[QUOTE=LoneWolf_Recon;51886687]
With this you can probably ditch the 100uF cap I mentioned earlier and stick with just the decoupling cap. However I recommend keeping the base resistors in the off chance that the gate ruptures and current flows from your 12V line to your 5V logic.[/QUOTE]
Couldn't he just add some diodes on the 5V logic lines in that case?
[QUOTE=Zero-Point;51887157]Couldn't he just add some diodes on the 5V logic lines in that case?[/QUOTE]
But then he wouldn't be able to pull the lines low if he needed to turn off a particular solenoid.
[QUOTE=LoneWolf_Recon;51887176]But then he wouldn't be able to pull the lines low if he needed to turn off a particular solenoid.[/QUOTE]
If he's using MOSFETs, he just needs a pull-down resistor on the gate, doesn't he?
[QUOTE=Zero-Point;51887187]If he's using MOSFETs, he just needs a pull-down resistor on the gate, doesn't he?[/QUOTE]
Yeah you're right. So Goz3rr, if you want to make it super skookum, replace the TIP120 with the above mosfet, replace the base resistors with signal diodes (like 1N4148), and add pull down resistors to the gate of each mosfet.
But replacing the TIP120 with the MOSFET will also work.
Alright thanks for all the pointers guys, So I'd end up with something like this connected to each output of the 74HC595 correct?
[img]https://i.imgur.com/7yfnwJk.png[/img]
Looking around the internet there's some circuits where the solenoid is powered with a lower voltage after moving to reduce power consumption, is that something worth looking into when these solenoids will be held for a couple of seconds at most?
Or maybe just use PWM? If it makes noise that doesn't really matter, as long as they stay in roughly the same place for the time they're on.
Basically we're making a paper punch for player piano rolls, the solenoids only need to move a small part under the big punch and hold them there while the note is pressed.
My friend picked out 12V 2A solenoids, but I feel like we can probably get away with smaller ones since they don't really need much power at all.
[QUOTE=Goz3rr;51884460]I need to control couple of dozen solenoids (not sure on what kind yet, probably 12V 2A or 5V 1A), would a bunch of PCBs like this chained together work or am I doing something stupid?
Only a few of them will be on at once but they might be held for a few seconds at a time. I've checked the max current the 74HC595 can provide (70mA total, 25mA per pin) which shouldn't be an issue with the TIP120 having a DC Current Gain factor of 1000
[img]https://i.imgur.com/1uKpuPX.png[/img][/QUOTE]
Looks good to me, a few things to consider:
pull down resistors on all transistors.
pull up/down resistors on the bus line, else it's going to go havoc with any lost connections etc.
I favour using low cost microcontrollers (STM32F0 for example) cheap as chips and you can do RS485 comms which are seriously rugged.
So for my electronic engineering course I have to rewrite my already 200 line C++ program from a previous lab which can do addition and subtraction to add 70-80 more lines of complexity because "you must use inheritance" regardless of whether or not it's actually useful lol.
That said I'm finishing off my PCB design for an RFID reader and because Southampton are awesome they'll have them made for us and let us build and test them.
[SP]Is electronics/programming stuff acceptable in here as well?[/sp]
[QUOTE=NeonpieDFTBA;51898374]So for my electronic engineering course I have to rewrite my already 200 line C++ program from a previous lab which can do addition and subtraction to add 70-80 more lines of complexity because "you must use inheritance" regardless of whether or not it's actually useful lol.
That said I'm finishing off my PCB design for an RFID reader and because Southampton are awesome they'll have them made for us and let us build and test them.
[SP]Is electronics/programming stuff acceptable in here as well?[/sp][/QUOTE]
Are you undergrad? Because its kinda nice to get your own PCB fabbed by the Uni, I was only able to do that through the Uni (not on my own time) in Senior year shipped off to OSHPark.
(Also the mill we had on campus was garbage, didn't use gerbers and had to load designs over compactflash because it was an old piece of shit)
[QUOTE=NeonpieDFTBA;51898374]So for my electronic engineering course I have to rewrite my already 200 line C++ program from a previous lab which can do addition and subtraction to add 70-80 more lines of complexity because "you must use inheritance" regardless of whether or not it's actually useful lol.
That said I'm finishing off my PCB design for an RFID reader and because Southampton are awesome they'll have them made for us and let us build and test them.
[SP]Is electronics/programming stuff acceptable in here as well?[/sp][/QUOTE]
Oh cool, you're up at Southampton?
I'm based down in Bournemouth doing the HNC Course!
[QUOTE=LoneWolf_Recon;51899120]Are you undergrad? Because its kinda nice to get your own PCB fabbed by the Uni, I was only able to do that through the Uni (not on my own time) in Senior year shipped off to OSHPark.
(Also the mill we had on campus was garbage, didn't use gerbers and had to load designs over compactflash because it was an old piece of shit)[/QUOTE]
1st year undergrad, they're sending it off to a manufacturer I think. One of the reasons I came here is the funding the department has and the fact they place a lot of emphasis on actually doing and testing things rather than just theory.
The microwave oven that's in my apartment broke down and the landlord said I can get rid of it. My question is what could I do with the parts from the microwave oven?
A quick search for "microwave oven transformer projects" on Google only gives stick welders and the like, but I'm sure you could do a lot more interesting stuff with what's inside. Any ideas?
[QUOTE=supervoltage;51940379]The microwave oven that's in my apartment broke down and the landlord said I can get rid of it. My question is what could I do with the parts from the microwave oven?
A quick search for "microwave oven transformer projects" on Google only gives stick welders and the like, but I'm sure you could do a lot more interesting stuff with what's inside. Any ideas?[/QUOTE]
ghetto tesla transformer?
[QUOTE=supervoltage;51940379]The microwave oven that's in my apartment broke down and the landlord said I can get rid of it. My question is what could I do with the parts from the microwave oven?
A quick search for "microwave oven transformer projects" on Google only gives stick welders and the like, but I'm sure you could do a lot more interesting stuff with what's inside. Any ideas?[/QUOTE]
Aside from the transformer, HV caps and rectifiers there isn't much of use, I probably don't need to tell you but I'll do so anyway, don't play with the the high voltage unless you want to be a smoking corpse, don't touch the magnetron either as it usually contains toxic beryllium oxide.
[QUOTE=Van-man;51940542]ghetto tesla transformer?[/QUOTE]
Not with a MOT, unless he happens to already be quite experienced in dealing with high voltage.
A Tesla transformer sounds fun, I was always interested in those things but I'm most afraid of the high cost it may involve. Thankfully I'm aware of the dangers of high and extremely high voltages to be safe around these things, although I have limited experience (only four years of ghetto Romanian high school centred around electrical installations).
I'm all ears if someone can come up with an interesting project that's more than just metal melting.
[QUOTE=supervoltage;51940955]A Tesla transformer sounds fun, I was always interested in those things but I'm most afraid of the high cost it may involve. Thankfully I'm aware of the dangers of high and extremely high voltages to be safe around these things, although I have limited experience (only four years of ghetto Romanian high school centred around electrical installations).
I'm all ears if someone can come up with an interesting project that's more than just metal melting.[/QUOTE]
Really most HV projects are achievable through MOTs ([URL="http://www.pocketmagic.net/rewound-microwave-oven-transformer/"]Provided that you change the turns ratio[/URL] or use a [URL="https://www.amazon.com/PHC-Enterprise-Variac-Variable-Transformer/dp/B006NGI8VS"]Variac[/URL] before the primary winding). You can use them to power all sorts of gas discharge displays/lamps like [URL="https://threeneurons.wordpress.com/nixie-power-supply/"]Nixie Tubes[/URL] (Provided that its been rectified using the microwave oven diodes), generate the bias voltage for [URL="http://uzzors2k.4hv.org/index.php?page=sbm19blugeiger"]geiger-muller tubes[/URL] (Again, provided that its been rectified) or hell even make an ion accelerator for use with Sputtering to make cool metallic or conductive coatings on glass or other substrates:
[video=youtube;c4Sic1DRXJI]https://www.youtube.com/watch?v=c4Sic1DRXJI[/video]
But yeah, all of this stuff can and will kill you if you are not careful.
That's all cool stuff, but I dunno, I may just repurpose the copper wire inside and build smaller coils for other applications. Of course, I'd only unwind it when it'd be necessary, however given my amazing amounts of motivation I probably won't end up doing anything anyway.
You could also rewind the transformer for low voltage, high-current applications. Not necessarily stick/spot welders, but possibly rectified high-current DC supplies.
[QUOTE=Zero-Point;51942221]You could also rewind the transformer for low voltage, high-current applications. Not necessarily stick/spot welders, but possibly rectified high-current DC supplies.[/QUOTE]
So a melty melty burny burn thing with the abilty to use a carbon rod to make a arc lamp? Or just something more simple minded?
[QUOTE=andreblue;51943216]So a melty melty burny burn thing with the abilty to use a carbon rod to make a arc lamp? Or just something more simple minded?[/QUOTE]
With sufficient insulation, you could make an arc furnace, as well.
I'd say you could also [I]technically[/I] use it to spot-weld tabs on battery packs but that would be over kill [sp]in that it would mean immolating every battery you try it on[/sp]. :v:
I rewound an old MOT pulled from a 230V microwave at my old job, was planning on making a spot-welder because the one we had at the shop really sucked ass, though I never got around to it. My boss said he didn't like the idea of me playing with such high voltages, even though I calculated and measured the output to be a mere 5-6V. (but then this is the same guy who once argued with a service tech that you should have continuity between the primary and secondary windings on a transformer)
I'm working on a little game project with a few mates and and one of them sent me their part to integrate into the main program. It threw a billion errors when I tried to compile it so I asked:
[QUOTE=I]You did compile this to check for errors, right?[/QUOTE]
[QUOTE=My 'Friend']No...[/QUOTE]
At least it didn't take long to transfer, right?
Well that sucks. I've been looking to make a power supply for some servos that drops the 8.4V from my LiPos to 7.2V, which my servos would run a little better at. (not necessarily better, but definitely cooler I'd imagine :v: ).
I thought I could use these LM723CN's I got from some old circuit boards, but their min. in-out differential is 3V. :disgust:
Wonder if I could get away with just using a bunch of high-current diodes in parallel...
*Edit/Update*
Decided to try and see if these MG996 servos could handle 8.4V without need for dropping it down. It certainly would be handy if it could. So I set up my bench-top to output 8.4V, confirmed with the meter, then set up my arduino to just turn it from 10-170 degrees every half-second. (stress test!)
Things I noticed:
This thing likes to over-shoot. Jitters, too. Definitely going to have to replace the control boards in these if I'm going to use them for robotics use.
The case definitely gets a bit warm, around 30-32C according to my crappy temp probe.
After less than a minute of testing in these conditions, the motor stopped turning in one direction, then stopped turning altogether, drawing 4A. Oops. :v: (RIP test servo, 2016-2017) Good thing I got more than I'd need (30).
And after the test though, the motor measured at about 40C. RIP motor?
The control board didn't seem the least bit warm, so I'm inclined to think it functions just fine after all this.
After replugging the servo to see if it was just an over-temp safety, the motor turned a tiny bit, then stopped. Opened it up, and out came the smoke. Not from the motor, not from the board, but from the pot. I'm curious what sort of current load they have going through a feed-back pot to allow it to burn up like that...
Though upon further investigation, turns out one of the [url=https://www.fairchildsemi.com/datasheets/FD/FDS4953.pdf]MOSFET packages[/url] did in fact burn. Which is strange, as they're rated at 30V at 5A.
On a positive note, I was planning on replacing these control boards anyway, as the goal was to make a humanoid robot with them, and standard servo controls wouldn't cut it. (was looking into OpenServo, but it appears to be dead ATM)
Testing without the board shows that these little motors will happily take 8.5V, not sure if I want to crank it to 10 or 12V to see if it will handle those as well, for though they might, I don't have an adequate means of testing them under load, but they're torque-y as all get-out as I cannot stop them with my hand.
I sure love how extruded metal enclosures can make any project look professional. \:v:/
[IMG]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/IMG_7134.jpg[/IMG]
[t]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/IMG_7340.jpg[/t][t]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/IMG_7345.jpg[/t]
[t]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/IMG_7353.jpg[/t][t]http://i11.photobucket.com/albums/a166/ballsandy/Computer%20related/IMG_7358.png[/t]
My home built OBD1 ALDL to USB interface is finally done. Too bad the developer of the Rhinoview software is mad pissed at me for basically figuring out I can circumvent how the latest version of software requires you to buy his "custom" USB dongle.
His response to my effort was accusing that I was stealing his software. :what:
Custom my ass. When he took his software out of beta he removed the ability to read data from physical serial ports [del]and instead relies on an FTDI chip using their DLL[/del] (edited: There's an additional check he's added, so you HAVE to buy his dongle). Because of me he's pulled down any hint of his software being freely available and his adapter designs being also publically available. Cunt, your secret is out. :v: :v: :v:
[editline]asdsa[/editline]
That didn't stop me from downloading two different versions of his beta software, one version of this recent software before I disclosed the flaw and several screengrabs dating back half a decade of him posting his designs and saying it was all free to use.
Slightly related to extruded cases, I recently stumbled across one of Mike's handy suggestions for creating panels for extruded cases:
[video=youtube;Yj0Bv4UEFSs]http://www.youtube.com/watch?v=Yj0Bv4UEFSs[/video]
It's always pissed me off to no end how I can scribe, countersink, drill and STILL end up with shit that's not perfectly straight.
[QUOTE=pentium;51957259]It's always pissed me off to no end how I can scribe, countersink, drill and STILL end up with shit that's not perfectly straight.[/QUOTE]
get something cnc based, like a nice little thing like this [IMG]http://spectracore.com/Merchant2/graphics/00000001/Motorized_Slide_Guide_XY_Axis_Stages/KYS18300_N10_J_p.jpg[/IMG]
[QUOTE=pentium;51957259]It's always pissed me off to no end how I can scribe, countersink, drill and STILL end up with shit that's not perfectly straight.[/QUOTE]
[media]https://www.youtube.com/watch?v=QhpOg186fks&t=0s[/media]
[QUOTE=pentium;51957259]It's always pissed me off to no end how I can scribe, countersink, drill and STILL end up with shit that's not perfectly straight.[/QUOTE]
Always start drilling with a very small bit, like 3/32" and work up to the actual size in a few increments, even when using a center punch.
So I'm modifying a switching power supply which is rated to put out 13V @ ~10A. I'm making the voltage variable from about 0 to 20 and adjustable current limiting. After hours of tests I'm finding out that it's just too unstable from 0 to ~1V unless I load it down with a fairly low value resistor. The problem with that of course is as the output increases, that resistor will start dissipating tons of power.
Anyone know of a way to deal with that or am I just asking too much out of this thing?
Just put a simple SPDT switch before the resistor that you flip after 1v to bypass the resistor. It's not 100% ideal, but it'd solve the problem I suppose, and it's probably the cheapest way to do so.
I've got a 9V AC/DC Chinese adapter that I can't open and am wondering what's inside.
I've tried using a mains detection screwdriver on the output (didn't light up)
Measured the voltage between ground (earth on the wall socket) and output, was 9V
Measured resistance (while unplugged obviously) between input and output pins, seems to be infinite
I'm pretty sure this means it at least has a transformer in there (and not a capacitive dropper). I'm not too concerned about it blowing up because I'll only use it when present, more about getting shocked from accidentally touching something connected to it (i.e arduino) because it's at mains potential
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Electrical Engineering V3
