://i.imgur.com/1mdXnxV.png[/img]
Re did it for 10 caps per sheet now.[/QUOTE]
What are you going to do with the cap bank?
[QUOTE=metallics;44648609]What are you going to do with the cap bank?[/QUOTE]
Things like:
-Electromagnetic powered guns.
-Blows stuff up
-Smooth large powersupplys
-Sell them
[QUOTE=nuttyboffin;44648624]Things like:
-Electromagnetic powered guns.
-Blows stuff up
-Smooth large powersupplys
-Sell them[/QUOTE]
but mostly blow stuff up
[QUOTE=DrDevil;44648739]but mostly blow stuff up[/QUOTE]
Probably, who knows.
LCD display arrived. Hopefully this is going to be fairly easy to control with my Arduino.
[QUOTE=nuttyboffin;44648624]Things like:
-Electromagnetic powered guns.
-Blows stuff up
-Smooth large powersupplys
-Sell them[/QUOTE]
I was just wondering if you had something specific in mind!
[QUOTE=metallics;44649819]I was just wondering if you had something specific in mind![/QUOTE]
Not really to be honest. Maybe somthing like a 3-5kJ backpack style coilgun or somthing.
using a special made backpack and 2 big ass cables going to a hand held gun, kind of like ghostbuster's backpack.
Just keep in mind that capacitor banks can also blow up parts of your body with ease :)
[QUOTE=DrDevil;44650081]Just keep in mind that capacitor banks can also blow up parts of your body with ease :)[/QUOTE]
Oh yes, i do know that :) Luckly i have some rather nice welding cable with thick insulation, that and i don't do things half way. I plan to make my stuff very safe. (interlocks, plastic guards and emergency load dump.
[QUOTE=nuttyboffin;44650114]Oh yes, i do know that :) Luckly i have some rather nice welding cable with thick insulation, that and i don't do things half way. I plan to make my stuff very safe. (interlocks, plastic guards and [b]emergency load dump[/b].[/QUOTE]
Naughty.
Love the capbank plan 'boffin, good stuff. If you go down the coilgun/railgun/em-to-kinetic route, be careful with publishing any builds you do, anything pistol-sized that exerts over 8.1J of kinetic energy and anything larger that exerts 16.2J are legally classed as firearms.
Edit- Assuming flagdog isn't lying.
I'm going to order an IRL540 mosfet, since that is a logic level MOSFET it should be able to do its max of 28A at 5V, and since we're only putting in 6A I hope it will give off less heat and actually work
problem is I needed it several months ago and now need it yesterday
[QUOTE=paindoc;44664488]I'm going to order an IRL540 mosfet, since that is a logic level MOSFET it should be able to do its max of 28A at 5V, and since we're only putting in 6A I hope it will give off less heat and actually work
problem is I needed it several months ago and now need it yesterday[/QUOTE]
Recall that you can determine the heat sink required (if any) by:
Power_Dissipated = Rds * (I_load^2)
If its under the maximum power dissipated (according to the [URL="http://www.vishay.com/docs/91300/91300.pdf"]datasheet[/URL]), and given you are operating in a reasonable temperature range if the power dissipated is close to the max power, then no heat sink is required.
[URL="http://www.daycounter.com/Calculators/Heat-Sink-Temperature-Calculator.phtml"]Heat Sink Calculator[/URL]
Just had my transistors final today.
They combined a BJT first stage and Resistor-MOSFET 2nd stage to make an amplifier... It's like if it was designed to make our heads hurt.
[QUOTE=Angus725;44671069]Just had my transistors final today.
They combined a BJT first stage and Resistor-MOSFET 2nd stage to make an amplifier... It's like if it was designed to make our heads hurt.[/QUOTE]
Oh, one of [i]those[/i]...
My sympathies
Hey, guys, I need some help with the electronics on my bike. I noticed it was starting to struggle electrically (starter struggling, injectors/spark plugs struggling), so I checked the voltage on the battery and read a very sad 11.26V. When running, it would go up to 11.56 when I ran it [B]hard[/B]. I checked the voltage regulator in diode mode, it seemed to work, and gave me a ~.5 reading (ohms I'm guessing?) Then I checked the stator, which had 0 ohms between the phases, while idling, it showed a 6V between two phases (out of three)
So I guess my stator's fucked? What'd you think?
[QUOTE=Gulen;44677814]Hey, guys, I need some help with the electronics on my bike. I noticed it was starting to struggle electrically (starter struggling, injectors/spark plugs struggling), so I checked the voltage on the battery and read a very sad 11.26V. When running, it would go up to 11.56 when I ran it [B]hard[/B]. I checked the voltage regulator in diode mode, it seemed to work, and gave me a ~.5 reading (ohms I'm guessing?) Then I checked the stator, which had 0 ohms between the phases, while idling, it showed a 6V between two phases (out of three)
So I guess my stator's fucked? What'd you think?[/QUOTE]
Seems reasonable, if the battery was fucked then you'd still be getting a good voltage while running.
[editline]29th April 2014[/editline]
Also speaking of the recent talk of capacitors, I recently acquired a 1kg roll of copper wire (not sure what gauge but not very heavy) and I should get started on wiring up my ~100x avg 470uF 200V caps. The total bank should be just under 1kJ at 200V.
Then it's railgun time.
Oh great, since some retards keep blowing up stuff at our study, we'll not be allowed to use anything other than a benchtop power supply (as it has a limiter in it) to power a line-following robot :v:
I mean come on, the supply is like as big as the entire fucking robot will be! I'm not the one who blew up 4 motor shields (of which one was of the teacher) and an Arduino because they shorted it with an unlimited source of power. Hell, my entire project group managed to have no destructive short circuits at all during the entire project. Even[URL="http://i.imgur.com/NsN5DAP.jpg"] [I]this [/I] [/URL]didn't have any issues
I click on page 70 and I land on page 69, why is that?
Okay so it looks like we are likely to overheat our MOSFET since our RDS is 5v times 6A^2... or 180 watts. I can put a small stepper driver heatsink on it that I have laying around, but space is a huge constraint in our case, and putting it in our airflow is likely to heat the airflow countering the very thing we are trying to do in the first place.
However, if I have 2x 1A fans in series ahead of the peltier point, shouldn't this lower the total current in the circuit?
edit; or at least lower the current going to the MOSFET. its early in the morning and I haven't had coffee yet so im feeling a bit "special"
[QUOTE=paindoc;44686408]Okay so it looks like we are likely to overheat our MOSFET since our RDS is 5v times 6A^2... or 180 watts. I can put a small stepper driver heatsink on it that I have laying around, but space is a huge constraint in our case, and putting it in our airflow is likely to heat the airflow countering the very thing we are trying to do in the first place.
However, if I have 2x 1A fans in series ahead of the peltier point, shouldn't this lower the total current in the circuit?[/QUOTE]
5v has nothing to do with it. you need the Rds(on) which is 0.077 Ohms.
I believe the 5v you are refurring to is the Vgs which is the voltage used to drive the gate.
the correct math would be:
0.077*6^2 = 2.772W
3W then abouts. You will be just fine. I would stick a heatsink on it however.
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