greeeg 460 Posted November 19, 2015 Author Share Posted November 19, 2015 The masking tape sorts out the melted edges on the mylar. I've not tried kapton myself, but I believe it should cut well. The slightly misshaped holes are entirely down to the fact that I'm cutting small rectangles at very high speed. Asking the head to turn a fast sharp 90 degree corner means there's some overshoot and vibration. You'd never really notice if the shape wasn't so small. Raster engraving might solve this completely. I've not looked into this as it's certainly good enough for my current needs. LQFP and QFN worked fine last night, despite using crusty old paste that I thinned out with flux and stirred with a screwdriver! I'll try taking some photos. Yes, I have never tried to run mine that fast yet. I've done more work on the code. Not worrying about code size. ( It is around 7kb, basically maxing out the poor G2452. ) And the forward voltage diode drop voltages for anyone interested. bluehash, cubeberg and terjeio 3 Quote Link to post Share on other sites
terjeio 134 Posted November 20, 2015 Share Posted November 20, 2015 The masking tape sorts out the melted edges on the mylar. I've not tried kapton myself, but I believe it should cut well. The slightly misshaped holes are entirely down to the fact that I'm cutting small rectangles at very high speed. Asking the head to turn a fast sharp 90 degree corner means there's some overshoot and vibration. You'd never really notice if the shape wasn't so small. Raster engraving might solve this completely. I've not looked into this as it's certainly good enough for my current needs. LQFP and QFN worked fine last night, despite using crusty old paste that I thinned out with flux and stirred with a screwdriver! I'll try taking some photos. Just tested, the masking tape works fine. Now I need to buy some solder paste... I ran my laser at 500mm/min with 1200PPI so I did not get any deformation - I think pulsing the laser while cutting allows me more freedom in selecting the speed as the power delivered to the cut remains more or less constant even when the head is accelelerating/decelerating. Quote Link to post Share on other sites
Fred 453 Posted November 20, 2015 Share Posted November 20, 2015 @@terjeio Glad you got it working. My setup is just on/off, so I needed to turn the current to minimum and the speed to maximum. Perhaps if we've got any more discussion on lasers and stencils we could start another thread rather than taking this one further off topic. Quote Link to post Share on other sites
greeeg 460 Posted November 25, 2015 Author Share Posted November 25, 2015 Received the new display PCBs This is the first time I've done a proper panelised design. Managed to wrangle kicad into doing that without any major issues. The boards are routed between and v-scored along each end. Nice fit for the LEDs. The old PCB the spacing was a tad tight. I wanted to have the soldermask removed on one of the PCBs. I even specifically mentioned it in the panel file along with describing the V-score lines, that I wanted no soldermask on the bottom PCB. However they put it on anyway. I guess it's to reduce costs (due to more gold plating). But I did pay extra for the ENIG plating. Seeed's custom service for PCB errors is pretty flaky, I doubt I can get any refund/replacement. (It could also be to do with seeed's rules on panelisation and different designs) Quote Link to post Share on other sites
greeeg 460 Posted November 25, 2015 Author Share Posted November 25, 2015 Did not have enough parts to assemble an entire panel. I've done 2 boards. Seems to work as expected! I am currently adjusting the brightness by a PWM into Output enable. The new PCB does not feature a MCU. It has a breakout for the major signals the display needs Serial IN Serial Clock Data Latch Output Enable Reset Vcc Gnd This means to complete this clock I will need a second daughter board. I deferred getting it fabbed because I had not designed it. This is the next step. I also need to decide if I want a dedicated RTC. Or maybe a GPS?! (I like the idea of not needing to set time.. Having the controller board separate means I can potentially make a more advanced control PCB, maybe an ESP8266? Pulls down internet time. oPossum 1 Quote Link to post Share on other sites
greeeg 460 Posted January 22, 2016 Author Share Posted January 22, 2016 The first boards I assembled used wire links across the MOSFETS because I did not have any in stock. I designed the PCB to use SC70. (SOT323) does anyone know why there are SC and SOT part numbers? Turns out I tried using some SC59 (SOT 23) P channel's This did not work, at all. Turn out I wired the Source and the Drain the wrong way around. Because I hardly ever use P channels, and basically everything about them is inverted from N-channels. The way I have wired it in my original circuit, the current will always flow though the body diode!! So I've re-designed the PCB and sent it for fabrication. I still have not decided on a control board for this yet. I felt that I was reaching the limits of the G2542 after adding a date display to the software RTC with automatic day of the week calculation. the old board also did not feature a proper buzzer. limiting it's function for an alarm clock. Exploring the ESP8266 space is interesting, due to it's ultra low cost. If this desk clock is wall powered using wifi could yield some cool features, Notifications/ internet counters. The trouble is programming/coordinating cloud services to perform the task. Quote Link to post Share on other sites
San66 0 Posted February 4, 2016 Share Posted February 4, 2016 May be easy to use four MAX7219 modules like those: http://aliexpress.com/item/J34-Free-Shipping-1pcs-Red-MAX7219-LED-Dot-Matrix-for-Arduino-Microcontroller-Display-Module-Control/32400801615.html Quote Link to post Share on other sites
greeeg 460 Posted February 7, 2016 Author Share Posted February 7, 2016 May be easy to use four MAX7219 modules like those: http://aliexpress.com/item/J34-Free-Shipping-1pcs-Red-MAX7219-LED-Dot-Matrix-for-Arduino-Microcontroller-Display-Module-Control/32400801615.html MAX7219's are interesting parts, however if I want to avoid the grey market. these parts are VERY expensive. digikey stock them at $14 AUD a piece. Also the displays I'm using are smaller 1.9mm leds, vs 3mm. and the SOIC package sadly would not fit Quote Link to post Share on other sites
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