Hello, indeed I have. Two chips gone (oops), I have 10, I'm sure I'll learn before I get to the last one :)
It amazed me that I managed to hand solder with hot air flow and soldering liquid paste a QFN40 first time with no issues, the LFCSP_LQ is obviously a different story. I tried to put less solder on the big center pad and all pins seem to be touching well, perhaps I burnt it but I was careful with the heating profile on the way up to the peak as well as down and how many seconds I spent on each phase. But hey! Who doesn't like a good challenge on it after a long day at work! I'll get there. Il giorno giovedì 10 settembre 2020 alle 00:50:22 UTC+1 gregebert ha scritto: > Have you tried using solder paste and hot-air reflow ? > > On Wednesday, September 9, 2020 at 3:07:35 PM UTC-7 flata...@gmail.com > wrote: > >> David and all, >> >> Just a quick update. I finally had some time to remove all cables and to >> solder everything directly, with the nixies being on sockets and I'm >> pleased to report that it all works great! >> >> Re: accelerometer ADXL335. I cannot get to solder that chip properly, >> quite tricky even under the microscope. I'll start again but I'm not too >> concerned about it, maybe I'll replace it with a chip in a different >> package, I find the LFCSP_LQ too tricky to hand solder even when following >> the recommended soldering profile. >> >> Re: HV 1308B - Turns out that the PCB layout that I posted here - while >> not ideal - works ok (ok-ish?) or at least it's not a disaster. >> >> I've added some tiny LEDs along the anode lines and they work great but >> they want a 1k resistor in series otherwise the tubes glow a bit blue, so I >> need to work around that. >> >> Next I'll look to add a photodiode to control brightness through PWM I >> suppose, the intention being to save power more than to dim the tubes. But >> I have some PIC assembly to chew first for PWM and perhaps I'll add touch >> buttons too... >> >> Nothing new for this group, but a whole new world for me. Feeling like >> I've been missing out! >> >> Thanks again for the suggestions given, >> >> Max >> Il giorno lunedì 31 agosto 2020 alle 20:11:55 UTC+1 Max DN ha scritto: >> >>> Now this is an honour! David Forbes himself! I'm a big fan. >>> >>> David, thanks for taking the time to reply in detail. I have been >>> studying your circuit for 2-3 months now (I know, for most people here it >>> may take a day or so, but my knowledge of electronics is very basic however >>> it's always been a passion of mine). My day job is in a totally different >>> field (banking) and since Covid lockdown started in the UK I have dedicated >>> some of my spare time to this project, just as a way to switch off, so to >>> speak :-) >>> >>> My wife insists I should just buy your watch but I like a good challenge >>> (more so I'd like to try to make a HVPS at least as efficient as the >>> Kopriso but that's some time away for my basic knowledge). I may still get >>> your Cathode Corner watch as a courtesy for sharing your entire firmware >>> and schematics. Beside, I like it as well and perhaps start from there and >>> try to update the software to add functionalities (such as date etc). I'd >>> also like to improve the efficiency of the high voltage circuit and have >>> worked on 2-3 projects in parallel, but I'm leaving those in standby for >>> now given my limited spare time. >>> >>> I do think my issues are the amount of cables currently running to the >>> Nixies as well as poor layout. And perhaps many more. In fact, I'm still >>> surprised that it works at all, although not perfect (the accelerometer is >>> not working at all or not working well, I'll look into that later, probably >>> due to poor manual soldering skills there). >>> >>> I have noticed that if I even try to just measure the voltage on the >>> feedback pin (I only get 1.17V or so) the brightness of the Nixies changes. >>> >>> The multiplexing doesn't work well with my current set up and you can >>> clearly tell it's there. I have taken a video if you are curious at all. >>> I'm loving this project and would like to keep the watch size of >>> 38mmx38mmx16.5mm which I think is achievable. >>> >>> Needless to say, David, your PC board design is compact and neat, my >>> first mistake was to have the feedback line running across the entire board >>> as well as the switching pin so far from the transformer and with its >>> copper wire running under the 1308B! Oops. >>> >>> Last, it's a puzzle for me that a (random) 2.2k resistor in series with >>> the VCLAMP line seems to improve stability. And works better with 3.2k. >>> It's probably affecting the resistive divider somehow. >>> >>> I think you are spot on with all of your suggestions (of course). I'll >>> focus on the feedback line for now and perhaps just start from scratch soon >>> by redesigning the high voltage layout. >>> >>> Thanks so much again. >>> >>> Massimo >>> Il giorno lunedì 31 agosto 2020 alle 19:13:26 UTC+1 nixiebunny ha >>> scritto: >>> >>>> Massimo, >>>> >>>> Hi. I see that you are trying to make the Cathode Corner Nixie watch >>>> circuit work, using your own circuit board design. it's not an easy >>>> circuit to build, because the design was optimized for size and >>>> efficiency, given the parts I had available. >>>> >>>> The power supply is designed to make 180V with no load. It is designed >>>> to make about 10mA of current with one Nixie tube lit, where the Nixie >>>> tube regulates the voltage to about 150V. There is a third voltage >>>> level that is selected by the TiltP signal, which reduces the HV to >>>> about 90V by changing the feedback divider current, through that 33K >>>> resistor. This is done to provide blanking for the tubes while the >>>> power supply is active, which makes the multiplexing cleaner. >>>> >>>> You can see that all of these parts interact, and the feedback >>>> resistor values were tuned after building a few watches, to get the >>>> display to look the best. I wouldn't have made it this way if I was >>>> only building one watch! >>>> >>>> The clamp voltage is not critical, since the clamp Zener diode is only >>>> conducting when high voltage is on yet no tube cathode is enabled. >>>> >>>> The circuit board layout is critical. I do not think that it will work >>>> properly if you have any length of cable on the Nixie tubes. This is >>>> because the capacitance of that cable, combined with the high votlage >>>> switching of mutliplexing, will generate noise and affect the timing >>>> of the cathode turn-on and turn-off. >>>> >>>> Here's a picture of the PC board design for the round watch power >>>> supply. You can see that I made all the high current 3V power and >>>> ground traces very short and wide, to prevent problems with the >>>> switching currents radiating into the feedback circuit. In fact, my >>>> first prototype PC board had the feedback line running across the >>>> power supply, and it failed, so I had to add a wire to move that >>>> sensitive line away from the noisy switching circuit. >>>> >>>> I hope that this description helps you to understand where to focus >>>> your attentions. >>>> >>>> >>>> On 8/31/20, Massimo Di Noi <flata...@gmail.com> wrote: >>>> > Hi all, >>>> > >>>> > I'm been following this group for a while and finally decided to go >>>> back to >>>> > >>>> > a hoppy that I had 15-20yrs ago or so, to brush up my old knowledge >>>> and to >>>> > build my personal nixie watch starting from what David at Cathode >>>> Corner >>>> > kindly shared, but looking to improve its efficiency with new chips >>>> and to >>>> > add functionalities similarly to Kopriso watch or else. I like the >>>> > capacitive buttons etc. >>>> > >>>> >>> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. 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