#robotics Logs

Apr 19 2013

01:26 Jak_o_Shadows done a fair bit of my electronics design
01:26 Jak_o_Shadows http://imagebin.org/254562 is the bare uC
01:26 Hukka Gonna buy parts for a new club today
01:28 SecretFire Jack_o_shadows : I don't really know much about robotics, but it really interests me. Im going for my degree in computer science. Does robotics entail a lot of programming?
01:31 Hukka Depends what you want to do
01:31 Hukka If you use only remote control, you might not need any programming at all
01:31 Hukka If you make a software agent, it's pure programming
06:20 dunz0r Jak_o_Android: That drawing looks fine, but are you going to control the motor with just one wire?
06:21 dunz0r And you can't drive a motor with an mCU. You need a transistor or relay at least. An mCU can't supply the current needed.
06:22 Triffid_Hunter dunz0r: he has a very nice h-bridge driver chip and some power mosfets
06:22 dunz0r Ah. Good :)
06:22 dunz0r I wonder what sort of fancy design you can drive with just one pin. I would be interested in looking at something like that.
06:23 dunz0r A seperate mCU and some sort of serial protocol maybe?
06:23 Triffid_Hunter dunz0r: hip4082
06:23 Triffid_Hunter dunz0r: needs two lines, but if you give them an inverted signal you can just provide locked antiphase from the mcu on one line
06:24 Triffid_Hunter it's a lovely chip.. allows independent control of each mosfet, but also has built-in shoot through protection and dead time so you can just tie the high side mosfets to +ve and control the whole lot from the low side inputs
06:24 dunz0r Ah... I see how it works now, two PWM lines.
06:24 dunz0r I've built an H-bridge which works like that :)
06:25 Triffid_Hunter poor guy was trying to untangle the intricacies of h-bridge design as a first project
06:25 dunz0r http://hax0r.se/files/img/electronics/H-bridge-board.JPG and http://hax0r.se/files/img/electronics/h-bridge_01.png
06:26 Triffid_Hunter dunz0r: heh https://picasaweb.google.com/lh/photo/Q6cjAftoBdGhgy1Gl4iuydMTjNZETYmyPJy0liipFm0 is mine ;)
06:26 dunz0r Should've doublechecked the design etc, it's a fairly stupid placement of components etc, but it was my first PCB ever, so I don't feel that bad. It didn't even catch fire(yet)
06:26 Triffid_Hunter ah nice
06:26 Triffid_Hunter yeah some things come only with experience :)
06:27 dunz0r Triffid_Hunter: Like choosing the right footprint for capacitors and not placing them so close that you have to "raise" some of them :)
06:27 Triffid_Hunter I've been stocking up on 0603 smd
06:27 nz0r
06:28 dunz0r My next project will be completely SMD, apart from crystals and such.
06:28 Triffid_Hunter big enough to manipulate by hand, small enough for some really tiny boards. also fits perfectly between 0.1" pin spacing
06:28 Triffid_Hunter dunz0r: why crystals? plenty of smd crystals out there
06:28 Triffid_Hunter got a few projects around with crystals that look like they'd almost fit in an 0805 footprint
06:28 dunz0r Triffid_Hunter: I have so many throughhole-crystals, so it's sort of a waste to buy new ones, they're not that big anyway.
06:28 Triffid_Hunter fair enough
06:29 dunz0r Probably an STM32F100(ARM mCU) and two DRV8801(H-bridge from TI) on my next build.
06:29 Triffid_Hunter my esc doesn't have any crystal at all, uses the '328's internal R/C osc
06:29 dunz0r 8MHz is enough for most applications :)
06:30 Triffid_Hunter yup definitely
06:30 dunz0r I use a bootloader on my projects that require a 16MHz crystal, otherwise I probably wouldn't bother.
06:30 Triffid_Hunter optiboot should be able to recompile for any core clock
06:31 Triffid_Hunter and all the cortex-m cores have PLLs anyway and start with internal R/C osc so can run those at basically any speed.. just need a crystal if you want accurate timing
06:31 dunz0r Got a bunch of Atmega328s with the Arduino bootloader preburned with crystal and load capacitors for a good price, hence too lazy to switch bootloader.
06:32 dunz0r I'm interested in trying out another one though, would be nice to use a 20MHz crystal.
06:32 Triffid_Hunter my arduino has a 20MHz crystal
06:32 Triffid_Hunter I upgraded it. it's also capable of running on 3.3v thanks to a little rewiring
06:33 dunz0r Triffid_Hunter: Oh? Maybe the bootloader has been update or something, read something about the bootloader not being able to use 20MHz crystal.
06:33 dunz0r *updated
06:33 Triffid_Hunter dunz0r: well no, because changing a number in the bootloader source is too hard for most arduino users
06:34 dunz0r Hehe, probably.
06:34 Triffid_Hunter you can't just switch the crystal and expect it to work, it won't notice the different clock. have to make a new bootloader for the new clock and flash it in with a spi programmer
06:34 dunz0r I don't really have a reason to use a 20MHz crystal and I would have to recalculate all my timers... I'll do it the next time I build with a 328.
06:35 Triffid_Hunter yeah, the '328 in MLC package is good fun (leftmost chip in my ESC picture)
06:35 Triffid_Hunter like the qfn you get A6 and A7 brought out to pins
06:35 Triffid_Hunter so basically two extra ADC inputs for free vs the dip used on the arduino
06:35 dunz0r Too bad they're just ADC-pins, wouldn't mind two more GPIO :)
06:36 Triffid_Hunter yeah there is that, I've no idea why they didn't hook them to PC6/PC7 internally, that would have been great
06:36 Triffid_Hunter re timers, I always calculate against F_CPU or put a huge warning
06:37 dunz0r Triffid_Hunter: Hmm, that's a good idea actually.
06:37 Triffid_Hunter let the preprocessor sort it out
06:37 Triffid_Hunter as long as all the numbers are static and known at compile time, it just renders down to a final number and sticks that in the binary
06:37 Triffid_Hunter that's how my fastio macro system works
06:38 Triffid_Hunter dunz0r: https://github.com/triffid/ESC/blob/master/arduino.h#L29 <-- boils all GPIO access down to a single sbi/cbi (2-cycle) instruction
06:38 dunz0r Got most numbers as preprocessor-things actually. Not timer values though, but for this project, the clock frequency won't change, so I'll leave 'em :)
06:38 Triffid_Hunter and all you lose is runtime pin remapping which no-one uses anyway
06:39 dunz0r I use "regular" AVR-C, so it boils down to two instructions for me anyway :)
06:39 dunz0r http://git.hax0r.se/?p=AVR/.git;a=blob;f=Minisumo2013/main.c
06:39 Triffid_Hunter sure, I prefer blah = READ(PB6); over blah = (PORTB & _BV(PB6))?1:0 though, even if the binary is identical
06:40 dunz0r I tend to use "PINB & (1 << PB6)"
06:41 Triffid_Hunter yeah _BV(a) == (1 << (a))
06:41 Triffid_Hunter although I usually reimplement it as MASK() since _BV is sinful ugly
06:41 Jak_o_Shadows yeah, I have an inverter, was hoping to use that.
06:42 Triffid_Hunter Jak_o_Shadows: yep, it works great as long as your PWM frequency is high enough that the motor's inductance dominats
06:42 Triffid_Hunter dominates*
06:42 Jak_o_Shadows beautiful
06:42 Jak_o_Shadows I hope that's true
06:42 Triffid_Hunter Jak_o_Shadows: google "locked antiphase"
06:43 Triffid_Hunter Jak_o_Shadows: not sure if you've realised, but with that drive method you get powerful braking as well as propulsion
06:43 Triffid_Hunter it strongly compels the motor to move at a set speed
06:43 Jak_o_Shadows not sure if you've realised, but i heavily lack the theory to be doing this.
06:43 Triffid_Hunter Jak_o_Shadows: not for long ;)
06:44 Jak_o_Shadows but yeah, I just need to finalise the component values I want to use, then i'm good.
06:44 Triffid_Hunter Jak_o_Shadows: fwiw I think you're learning in the most effective and efficient way possible. you have a project, and you're picking up the required knowledge as you go
06:45 Triffid_Hunter that's how I got where I am, and my knowledge is profoundly more crosslinked and grounded than even the professional microelectronics engineers I've met
06:45 Jak_o_Shadows Got a slight problem is that the motor is 16V, the uC is 5V (or 3.3 really, but it can the dev board can go down from 5), but the max the hip 4082 wants for it's voltage thing (AHI/BHI) is 15
06:45 Jak_o_Shadows Yeah, that's mostly how I learn projects
06:45 Jak_o_Shadows dive in, struggle, finish, redo
06:46 Jak_o_Shadows About a quarter of the way down http://www.projectsinterestsandetcetera.com/conestoga-pages-from-lockeblog/ , is how I plan on doing my bump sensors.
06:46 Triffid_Hunter ahi/bhi are logic inputs. they work down to 3v (Vih is 2.5v from memory)
06:46 Triffid_Hunter so tie them to your +5v instead
06:47 Jak_o_Shadows The datasheet implementatoin shows them as +12V, I thought that was the voltage you were telling it to use for the mosfets?
06:48 Triffid_Hunter anything between 2.5v and 15v will work
06:48 Jak_o_Shadows If i'm using 16V for the motor, I want as close to that as possible, for the mosfets health?
06:48 Jak_o_Shadows How does the HIP4082 know what voltage to output to the mosfets?
06:48 Triffid_Hunter Jak_o_Shadows: the AHI/BHI are logic inputs, they have nothing to do with the mosfets. the chip is responsible for providing suitable drive for the mosfest
06:49 Triffid_Hunter Jak_o_Shadows: it feeds whatever the supply voltage is
06:49 Triffid_Hunter make sure it's not above 20v, mosfets don't like that ;)
06:49 Triffid_Hunter if in doubt, 7815 or similar
06:49 Jak_o_Shadows Luckily, I have a spare 7 mosfets.
06:52 Jak_o_Shadows Am I confusing this with pin 12, Vdd?
06:52 Triffid_Hunter yeah possibly
06:53 Triffid_Hunter basically if AHI is >2.5v, and ALO is <1v then the high side mosfet is turned on
06:53 Triffid_Hunter sorry, AHI/ALI
06:54 Triffid_Hunter ALO is the low side gate drive, getting my terms mixed up :/
06:56 Jak_o_Shadows either way, I think I now know what i'm talking about, so we're good
06:56 Triffid_Hunter :)
06:57 Jak_o_Shadows I just need to look at a couple more things, pick some component values, plan the breadboard and protoboard, get the servos, solder and program
06:59 Triffid_Hunter I took my R/C out for a spin today.. still have the current dialed up a bit high, my current sense resistor keeps burning
06:59 Triffid_Hunter better that than the mosfets I suppose!
06:59 Jak_o_Shadows yeah.
07:00 Jak_o_Shadows Luckily, I planned in failure, and I have a backup plan. Buy stuff online early, coming near my personal deadline, but stuff locally for 3x the price
08:24 SquirrelCZECH hi folks! :-)
08:27 Hukka Hi
19:08 theBear nice ! buddy found a noname hd lcd, maybe 34" or so, on the side of the road, was backlight-cycling.... little fiddle and reroute of the hv cables, it's working perfectly :)
20:45 GuShh_ aww
20:45 Shh_ hands theBear some pop
20:45 Shh_ just did a kludge job on a brass solenoid valve that broke in half -- decided to solder it back together using 60/40, pressure tested at 120PSI and it hel
20:46 GuShh_ of course that's only half it's nominal pressure
20:46 GuShh_ err twice.
20:47 GuShh_ usually it works at 4BAR, tested at 8BAR, rated 10BAR in theory.
20:47 GuShh_ since it's the threaded portion that broke, I wonder if the stress of installing it won't damage it again
21:11 rue_house now that I'm temp without UPS, there will be silly power outages all the time
21:25 rue_house ooo new screen config, 1600x1200 :)
21:50 theBear i must've not had a tv for a long time.... apparently we now have 0 analog channels and 41! digital ones, tho i suspect several are doubled up
21:51 theBear i can't pay attention for long enough to scroll thru them all without a remote :)
21:51 theBear suppose i should do the old zap-out-every-poweroff-command-in-the-world with a pc-ir whatsit and when i get it to see something just bruteforce it :)
21:51 theBear it's some ridiculous noname brand, not even a known one like say, conia :)
21:54 theBear been running fine all morning... does something happen to hv/hf leads over time (standard silicone floppy insulation ccfl leads), like they breakdown ? either that or the osc/feedback has drifted, one of the transformers sounds a little grumpy, but that's not uncommon in a dirty cheap inverter circuit, but running the leads near groundplanes (metal chassis parts, foil etc) seems to have fixed it right up
21:54 theBear lotta leakage too, with either lead disconnected at the screen end (2 leads, 2 tubes, hidden 3rd join wire i suppose) and far from any chassis i was seeing maybe 85% brightness cycling during my diagnosing/testing
21:54 theBear nothing when disconnected at the psu tho
21:55 theBear sure they're not arcing or got a broken tube-end-join or anything, just seem to be very leaky in the leads, and i was lazy today, so i just left it like that for now :)
22:13 GuShh_ is theBear talking to himself again?
22:13 GuShh_ silicone leads will break off after some time if they are exposed to heat
22:14 GuShh_ that's the stuff used on the boilers I used to service, thick double silicone insulation, very similar to HV cables except it was for heat insulation mostly.
22:15 theBear nah, this is just light duty stuff, like you see well, in the back of lcd/ccfl screens
22:15 GuShh_ also rubbing against a sharp edge will make it slice clean off
22:15 GuShh_ yeah I know they're tiny by comparison but the same material!
22:15 theBear yeah, i know the sharp thing from my time in disco lighting
22:15 theBear it's the only wire that can get CLOSE to a 700-800C surface temp bulb :)
22:16 GuShh_ the spade connector insulators would often fail but the cables would remain intact
22:16 GuShh_ ....until they moved to moulded silicon insulators and that solved it, however I can't seem to source those anywhere
22:16 theBear and thinking about that, i suppose only a few of them were hi freq, and nothing like ccfl hi freq, but they never broke down... maybe the oscillator is just drifting, old resistor or leaky transformer or something, and it just needs to be close to gnds to keep things barely within specs for the protection circuit
22:17 GuShh_ I just made a 1/4 bsp adapter using some irrigation fittings and ingenuity (namely heat)
22:17 theBear and this isn't JUST silicone single conductors, they've got a seethru plastic sheeth around the outside too, loose, like err, the plastic they make those shitty transparent pencilcases and things from
22:17 GuShh_ surprisingly it holds air with no leaks and the threads are almost perfect, it's like an injection mould except low tech
22:17 GuShh_ not sure what plastic it is, the black fittings used on irrigation
22:17 theBear moulded silicone spade-insulators ? that's kinda fancy
22:18 theBear heh
22:18 GuShh_ nice stuff
22:18 theBear hehe
22:19 GuShh_ they're regular spade terminals with a silicone shroud, I tried heatshrink and while it looks neat, it falls apart after a few hours
22:19 GuShh_ http://ogrforum.ogaugerr.com/fileSendAction/fcType/0/fcOid/14804764762163291/filePointer/14804764768198064/fodoid/14804764768198060/imageType/LARGE/inlineImage/true/pRS1C-2266750w345.jpg
22:20 GuShh_ theBear: do you know what type of plastic they usually employ on those black fittings for gardening, irrigation, etc?
22:20 GuShh_ it doesn't say anywhere...
22:21 theBear umm, i should actually
22:21 GuShh_ I want to try some experiments now that I know it moulds so easily
22:21 theBear it's the same they use for no-tools high pressure air stuff
22:21 GuShh_ I press fitted it to a threaded adapter and the threads came out perfect
22:21 theBear i wanna say ptfe, but that doesn't feel right
22:21 GuShh_ (while it was very hot)
22:21 GuShh_ I don't know if I can melt PTFE
22:22 theBear that's a point, i never tried, but it does seem pretty tough
22:22 GuShh_ me neither
22:22 GuShh_ the only PTFE used on those boilers are on the caps as o-rings or some sort of bushing
22:23 GuShh_ of course I'm not using this on high temperature, just moderate air pressure to test for leaks
22:23 theBear hmm, websurfage for high pressure air stuff suggests "thermoplastic"/polyethelene
22:23 GuShh_ could've bought an adapter at the stores (I think it's 3/4 to 1/4) but who has the time, will and money to even care
22:24 GuShh_ also I challenge anyone to come up with an adapter in the 5 minutes it takes to make it from a random fitting vs going to the store, unless you live one block from the store in which case you'd win!
22:25 Shh_ would've used a lathe but he doesn't have a proper metal la
22:25 GuShh_ the things I'd do with a lathe! unlike most people who just buy one to gather dust in a shed... I'd actually USE IT!
22:26 GuShh_ theBear: maybe it's HDPE
22:26 GuShh_ one thing I wouldn't use with any sort of high pressure is PVC
22:27 Jak_o_Shadows PVC is fine for high pressue. As long as everything you care about is outside blast range, and you don't care about it breaking
22:27 GuShh_ that's like saying a hose made out of toilet paper is fine for your car's turbo as long as you don't care it bursting the moment you crank it
22:28 Jak_o_Shadows yep
22:28 GuShh_ perhaps you could reinforce PVC much like you'd reinforce concrete, but why waste the time and money
22:29 GuShh_ If you can afford it, copper!
22:29 GuShh_ I need to run "central air" in the garage but so far I've been using a couple extension hoses...
22:30 GuShh_ having a fitting on the outside would also be useful
22:31 GuShh_ when I researched the subject I noticed some people were using long vertical runs with purge valves on the bottom as a sort of water condenser / separator to unload the actual filters, it seems to work but I wouldn't think it's justifiable unless you use the compressor all the time.
22:32 Shh_ has yet to finish his automatic purge valve for the compressor, he couldn't find a cheap one that didn't
22:33 GuShh_ at least I purge the tank once or twice a week (partial purge to get rid of the liquids) --- a friend used to work on a bowling center and their tank was never purged in 20 years, it was one third full of oil and rusty water... surprisingly it's still holding, no punctures.
22:33 GuShh_ big 250L tank
22:35 theBear oh, were you still talking at me ? we was all split
22:35 GuShh_ theBear : mostly talking to myself
22:35 GuShh_ ranting about purge valves on air compressors and wanting to have "central air" at home (fittings on the garage and outside)
22:36 theBear yeah, it's amazing how much water builds up, at old-work i was the only one who ever considered maintenance on well, anything really, every week or 2 i'd do the tank, and there was always a lot of water, often pretty browney red,the stains are still in the carpark and i aint been there for around 2 years
22:36 GuShh_ haha
22:36 theBear i'd be interested to 'own' one of those water/oil filter thingers sometime, see just how well it works and how much it pulls out
22:36 GuShh_ I get a few drops out every time I partially purge it (manual valve, I got a solenoid for it but I need to build the timer circuit) I would imagine the humidity on the air plays a big role as well as the overall use of the unit
22:37 theBear i mean, it's not often a tank is so moist or oily that you notice blowing tiny electronics or using a nailgun, but airbrushes and things, i imagine a little oil makes a LOT of difference
22:37 GuShh_ I want one too, the dual ones with optional oiler and the water separator
22:37 GuShh_ ideal for painting
22:37 GuShh_ it does, the water and oil creates tiny bubbles in the finish
22:38 theBear mmm, oil-adder is good for nailgunning, specially things like those BIG twisty nails for hardwood decking or big fat 3"s for framing
22:38 GuShh_ heh not like I own any pneumatic tools
22:38 theBear mmm, i know what water and oil do to paint, just never used real airbrushes enough to see how much comes out
22:38 GuShh_ I want an impact wrench, those are very handy...
22:38 GuShh_ enough that you get a textured finish
22:38 GuShh_ speckled, as if you blew dust or fine sand on the fresh paint
22:39 GuShh_ except it's from within, ie. tiny trapped bubbles of goop!
22:39 theBear i only ever owned a little handle-airduster thinger, but over the years i've work-owned a few things for long periods, mostly nail and staple guns
22:39 Shh_ tries to think when was the last time he used a
22:39 GuShh_ oh when I built some "scaffolding" for the roof, using old wood pallets.
22:40 theBear at recent ex-work boss guy had one of those little stupid-hi-speed grinder things he used to clean off speaker frames for reconing... seemed to work very well
22:40 GuShh_ I'd like one but they seem to use a lot of air
22:40 GuShh_ the grinding tools in general
22:40 theBear air tools are kinda cool, fairly simplistic, very servicable, not expensive
22:40 GuShh_ I only have a tiny compressor, if I had a bigger external tank I could probably get away with big tools
22:41 GuShh_ 50L
22:41 GuShh_ I've toyed with the idea of repurposing a propane tank
22:41 GuShh_ the big ones.
22:41 theBear i'm bad at imagining liters in large numbers... how big is a beer keg ?
22:41 theBear i used to know that, i've really let myself go :)
22:41 GuShh_ hmm
22:41 GuShh_ there are 50 liters kegs, but are those the regular ones?
22:42 GuShh_ the stainless, big ones they use on pubs
22:42 theBear mmm, that could work... i've seen the small stubby bbq tanks with a couple fittings in them used as tyre-puffers, you know, for field-replacement of tubeless car/truck/whatever tyres, just to get that initial seal with a big PUFF, you put a kinda squashed-funnel on there, valve/fitting for in and out, off you go
22:43 GuShh_ the usual sizes on hobby grade compressors are 25L, 50L, 100L and then you've got the semi industrial and industrial stuff at 250L and over... with massive high/low multi cylinder belt driven beasts
22:43 GuShh_ Yeah pressure wise they're fine for 120PSI air
22:43 GuShh_ but I've heard a few things such as you can't get rid of the propane smell
22:43 Triffid_Hunter I think propane cylinder would work beautifully if you can get the fittings to behave.. fill it with water first then flush it thoroughly to avoid condensation
22:43 GuShh_ and then the dangers of improperly installing a purge valve (or failing to install one at all)
22:43 GuShh_ corrosion wise
22:44 GuShh_ my problem is, old tanks are in bad shape... the big ones that is.
22:44 theBear yeah, that's regular where i learned to drink :) so i'd say that 50l is more than enough for almost any kind of nailing you can do, framing going fast as the wind it keeps up so long as the low-refill on the controller valve isn't too low, if yer got a few people laying decking or something and are just going BANG BANG BANG constantly with BIG fat nails (lotta air) you get a couple every refill that don't quite go right in, but it's still very usable
22:44 theBear , and 'easy' for a single person to lift in/out of vehicles and get around so long as it got wheels
22:44 GuShh_ this house had two big ass propane tanks because it was built when no natural gas was available in the zone
22:45 GuShh_ ...they got stolen, so I don't have the option to repurpose those heh
22:45 GuShh_ someone drilled the bolt and took both cylinders
22:45 theBear mmmm, there's a bunch at grans place about as big as me .... they never had piped gas in the country there
22:45 GuShh_ yeah those ones.
22:45 GuShh_ stubby and tall (that's how much I know about gas stuff...)
22:45 GuShh_ not that you're stubby, but the tanks are.
22:46 GuShh_ it's a shame though since all the piping could've been repurposed and the tanks were already "indoors" and out of the way
22:47 theBear bit stubby, damned huge, WAY bigger than 'big' oxy-acetylene tanks
22:47 theBear the oxy/acet. ones tend to look like double length scuba tanks
22:48 GuShh_ yeah
22:48 GuShh_ I have a small oxy tank
22:48 theBear i'd guess roughly the same volume as me, just a little shorter and more consistant
22:48 GuShh_ it's expired, used it with air for fun while experimenting with a fridge compressor
22:48 GuShh_ very silent, I want to rebuild it this time permanently for airbrushing
22:48 GuShh_ it just needs a proper oil / water separator and a way to recirculate whatever oil comes out
22:49 theBear mmm, expired is a bit scary for gas, specially in rough situations like everyday welding or unsupervised under a bbq or outside a kitchen, but air ain't so scary, it's not like it'
22:49 GuShh_ free fridge compressor, can't argue with that. it just needs a "starter" unit
22:49 theBear s gonna EXPLODE and shatter shrapnel everywhere, it'll just start leaking
22:49 theBear starter unit ? what, a cap ?
22:49 GuShh_ they're rated for massive pressures, at least the oxygen tanks
22:49 GuShh_ so 120PSI is childs play for them
22:49 GuShh_ the starter relay that comes in a little box
22:50 GuShh_ magnetic driven "thermal" protection
22:50 theBear yeah, that's a point too, and as we both know, these 'little' compressors seldom pump over roughly 120
22:50 GuShh_ mine actually came set to 95-100 PSI
22:50 theBear interesting... i never played in fridges much, and my old easy-to-access aircon experience is pretty limited too
22:50 rue_house wow, the power out of the UPS is actaully better sine than the mains
22:50 GuShh_ I think the safety valve pops at 125 or 130, not sure. mine is the shitty red plastic type, I want to replace it with a brass one
22:51 GuShh_ theBear: I think you can get 300PSI easily with a fridge compressor
22:51 theBear most of the ones i seen the last 10 years or so have an adjustable limit on the output but the pump-cutoff is always set to around 110-130psi, never really looked if you can fiddle that
22:51 GuShh_ I just had no fittings or valve capable of over 80PSI (safely) so I didn't try to go over
22:51 theBear mmmm, someone was talking about fridge compressors modded for air compressors recently, probly in electronics
22:51 GuShh_ the dual ones with a 100L tank are an amazing option if you airbrush a lot
22:52 GuShh_ very silent.
22:52 GuShh_ there's just the oil issue
22:52 GuShh_ they spout a lot of oil.
22:52 GuShh_ and if you don't recirculate what comes out, you end up frying it
22:52 theBear i'm pretty comfortable with the standard 4 or 6 various clip-fitting standards up to 130 or so, not much higher tho, when they get old and wobbly popping off at 120 even with a no-leak-auto-valve-thinger in the pipe is pretty close to face-smashing
22:53 GuShh_ 120PSI pop even at 1/4" is scary.
22:53 GuShh_ I've got brown stains to prove that.
22:54 theBear hehe "are you at all worried about today ?" "i'm not wearing the brown undies for nothing mick !"
22:55 theBear grrr.... you may not be able to see it from there, but this means i'm going to have to go outside and find more cigarettes very soon :(
22:55 GuShh_ ...I had to replace the oil on my compressor a week ago, ended up using 30W40 motoroil because nobody here sells proper "air compressor oil" --- I came to the realization that it's the same stuff, even though they claim it's "non detergent" and thus doesn't keep the particles in suspension
22:55 GuShh_ I've yet to see foaming, which they also claim happens with regular motoroil
22:55 theBear still feeling ok today, only takes a minute to the corner store on the pushbike.... takes FOREVER with the stick
22:56 GuShh_ others claim ATF is better than motoroil if you can't find ND30W
22:56 theBear yeah, from what little i know most motor oil has some anti-foam/consistancy stuff added, if you think about it, an engine is pretty much the same as a compressor from the oil p.o.v.
22:56 GuShh_ that's how I think!
22:57 GuShh_ except for the part where the poop gets suspended in the oil vs falling to the bottom of the sump
22:57 GuShh_ motoroil is detergent because they use forced oil (pumped, filtered)
22:57 GuShh_ small air compressors only agitate the oil like any small 4 stroke engine
22:58 GuShh_ then again, I use regular motoroil on my 4 stroke mower....
22:58 GuShh_ so the other issue is "ashing"
22:58 theBear recently when i've been short of oil around the house i've just used some err, i dunno, 10-25 or some such power steering oil the last monkey left behind on the back porch... seems fine, little thin for the pusbhike shocks (in the back of my head i still tell myself the 15y.old no longer made rubber stanchion seals are fine <grin>) but the washing machine gearbox seems fine with it :) hint, if you see a strange plate bolted onto the bottom of your wa
22:58 theBear shing machine mech, turn it COMPLETELY upside down before you loosen it, cos it may well be a gearbox full of oil <grin>
22:58 GuShh_ I doubt that happens on air compressors since they don't run nearly as hot as an internal combustion engine (at least I think so)
22:59 theBear i wouldn't think so, tho the cheap small-heatsink modern ones do run pretty darned hot if they don't get long breaks
22:59 GuShh_ then again the old oil came out black heh
22:59 theBear i'd think hot enough to get the thinner value on range-numbered motor oil at least
23:00 theBear heh, after 15 years you shoulda seen the shit that came outta my pushbike shocks !
23:00 GuShh_ if I can find some "ND" type motoroil I'll swap it, until then I'll keep using what I have
23:00 GuShh_ was it tar like? heh
23:00 theBear there was no oil left, just mud and pulverised unidentifiable stuff :)
23:00 GuShh_ lol
23:01 GuShh_ speaking of seals I think my small chainsaw has bad seals on the crankshaft... fun...
23:01 theBear but even now, tho i gotta put a rag around them so they don't leak on the floor, they hold air better than they ever have
23:01 GuShh_ those seals must be pretty generic though
23:01 GuShh_ on the shocks
23:01 theBear mmm, never fun getting RIGHT into the depths of a chainsaw, easy enough to peek in the cylinder, maybe take the top off, but you gotta take them to their component pieces to get to the crank
23:02 theBear probably, problem is that as the years go on alloys have gotten better and lighter, so there's nothing NEARLY this small outside of noname chinese k-mart shocks
23:02 GuShh_ hmm
23:02 GuShh_ I never serviced the shocks on mine
23:02 GuShh_ and you're right, they are very light now adays compared to what I have
23:02 theBear i might random-order if i see some the right size one day, but you can get MUCH better tech shocks for a couple hundred bucks new now
23:02 GuShh_ which uses a steel frame...
23:03 GuShh_ pfft invest the money on a 50cc engine!
23:03 Shh_ g
23:03 GuShh_ I think you don't need a license or insurance here for that kind of vehicle
23:03 theBear mine is an ally frame, '94, BIG oversized silly tubing and fat square chainstays and stuff, 6000 or 7000 series alloy, but they had only just got the hang of that back then, shocks were still all heavy cast and steel stanchions
23:04 GuShh_ the rear shock on mine is stuck
23:04 GuShh_ well the adjusting "screw" is
23:04 theBear i been thinking about it... they're on the verge of the law here, but i'm discrete... kinda like the idea of getting the smallest bmx frame i can fit one in and making a joke-chopper, not even have pedals, just a tiny motorbike
23:04 GuShh_ it has a spring inside and it got caught with the threads
23:04 theBear :(
23:05 GuShh_ with a proper muffler they aren't as annoying as one would think
23:05 GuShh_ you still look like a tool but it's a cheap way of moving around
23:05 GuShh_ and not having to spend money on insurance companies
23:05 GuShh_ hell you can convert them to run on propane I bet
23:06 GuShh_ I know those tiny 2 strokes will run on nitro(methane) if you play with the carb just a bit
23:06 theBear yeah, i've spent time on a couple, ooh, i gotta find the pic of the one i ride when i'm on holidays where i used to live... it's ridiculous !
23:06 GuShh_ I've got highways all around, it would be a dangerous and very silly idea to drive around one of those :p
23:07 GuShh_ borderline illegal as well
23:07 theBear yeah, they're quite happy with 5 or 10% after a runin with minimal if any tuning
23:07 theBear but wait for this pic
23:07 GuShh_ I'd totally convert an old motorcycle to a diesel engine if I had the parts though
23:08 GuShh_ something like a lister
23:08 theBear http://i.imgur.com/wWAkosV.jpeg there 'tis !
23:08 GuShh_ and run it off whatever oil is left from the kitchen!
23:08 GuShh_ that's not ridiculous that's awesome compared to the shit they sell over here
23:08 GuShh_ look at the air filter! looks like a K&N
23:09 theBear ridiculous backwards headstem to make it handle like a drag-bike (VERY poorly) ridiculously heavy giant wheels and frame, 80cc engine, fancy carb, custom welded muffler, nitro fogger tanks, suicide shift (hub gears) on the side you can't see, ridiculously far back seat :)
23:09 theBear it's just golden !
23:09 GuShh_ fancy
23:09 theBear only me and my buddy who built it can ride the thing, but damn does it feel awesome crusing down the road and reaching down for the suicide shift on a 'moped' :)
23:09 GuShh_ the conversion kits are not geared I think it's just a centrifugal clutch
23:10 GuShh_ so they're not very nice...
23:10 theBear i've seen a fair few of the generic rebranded by everyone 50 and 80cc kits, cable pull clutch and no gears
23:10 GuShh_ I wonder if anything over 50cc would be allowed, legally speaking
23:10 theBear this one has some fancy freewheel between the pedals so you don't need a 2nd chain and can take advantage of the hub gearing
23:11 GuShh_ but even at 80cc you probably get a big MPG
23:11 theBear here in various states it shifts around, and that's also why they call them 49cc <grin> ... sometimes it's x hundred watt electric equivalent, other times it's under 50cc = not motor vehicle, other states it's not yet legislated... generally you get away with it so long as you aren't an idiot and wear a helmet
23:12 GuShh_ last bullshit product I've seen, related to motorcycle and "speed" mods.... an electric turbo for regular carburetors... what a wanky idea
23:12 GuShh_ takes around 10A from the poor tiny starter battery as well
23:13 theBear also it makes a lot of difference if you get the cheapest rebranded kit around and assemble/mount it poorly, or if you put/make real gaskets and generally 'rebuild' the engine at least once, a few companies charge a few hundred bucks extra for basically rounding off the cast marks and gentling the edges of the ports and things, but pfft
23:13 GuShh_ they're sold for 4 stroke bikes and I fail to realize how exactly you'd set up a regular carb to work with it
23:13 theBear electric turbo ? like err, a fridge pump ?
23:13 GuShh_ since the air mixture would get too lean and you would essentially be running off fumes when you turn that thing on
23:13 GuShh_ it's like a CPU cooler but heavy duty that clamps to the air intake of the carb
23:14 GuShh_ probably meant for retards with too much money in their pocket
23:14 theBear lol
23:14 GuShh_ and then of course conversion kits for engines.... take your 150cc to 180cc!
23:15 GuShh_ next thing you know you've spent more modding that bike than it would've cost you to buy a 250cc one
23:15 GuShh_ also not sure on the legal aspects of that
23:15 Jak_o_Shadows Triffid_Hunter: I should put flyback diodes on the hip 4082 circuit yeah?
23:16 theBear i wonder IF you can get enough electricity to move/compress that much air, whether you actually gain anything or just lower your overall efficiency :) that's the cool thing about turbos (conceptually, supers are still what you want sticking out your bonnet if you got a 'silly car',) they take 'used/wasted' energy from the exhaust and make it generate a lot more 'for free'
23:16 GuShh_ theBear: http://articulo.mercadolibre.com.ar/MLA-455816215-kit-turbo-motos-12-v-_JM
23:16 GuShh_ it's all bullshit
23:16 GuShh_ plus the poor magneto wouldn't be able to keep up
23:16 GuShh_ and you'd just end up with a flat battery and no way to start the bike unless you push it (some bikes don't even have a starting pedal)
23:17 theBear yeah, quite a few these days
23:18 Triffid_Hunter Jak_o_Shadows: I didn't on my ESC. I'm relying on the mosfet body diodes for that
23:18 theBear heh, i had to look at that HARD, looks like a headlight kit :)
23:18 Jak_o_Shadows Doesn't hurt though?
23:18 Triffid_Hunter Jak_o_Shadows: it's good practice to add flyback diodes, but high current shottkys push the pcb size and cost up
23:18 Jak_o_Shadows haha, you talk like i'm making a pcb
23:18 theBear hehe
23:19 Jak_o_Shadows I mean, i'd love to, but time budget and experience restricts that
23:19 theBear erg, such a successful morning, played with a tablet and got a tv/big screen working again finally, almost tamed that STUPID old intel bios to boot in the silly way i want it to, gotta stop celebrating and have a shower and eat something i suppose
23:20 theBear speaking of budget, i been thinking of pcbs a lot again recently, even know where my old photographic pcb kit is (back in the days when you sensitized the boards by hand :) but suspect i left my ferric behind when i moved states
23:20 GuShh_ hmm
23:20 theBear also don't seem to have my pyrex 'developing trays' anymore
23:21 Shh_ eyes a wood l
23:21 theBear of course i'm no longer a kid, and know that only fools don't use a vertical tank to save evaporation and allow bubbles and stuff
23:21 GuShh_ lost my tank on the move
23:21 GuShh_ it was a small fish tank...
23:22 GuShh_ left behind, couldn't cope with all the shit on my own
23:22 GuShh_ :(
23:22 Jak_o_Shadows How well does the silicone joints and stuff on fish tanks cope with the etching soln?
23:22 theBear i never had one, it was a miracle i did as well i did back then... almost zero chemical experience, zero photographic experience, no buglights or 'real' darkrooms, just pulled blinds and bedrooms, rule of thumb sunlight exposures etc etc
23:23 theBear i can't remember if silicone is the right stuff to use, rif knows, but apparently something quite common is VERY durable for that kinda thing
23:23 GuShh_ hey I used what I had and it worked just fine :p
23:24 GuShh_ I haven't been much into electronics lately, but that auto purge valve for the air compressor seems like a nice project
23:24 GuShh_ it's mostly about the enclosure and other hardware that I haven't built it yet though
23:24 theBear auto ? what would trigger it ?
23:24 GuShh_ time
23:24 GuShh_ or cycles
23:24 theBear ahh, that makes sense
23:24 GuShh_ auto purge for X seconds after Y run cycles
23:25 theBear i instantly imagine it driving you mental when you aren't expecting it tho
23:25 GuShh_ that's why I thought to add a beeper
23:25 GuShh_ because it would scare the hell out of me otherwise
23:25 theBear i suppose if you just do a little bit at the end of a fill cycle, regularly, you wouldn't notice
23:25 theBear being auto it could be a tiny purge fairly regularly vs a big manual one when you think of it/get a chance
23:25 GuShh_ yeah well in that case you'd be purging off whatever was gathered from the previous cycle, but that works too
23:25 GuShh_ right, they do sell these things
23:26 GuShh_ I just don't have money to spend on that
23:26 GuShh_ nor would I buy one
23:26 theBear you'd preferably want a tank with a sloped bottom tho, even a tubular tank on 'flat' ground needs a good wiggle to get the last bits out
23:26 GuShh_ yeah, been fooling around with the leveling of the tank
23:26 GuShh_ it's not easy
23:26 GuShh_ when I purge it manually I have to lift the tank up to get most of it out
23:27 theBear suppose if you went for a slightly elevated-one-end tubular tank, and got the valve on the bottom 'corner'
23:27 theBear yeah, i used to let the bulk of it go on its own then kinda use the tank like an inside-out-level-bubble with my ears to get the last bits to the valve
23:27 GuShh_ valve tap is already there, I just need to empty the tank and replace the thumb screw with a solenoid valve (with manual adjustable flow too)
23:28 GuShh_ it's all brass and the water is quite oily I think it would last a long time
23:28 GuShh_ normally closed valve, 230VAC coil
23:29 GuShh_ power consumption is irrelevant since it would only operate for a few seconds
23:29 theBear erg ok... i gonna do some domestic kinda stuff... bbl
23:29 GuShh_ I think an auto purge after each cycle would be the best bet instead of a "programmed" or "counted" purge
23:29 GuShh_ heh it's 1AM here, my domestic kinda stuff involves sleeping :p
23:30 GuShh_ anyway automation is the way to go, one less thing to worry about.