I would be cautious of putting a conductive tube around the primary. It would look like an aditional shorting turn to the magetic fields. If you want to shield, a ferrite shield that is not electricaly conductive is much better. A steel tub would be a bad idea. This why transformers are made up from laminated steel or ferrite so as to avoid eddy currents and the associated losses and heating.by aka47 - General
I guess that is one route. Personally I prefer a closer shave with Occams Razor (Raisor ??). If I needed to know the temp of the primary circuit so as to null it out I would measure it with a thermistor. With suitable filtering. The time constant of thermistors is of the order of magnitude of seconds. So filtering this should be straight forward. Maybe a Pi filter. There again if I wanted tooby aka47 - General
Like wow, gobsmacked. That is a solid lump of work there. I am truly impressed. You must be getting on for a couple of papers worth of work there if not a thesis. What frequency to model for is an interesting question. My gut feel for this is that 100Khz is plenty. For example the LT3573 can be set to switch at between 40 and 1000 Khz. 40Khz is a sensible minimum as it is safely beyond hearinby aka47 - General
The funny thing is that custom DNA strands are currently easily automatically synthesized. The fun bit is putting a cell around it and kicking it into action. If you can get that bit right the next bit is bio devices that will self fabricate. (Bacteria and Yeasts are good models to start with) DNA is routinely sequenced up as primers etc in bio labs and the technology is about ripe for a low cby aka47 - Tissue Engineering
Remember Reprap was crazy stuff less than 4 years ago. The majority of the populace still think it is crazy stuff. If no one bothered with crazy stuff there would be no Reprap. Something worth considering. You of course are welcome to ignore it and move on. "This is not the crazy stuff you are looking for" (said in Obi Wan style)by aka47 - Tissue Engineering
Been kicking around some ideas for power heater control using a variant of Burst firing. I got to thinking that it is fine to DC supply everything but probably most of us are using large ish power supplys fed from AC mains to rung heating anciliarys (Beds etc) and extruders. Sometimes too we want to experiment with say hot air flow or other stuff. Loading up our existing DC supply to much is a bby aka47 - Firmware - experimental, borrowed, and future
If you have a test meter and or good eyesight it might be worth checking out the connections on the board for dry joints etc. Pins on chips are usually good or bad, very rarely intermittent. Intermittent working stuff is usually a bad socket contact or dry solder joint. If you cant see any dry joints re flow all the joints relating to that pin anyway using a fine soldering iron. It may just worby aka47 - Firmware - experimental, borrowed, and future
>> Might be worth stating explicitly what the >> prerequisites are for a successful build/load. >> Sorry if I have missed this somewhere. > >I'll put it right here then- >build requires: >gnu make >binutils, gcc and associated tools built for avr target (avr-gcc) >avr-libc >program requires: >avrdude >something that avrdude knows how to talk to (bootloby aka47 - Firmware - experimental, borrowed, and future
Guys Dumb question/s time. To program the compiled hex to a given microcontroler, does it need to have the Arduino bootloader in place ?? I have had a rummage through the makefile etc and it looks like this is the case. Just wanted to check in case I was missing something or other. Failed miserably with "make program" using an Atmel AVRISP... Might be worth stating explicitly what the prereqby aka47 - Firmware - experimental, borrowed, and future
Guys I think you have probably done the opto end stop thing to death. I agree that the best way is to add a bit of signal processing at the end stop, end (Buffer, emitter follower or what ever) and drive the line harder. It can also be filtered (Pi filter) with a couple of small value caps and an inductor. However...... Cheapest and simplest route is to throw out the opto end stops and useby aka47 - Firmware - experimental, borrowed, and future
Certainly moving your temp sensor close to or on your heater is a very good move.by aka47 - Firmware - experimental, borrowed, and future
To be honest what I am suggesting depends a little on what you want to do with it. I am talking about two different scenarios at the same time and this will probably be confusing. Sorry. In both cases I am suggesting using a fly-back SMPSU circuit and controller (to be decided, choose one you fancy) as the way to run the induction heater. With the micro-controller telling it what temperature toby aka47 - General
I will be honest I am starting to get towards the limits of my grip on the subject so could be a little out. My understanding is that with Current mode Flyback converters you are not actually getting feedback from the secondary. You are measuring how much is left in the primary at a given point in time such that you can infer how the conditions in the secondary are impeding energy transfer fromby aka47 - General
Given that the Gcode spec on the reprap wiki has error correction and re-transmit (Line number and checksum). It is a little dificult to see how to do non buffered line at a time reliably if the comms becomes a bit noisy/shaky. When I have got a machine together and rehashed my touch probe work I think I would like to contribute some code for probing. the original probe/pen holder stuff is a litby aka47 - Firmware - experimental, borrowed, and future
Wow your pushing my envelope with the math a little, but great well done. I though you had somehow measured it, clever.by aka47 - General
Excellent. can we get some figure for mild steel it should be more. mild steel or bolt steel has the added advantage of concentrating the magnetic field. aka47by aka47 - General
Triffid _Hunter sir I really could'nt agree more. There is a very real case for keeping the Host/Human Interaction separate from the Machine control. To do other wise is to invite problems due to the fact that the two areas have conflicting priorities. A serial interconnect ( whether from Ethernet or USB ) is a very good common denominator and you have the ability to throttle the input stream tby aka47 - Firmware - experimental, borrowed, and future
Best way to loose the serial port stuff is to go Ethernet but you will then loose everyone who has not got and doesn't need networking. The benefit to serial is it is a lowest common denominator. The really best route is to add other methods of communication in addition. Then you use the one you want.by aka47 - Firmware - experimental, borrowed, and future
Yes I think you have a good point there, Loading method needs to be taken into account. Recently I have been looking at the xmega range and they look quite promising. They seem to have a funny event driven element to their hardware that can optionaly be used to create a certain amount of automated event driven IO. Not entirely sure i understand it completely but for machine control applicationsby aka47 - Controllers
A quirk of PID is that the entire thing is heavily influenced by how fast you PID versus what the time constants of your heater circuit and feedback are. I found this building a Duck Egg incubator that I wanted to be fairly accurately controled. It was DC control so the loop versus supply frequency was'nt an issue. If the loop is running too fast then it over compensates followed by a correctiby aka47 - Firmware - experimental, borrowed, and future
I think a great use for a slave processor is as a printer controlr and human interface device. It could be interposed serialy between the host computer (or none at all) and the printer. Providing SD card, keypad and display as well as a largish buffer. These are functions that are realy useful but get in the way of speedy control of the mechanism so ar ripe for being algorithmicaly re distributby aka47 - Firmware - experimental, borrowed, and future
A little more on topic. The atmega1284 is now available (I got a couple of them) in 40pin DIL format so is a direct drop in for the 644p DIL but with more memory. On having a reprap do its own circuitry I had a sudden blast from the past. The first microcontroler boards i made and programmed in machine hex machine code were wire wrapped. Wire Wrapping is something that a Cartesian Bot could bby aka47 - Controllers
I think the easiest motor to design for printing (Though not to drive) is a Brushless DC motor or BLDC.by aka47 - Mechanics
I guess of course the current sensing method is only really necessary for those going with a glass nozzle design. Otherwise:- Where I could get a thermistor or some such in contact with the end/side of the nozzle I would go with that. Assuming that there is noise to pickup. As the frequency is high, known and fixed it is doable to filter it out of the thermistor leads with something like a Piby aka47 - General
A better example of the technology (again not limited to) is perhaps the LT3573 This looks at the primary waveform to work out what the voltage is in the secondary. Maybe having a single shorting turn in the secondary will mess with this, maybr not. I guess we are a little off the "conventional" map here. Some experimentation is needed. Essentialy the ouput turn (Nozzle or heater insert) isby aka47 - General
maybe something like (but certainly not limited to) a LT1076by aka47 - General
Guys I have been musing on this a little and agree that perhaps the easiest way to the electronics is to re-purpose a dedicated switch mode voltage regualtor IC. Current Mode Flyback voltage regulators commonly use current sensing as a way to sense how much regulation they need to apply and are completely insulated from the secondary. (Flyback converters use a transformer with isolated primaryby aka47 - General
Guys I am quickly getting to the point where I need to start with putting some working firmware onto a huxley I am building and fancy trying your code for size. A quick couple of questions. How are you doing for pin numbers on devices when doing full 5d ?? (I know some of you are keen to stay with the 328) Has anyone implemented your firmware on a 644 or 1284 40 pin DIL ?? Where is your curby aka47 - Firmware - experimental, borrowed, and future
Umm I was'nt suggesting casting the nichrome into the glass rod. I was suggesting fusing a spiral (Glass filament) onto the glass tube with some anchor points that you could wind uninsulated nichrome onto after it had cooled. Then secure the nichrome and wire take offs with the anchor points you have made from glass. Winding insulated nichrome onto the glass tube just in case it shorts is compoby aka47 - General
Hmm looks like a job for scad and a parametric design. So that it can be scaled to suit differing shaft and bolt sizes by just changing a small number of parameters. Are'nt smart parts great.by aka47 - Polar Machines, SCARA, Robot Arms