Quotedc42 If your first peak is at 6.4mm transducer face height and the second one at 11mm, then your half-wavelength is 4.6mm, and you should get another, larger peak at about 1.8mm face height if your transducer was lower. As this is such a low value, I suspect that your maxima correspond to my minima, and vice versa. This may mean that your oscillator is operating at the parallel resonant freqby Radian - Ormerod
Ray, I for one am finding parameter storage in non-volatile memory a huge help as it saves the faff of writing parameters into files on the SD card while tinkering with the hardware - there may be other advantages. Must remember to comment them out in the files though.by Radian - Ormerod
Ah, thanks, looks very similar. Of course it doesn't look as elegant as blue!by Radian - Ormerod
I want to order some PLA in the same colour as the RS Ormorod but I'm not sure if it's red or orange. I mean, to my eyes, it looks somewhere between the two. Can anyone point me in the right direction (hopefully not towards RS and their high-priced filament). TIA.by Radian - Ormerod
Thanks for that. So far, so good - the raw z-probe readings are noticeably more steady using 057r-dc42 Actually with the 12V Supply switched off, using USB supply only, the readings from my Ultrasound probe are either rock steady or dither by just one count. With the 12V on and the 5V switching reg. running, the dither is still only 3 counts. I wondered if vibration from the fan might be addingby Radian - Ormerod
I was about to order some from the Ebay seller linked at the top of this thread but I want to print matching parts for my RS Ormorod - do we know if the red matches, or is it orange?by Radian - Ormerod
OK thanks dc42. I forgot to check your blog. I think I might be seeing a different response from the fixed frequency driver you're using (and I used before I settled on the resonant drive circuit). I quickly knocked out a python program to extract probe readings vs. height and pasted the output into a spreadsheet: That's the result of 3 runs at the same temperature. The face of the Ultrasoundby Radian - Ormerod
Quotedc42 3. Added additional optional Z probe parameters: calibration temperature, and temperature coefficient of height. Example: G31 Z0.8 P600 T60 C0.0076. If you do not specify a T value, then the current bed temperature will be assumed unless the G31 command is being processed from a file. Hi dc42, can you explain a little bit more about the temp.coefficient - i.e. the procedure required toby Radian - Ormerod
Hi dc42 - I've been using firmware version 0.57r-dc42 and can happily report that your modified Z homing sequence works well with the two-transistor Ultrasound circuit posted above. However, this is with the proviso that Homing is initiated when the nozzle is no more than 2mm above the bed. If the nozzle is any higher, homing always ends with the nozzle much higher than where it started from. Soby Radian - Ormerod
From your topic Re: Anyone interested in a modulated IR sensor + fan control + illumination board? Quotedc42 One snag is that there has been a run on 10mm 40kHz ultrasonic transducers since I built the prototype, and neither Farnell nor RS has any in stock. This may delay the Kit 5s till sometime in April, unless I add £3 to the price and source more expensive ones from Mouser, or ship the Kit 5sby Radian - Ormerod
Ormorod unused for 24hr+ Ambient on table 19 (IR non-contact thermometer) Head 18.9/19.6 Bed 20.3/20.4by Radian - Ormerod
Excellent! Scored panels or milled? I don't know if you've got a fancy shape for it or not.by Radian - Ormerod
So (in the absence of a true current sense) I get how under-voltage might be used as a proxy for current overload, but I wonder what conditions might cause over-voltage? Obviously failure of some other part of the PSU could be caught - but if it can maintain regulation (keeping under the maximum trip points) with zero load current then dummy loads seem pointless. Your tests show that there's no pby Radian - Ormerod
I'm sure it's all good. I just wondered if the 3.3V control circuit was part of the WT7520 or if it was independent - as I'd suspected from my own external load tests. Looking at a number of different schematics, I got the impression the 3.3V was considered more critical hence had it's own closed-loop regulation circuity. In the past I've used cheap ATX supplies without any concern over minimum lby Radian - Ormerod
So that was what was upsetting Octo! What I don't get is why it would unscrew - surely the net number of left/right moves cancel over any length of time? There must be some kind ratcheting action making a net twist in one direction.by Radian - Ormerod
Quotebobtidey Here are some load tests. I didn't bother too much with 3.3V loading. I checked it was 3.3V due to the local sense. The previous scheme and the modded one makes no load or usage of the 3.3V supply. Sure, nothing actually makes use of the 3.3V rail from the ATX PSU but switch-mode power supplies in general have several protection schemes and one of them is sensing minimum load and sby Radian - Ormerod
Hi Erik, glad to see Octo still has his jobby Radian - Ormerod
Hi bobtidy, I've all but given up on trying to engineer a "safe" external mod people could do to their supplies - so "solutions for the experienced hacker only" seem to be the last resort (short of laying out a modest amount of money for a more suitable PSU). You mentioned that you connected the 3.3V sense wire direct to the 3.3V O/P inside the supply - without any dummy load. This implies that tby Radian - Ormerod
Flatness of +/-2mm probably reflects the realities of any processed sheet material. I guess that only laser cut sheet stock would have a chance of bettering this kind of figure - which is probably guillotined. Given that this kind of cutting I'd certainly expect to be able to correct this by a factor of two or more with careful measurement and manipulation. But I agree that the surface might notby Radian - Ormerod
Hi Ray, I'm pretty certain this is a pukka laminated PCB - that is a 35um layer of copper, a (very thin) layer of fiberglass bonded onto 3mm Aluminium. I say this because the photos show it free of vias and through-holes for connectors etc. These are not possible with this kind of composite. The net result gives a huge thermal conduction path from the copper tracks to the metal. Warm-up time andby Radian - Ormerod
I just had what I thought was a good idea so I Googled it to see if it had already been done and found the exact thing: Quote Heatbed with 3mm Aluminum Core. Print directly on the heatbed, no need for glass plate. It's a much lighter solution than PCB heatbed + glass, which makes it better for faster prints. The great thing I see in this apart from the weight saving is the fact that the PCBby Radian - Ormerod
Yes, I was thinking only of having a low impedance path between the two points where 0V comes into the board. The 0V return for the high-current areas can remain pretty much as they are - independently branching away either side of the ATX terminal end.by Radian - Ormerod
I don't know what the definition of a Colpitts oscillator would be other than the use of a 180deg. phase shift amplifier and capacitive divider to shift another 180deg. to get things oscillating. Out of the two topologies I can only get the one I drew out above to work reliably... so far.by Radian - Ormerod
Ah, a very good wish-list. It looks like Item 4 relates to 12V decoupling, 7 is the regulator layout. Do you think there's any reason not to create a continuous ground plane on one layer that carries 0V between the USB and the ATX terminals? Inductance in the present narrow track allows the 5V/3.3V rails to be pushed around by currents in the large ground loop formed by the Printer & PC eartby Radian - Ormerod
Quotedc42 Radian, did you attempt to measure the change in oscillation frequency as the probe moves towards the bed? It occurred to me that this may be another way of height detection. I was thinking of trying a one-transistor Colpitts oscillator (operating at the parallel resonant frequency of the transducer, rather than the series resonance that we are both using at present) and then frequency-by Radian - Ormerod
Looking at the PCB design in KiCad it seems to me as though the layout of the A4403 5V regulator could have been better organised. The first thing I noticed was that there is no ground plane to speak of, instead 0V (highlighted blue) runs from POWER_IN as a track which goes point-to-point to the low end of the power components - while the datasheet recommends all these being Star connected. The sby Radian - Ormerod
Out of curiosity what do we think about using plywood instead of MDF for the bed? 4mm thick ply is pretty rigid but can be laser cut using hobby gear.by Radian - Ormerod
Quotedc42 How temperature-stable is the reading you get from it? Unfortunately I haven't had the time to built it on to a circuit board yet - it's still on the breadboard! I was just reading your new firmware topic - the Ultrasound options sound good, can't wait to try them out. But can you clarify for me what you mean about the threshold? Do you mean that the threshold value set by G31 shouldby Radian - Ormerod
I set up a rig to see if the resonant frequency varies with temperature and it certainly does appear to. Firstly, here's the complete circuit I made to drive the ultrasonic transducer: This oscillator circuit tracks the resonant frequency, producing around 8V pk. across the transducer. Zener D2 subtracts a constant from the peak to get within the A/D range. D3, R3, C3 hold the peak for samplinby Radian - Ormerod
Interesting, my pesky +ve homing offset was proportional to temperate as well. I'm currently working with a series resonant oscillator circuit driving the transducer - my thinking being that forcing it to operate at a fixed frequency when it's resonant frequency varies so much with temperature and range doesn't make too much sense. Once it's free to resonate at whatever frequency environmental cby Radian - Ormerod