jal3 Posted April 8, 2012 Report Share Posted April 8, 2012 http://www.irf.com/product-info/datasheets/data/irlb3034pbf.pdf Link to post Share on other sites
bjorn Posted April 9, 2012 Report Share Posted April 9, 2012 http://www.irf.com/product-info/datasheets/data/irlb3034pbf.pdf Seems to be OK. If I remeber correctly then it has high AMP rating and low internal resistance. Is there anything "not so great" I should know about this fet chip? Bjorn Link to post Share on other sites
jal3 Posted April 9, 2012 Report Share Posted April 9, 2012 Nothing special really. Works down to 4,5v and pulls m190 highspeed fine. Link to post Share on other sites
S.E.Pedersen Posted June 9, 2012 Report Share Posted June 9, 2012 Studying up on mosfets.. and I'm having a hard time locating the TVS diode (5KP18A) - from Terry’s design. I'm not supersteady in terms of elec.components.. but would a Schottky diode do the same job? - when we used brushed motors in radio controled cars - Schottky diodes was used to protect the ESC from voltage spikes,, (can I use this: https://www.elfaelektronikk.no/elfa3~no_no/elfa/init.do?item=70-149-62&toc=18839 ?) Link to post Share on other sites
hawaiianjuggernaut Posted June 10, 2012 Report Share Posted June 10, 2012 What about the drop in computerized ones? Like the burst wizard or the avocado. Doesnt that do the same thing? Link to post Share on other sites
Feyd Posted July 9, 2012 Report Share Posted July 9, 2012 I've read through the whole thread and I can't find anything on this... Put a standard non-AB fet together (design from the build a fet thread in the tech section just with an IRLB3034) and spent about 2 days playing on a test rig with it doing nada! Checked everything on it with a multimeter and all connections seem to be fine. Here's the odd bit, I saw a couple of pages back that gate/trigger resistor is not necessarily needed on this particular fet, tried without it and voila, works perfectly (in test rig, motor under no load)... Checked the resistor with the multimeter and it shows continuity... I do want to make some AB fets in the near future which I gather do need the G/T resistor, any ideas? I did have to use a 102Ohm resistor instead of a 100Ohm, could it be purely down to this? I'm not an electrical engineer, I know gearboxes but I can solder, any help would be much appreciated! Link to post Share on other sites
Paleblue Posted July 16, 2012 Report Share Posted July 16, 2012 I could not find any specific diagrams for building an AB FET for a P90, and did not want to make a new thread. So I scrounged up what I could find, and quickly made this. I am in all respects a newbie to FETs, but I can solder and have the general idea. Is my shoddy mspaint picture correct? :/ Link to post Share on other sites
Stinky Posted July 29, 2012 Report Share Posted July 29, 2012 That looks correct, if its the nearly the same as my Aug. The P90 has a 2 stage trigger? I have a question for Mosfet gurus. I made this mounting block for my mosfet, does it look ok? It goes in where this bit of metal was, which is not needed in the shorter front end. Its up in the sight about this deep Way back in the little recess in this next pic Does the tab need to be heatshrinked, will it be bad for the tab to come in contact with the inside of the potmetal sight on my mini AK? This bolt on the mount likely connects the tab to the sight electrically speaking, is that bad? Also, just made my first AB Mosfet, thanks everyone that ever posted a guide to that (I looked at ALL of them)! Works like a charm, stops the sector gear perfectly with the spring and tapet both uncompressed. Probably make one to replace this Mosfet, but it will have the same issue, so is it OK? I was hoping the sight would act as a heatsink until I built the AB Mosfet and learned the tab is connected to the drain pin! Link to post Share on other sites
Tommygunn Posted July 29, 2012 Report Share Posted July 29, 2012 What does that block do? Is it simply to take up the space and jam into the cavity to hold the mosfet steady? The only way the front sight, or any other metal work, will work as a heatsink is if you attach the mosfet directly to it. You ideally need to attach it to a flat, metal surface and sand any paint from the contact point then bolt/screw it down. If you have any 'thermal' paste/grease then all the better as it makes the thermal contact all the better. If your going to attach the mosfet to the metal work then you won't be able to add an overall sheath of heatshrink as you won't have a thermal contact point but as long as there is no risk of a short then there is no need to add the extra HS anyway. The tab is connected to the drain so as long as you don't have a strange short then it will be fine since it goes straight to the motor. Tom. Link to post Share on other sites
Stinky Posted August 9, 2012 Report Share Posted August 9, 2012 Thanks TG, its working ok, I think I am getting some heat dissipation from the metal nut soaking up some and transmitting it to the sight. Not much but a little bit. The evidence for this is that when I use a little block of aluminum I have as a soldering heatsink it really soaks up any heat in the FET quickly when I just rest it on top of the nut, even more when I press down sightly. I can feel the FET instantly cool down (squeezing with one finger on the FET other on the aluminum heatsink, FET cools from hot to touch to comfortable almost instantly after soldering). So since the nut is in contact with the metal sight, it must be drawing some heat... I hope. Its not necessarily needed for the 1404 FET but I figure every little bit helps. I have done ALLOT of overclocking and in that experience every bit of heat one can remove is a good thing. A few questions: Question 1 If I can hold the FET without burning my fingers, its gota be under 100c right? 100C is 212F, as 130F is generally considered the point at which fluids become to hot to touch for any amount of time. I suspect the FET's I make never get over 60C as I can touch them with discomfort but not burning my fingers during and directly after soldering. Is that low enough to ensure they are optimal or is 60C enough to degrade a 1404PBF or 3034PBF? Question 2, Just how tough is a IRL 1404PBF FET? Ummm.... I sort of used the wrong resistor for a bit... had remade a FET shorter and mistakenly soldered on a 33kohm 1/4watt where the 100ohm goes... Thing is the FET worked but had issues, to much resistance maybe? FET got hot quick and motor turned a bit slower then normal but still functional, like a weak 8.4v NiMH when running a fully charged 7.4v Lipo. Figured out what was wrong, actually just realized all of a sudden what I had done while washing dishes, fixed it, and the FET seems fine and the trigger response is back. It only had a few shots, maybe 15 actual piston cycles on the wrong resistor, any estimations on if this FET is OK or should I replace it? There is a 30A fuse, should I change that to a lower value to protect the LiPo in case the FET is bad? Would it matter? Question 3 (sort of Q1 continued) Re-soldering a FET, if I keep it under 60C during all soldering will it degrade a FET to be modified once or twice after construction? Link to post Share on other sites
Tommygunn Posted August 9, 2012 Report Share Posted August 9, 2012 Q1. If you can keep your finger on the fet then it is well within tolerance and there is absolutely nothing to worry about. Even if it was hotter, I don't mean sizzling, then it would still be ok. Obviously we are not talking support weapon continuous fire because then you would need to think about a copper or aluminium heatsink but for your average AEG burst fire you'll be fine with pretty much any suitable Mosfet. I don't have any additional heatsinking on my fet and it has an outer sheathing of heat shrink and I have never had a problem. Q2. Your Fet will be fine, don't worry about it as they are pretty tough suckers. Your 30A fuse is pretty high! The usual Amperage for a fuse is 15Amps. I have an IRF3808, 7.4V Lipos and 15Amp fuse which gives me 16rps. The mosfet is not heatsinked and I have the 15Amp fuse to act as my weak link in the system in case anything goes wrong. I'd rather blow a fuse than blow something more expensive. Q3. Again, don't worry about it but as with any soldering don't dawdle unnecessarily as damage may occur. The obligatory few seconds is all it takes. Tom. Link to post Share on other sites
Stinky Posted August 9, 2012 Report Share Posted August 9, 2012 Thanks again Tommygunn! I will go down to 15-20 amp fuses... Anyone want to buy some 30A fuses? Brand new never used! LOL jk I will of course feed them to my robotic cat. Link to post Share on other sites
LordElpus Posted August 15, 2012 Report Share Posted August 15, 2012 One item I hope a company will pick up on soon is a stripped down version of the Raptor/Stealth units which just replaces the trigger mech so you can use whatever fet unit you wish. Link to post Share on other sites
hawaiianjuggernaut Posted August 20, 2012 Report Share Posted August 20, 2012 Where do you guys buy all your parts for making your own fets? Link to post Share on other sites
SteevoLS Posted August 20, 2012 Report Share Posted August 20, 2012 I get mine from Newark or Digikey. Link to post Share on other sites
frogfish Posted August 20, 2012 Report Share Posted August 20, 2012 Got a quick question here, it appears as though my AWS Stealth fet keeps freezing on me. The weapon is cycling fine, everything is running well, the voltage on my lipo is good and near full charge, and after about 100 rounds through my weapon I get nothing, no attempt to cycle, just as if the mosfet had died, I wait about a half an hour, try to cycle it again and presto all is a-ok for another hundred or so rounds. Anyone have any advice, I'm frustrated enough that I want to tear th damn thing out, but I like the trigger unit in there as I have yet to find a good V2 replacement for my VFC MK17 trigger (the VfC one is *suitcase*). Link to post Share on other sites
hawaiianjuggernaut Posted August 21, 2012 Report Share Posted August 21, 2012 are diodes interchangeable? what is a minimum needed? ive been doing my research all day on fets. im thinking about building my own. i found places where you can get the IRL1404 fet units for like $1.50 apiece and the resistors for $6.32 for 500. (bulk pricing! yaaay) 5kp18a is the diode, its rated for 18v at 5000 watts, is that high needed for a 25c 11.1 current? are lower rated ones okay to use?? golly fets are confuzzlin Link to post Share on other sites
Stinky Posted August 25, 2012 Report Share Posted August 25, 2012 Got a quick question here, it appears as though my AWS Stealth fet keeps freezing on me. The weapon is cycling fine, everything is running well, the voltage on my lipo is good and near full charge, and after about 100 rounds through my weapon I get nothing, no attempt to cycle, just as if the mosfet had died, I wait about a half an hour, try to cycle it again and presto all is a-ok for another hundred or so rounds. Anyone have any advice, I'm frustrated enough that I want to tear th damn thing out, but I like the trigger unit in there as I have yet to find a good V2 replacement for my VFC MK17 trigger (the VfC one is *suitcase*). Sounds like a poly fuse overheating and resetting. I think the AWS Stealth has some integral current regulation and an over current fuse. I think it is shutting down for Amp/heat reasons. What spring and motor and gear ratio? Link to post Share on other sites
frogfish Posted August 25, 2012 Report Share Posted August 25, 2012 Not entirely sure, its the stock gears, whatever ratio those are, a high torque motor, and an sp120 equivalent. Thats what I was thinking too, but I have very little EE experience, would changing the motor or spring help out? Link to post Share on other sites
original poster Posted August 28, 2012 Report Share Posted August 28, 2012 Going to pick up an ASCU V2 at some point, bring on 3 round burst Link to post Share on other sites
Mr Teatameh Posted August 28, 2012 Report Share Posted August 28, 2012 Not entirely sure, its the stock gears, whatever ratio those are, a high torque motor, and an sp120 equivalent. Thats what I was thinking too, but I have very little EE experience, would changing the motor or spring help out? Hi Frogfish I have the AWS Raptor in my SCAR-H SSR and had lock up problems and what seemed to be "short battery life" - I replaced the VFC stock high torque motor with a Lonex A2 Infinite Torque-Up (Long) motor and it seems to be much much better. Couple of caveats though: 1. The VFC motors are slightly shorter than standard (sigh), but you can sand the plastic base housing on the Lonex one to allow for some adjustability with the motor height screw. 2. I'm not 100% this will cure your problems, as mine was locking during cycle rather than refusing to start a cycle at all, so this "cure" would be a bit of a "punt/gamble". Oh I'll PM you some CAD drawings I've been working on in anticipation of my CNC machine arriving, you might be interested in (I've given up waiting for WE ;-) ). Link to post Share on other sites
frogfish Posted August 30, 2012 Report Share Posted August 30, 2012 Thanks for the tip, I'll give it a try but as is I don't think I'm running a VFC motor... can't rememebr for the life of me. Its very frustrating as the mosfet is great, and the weapon is as well, but they just don't seem to want to work together.... Would love to see your cad drawings, I too have given up hope if you are talking about what I think you are. Link to post Share on other sites
Kamigawa Posted November 11, 2012 Report Share Posted November 11, 2012 Hi, quick question: I have a Dboys AKS-74U and a VFC AK-74 that I want to install mosfets in. I was originally planning to make the mosfets myself, but I just realised that it will be too time-consuming for me. I want the most basic kind of mosfet as I have no need for 3-round bursts or active breaking. Will any of these do? - http://www.wgcshop.com/wgc2008/main/product_detail1.php?search_From=searchItem&item=AZI-MOSFET-T1&search=special&rs=mosfet&catid=&cat= - http://www.wgcshop.com/wgc2008/main/product_detail1.php?search_From=searchItem&item=AZI-MOSFET-T2&search=special&rs=mosfet&catid=&cat= - http://www.wgcshop.com/wgc2008/main/product_detail1.php?search_From=searchItem&item=AIP-EU-AK&search=special&rs=mosfet&catid=&cat= Link to post Share on other sites
infected Posted November 12, 2012 Report Share Posted November 12, 2012 I've never used those before, but you could always order from us too. I am biased, but you don't really know what parts you're getting in these HK manufactured units. Yeah, shameless plug but we've been doing this for a long time and you'll find a lot of people running our mosfets happily. http://www.infectedarmory.com/mosfets.html Just my .02 Link to post Share on other sites
Zero2Fear Posted November 13, 2012 Report Share Posted November 13, 2012 I got a quick question... I've been running a Raptor V2HC-120X in my G&P M4 EOD for a year now and I'm using Firefox 7.4v 1200mAh LiPo's.. Now I'm wondering if this mosfet also makes me use 11.1v 1200mAh (15-20C) LiPo's and that it doesn't destroy my gearbox/piston/motor etc. My G&P has a standard gearbox/piston/motor, only barrel/hopup has been changed. If yes, that's great If no, what can I change to have this 11.1v ready? (reinforced piston, reinforced gears?) Did some research already but couldn't find any detailed information about this subject. Maybe someone can help me out? Much appreciated. Link to post Share on other sites
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