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| Power supply ripe for the picking |
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| Antuan:
Hi! Yes, I still have it. After testing some other models I found on Amazon.es I finally decided to keep it, as the others were lower quality. Also the two USB and the memory entries are really handy. This one is well built, although it has this issue with the clock. I'm willing to fix it, but I think I don't have the knowledge —I'm a web dev, with basic electronics knowledge—, or even tools: I have a multimeter and a logic analyzer, but I don't have an oscilloscope, which I suppose will be needed to test the installed xtal in this unit. But if someone helps me to go through the process of fixing it, I may borrow an oscilloscope to do it. This would be an interesting project! A. |
| tangodown281:
Hi A., I'm a CNC machinist/programmer by trade, but dabble in electronics as a hobbyist, so I'm probably not the best guy to ask, but I'll offer what I can. Unfortunately, I don't have time to dig into mine right now and search for components. As always, a schematic would help a lot, but it's highly unlikely you'll be able to find one. To add to what I said before, if they are using a crystal, which I kind of doubt, it will be in some type of metallic, 2-lead package and marked with a "Y" on the PCB. The most common type I'm familiar with looks kind of like a tiny metallic stick of butter laying flat on the PCB. It may also be a metallic cylinder, probably upright like a standing thru-hole resistor. It could be an oval can, like ancient RC car crystals, or even a wide, flat package like an IC. It would probably have the frequency printed right on it. They may also be using some flavor of the ubiquitous 555 IC timer, which will likely be in an 8-pin SMD package and will probably be marked with "555" on it. If you can identify the manufacturer, you should be able to find a data sheet online with a pinout that shows you what they use to set the output, which in this case obviously needs to be 1Hz for one pulse a second. If they're using this method, it's possible that simply the tolerance of the external components used to tune the output frequency are enough to throw it off - or they just used the wrong value. I would expect this to be somewhere near the 7-segment LED driver for the right-hand yellow bank. There is probably more information available online regarding the 555 timer than there are pictures of Kim K's butt, so I won't go into details here - I'd probably just make it more confusing anyway. If it does turn out to be a 555, try not to let the little woman see you Googling it or you'll have to explain the difference between an astable and monostable multivibrator, and why you're Googling it in the first place. Again, HTH, and if not, maybe try posting another thread that someone with more knowledge than I will see. Pretty sure there's somebody out there that would know exactly how they're getting the 1Hz signal without even looking at it. |
| markrages:
I found a weird transient problem with my HM305P. It looks like this: I put the full description and a script to duplicate it on my github at https://github.com/markrages/hm305p_problem It seems a combination of changing the output voltage and applying a load causes the a pretty big transient in output voltage. For $DAYJOB I work with bicycle components, and I was testing an electric derailleur at different supply voltages. Well, a derailleur is basically an open circuit when nothing is happening, and suddenly a sizeable load while the shift happens. So I made my script to activate it at different voltages and noticed it seemed to be brownout-resetting, even when the supply voltages were all within normal operating range. I will not divulge how long it took me to troubleshoot this... I am curious if anyone else has seen similar on the different rebrands and output ratings of this supply. Or maybe I am just unlucky. |
| Erhannis:
I made a remote control interface for my HM305P, in Flutter (and python). https://github.com/Erhannis/HM305PRemote/releases/tag/1.0.0%2B1_android https://github.com/Erhannis/HM305PRemote/releases/tag/1.0.0%2B1_windows Read the instructions; there's a few things to install. Screenshot attached. |
| trcm:
I hadn’t seen this post Mark, but will try my HM305P and see if I can reproduce. |
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