| Electronics > Projects, Designs, and Technical Stuff |
| DIY DC Current Probe? |
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| 0xdeadbeef:
--- Quote from: Jeroen3 on October 01, 2017, 04:49:38 pm ---I think it's going to topple over when you attach a BNC. It'll be a pita. --- End quote --- Well, maybe. Probably not in the actual use case where the scopes are placed quite a bit above the loads. And the scope will not even be connected all the time. That's what the LEDs are for. Besides, I could just define one of the sides as bottom. Or use a larger footprint off-the-shelf case. So IMHO this isn't really a problem. --- Quote from: Jeroen3 on October 01, 2017, 04:49:38 pm ---But, today I think made a power supply circuit with a TPS6513x. Now on to sourcing all the components, which isn't easy if you are not a business. Then create test board, since I never get these right first try. --- End quote --- Plus it's QFN which is something I try to avoid. Plus DC/DC stuff is much more critical regarding component selection and layout compared to a charge pump. Side note: AFAIK a USB device is only allowed to draw 100mA until it negotiated its current draw with the host. |
| Jeroen3:
Ah, yes. You have a workbench with equipment shelf. The LED's are a nice touch though! I'm might steal that. I am aware of the 100 mA uninitialized limit, but I have yet to encounter a host that implemented it strictly. But I could search for a USB charge controller nonetheless. The QFN doesn't scare me, the DC/DC frequency does. I was able to approach to the recommended layout reasonably well with 0805. The 2.7 to 5.5 Vin of the TPS65131 should be suitable for 3xAA or one 18650. I'll have parts and boards over ~2 weeks. The Chinese have holidays... |
| Leo Bodnar:
--- Quote from: 0xdeadbeef on October 01, 2017, 05:21:48 pm ---Side note: AFAIK a USB device is only allowed to draw 100mA until it negotiated its current draw with the host. --- End quote --- Bad news, bad news! USB "device" is only allowed to draw 100mA for 100ms and then possibly 2.5mA if you convince the judges that it is really a device. Even this is very Zen because how the device with no data pins would know that there is no activity on the bus data pins? Good news is that nobody knows this (let alone follows the rules.) USB Lava lamps are allowed to draw 600mA if they are pretty. Leo edit: evidence is attached |
| Jeroen3:
Just use this cable and you get twice the power >:D |
| Jeroen3:
So. I took out Fusion 360 and did my first 3D to see if it would fit in a box. Finding a box was hard, I wanted to use a profile extruded enclosure, but these would become large if they could house the 23mm of the CMS3005 sensor. Later I found this Hammond box, with mounting stubs in the lid. It looks like it would fit. The 3D was even harder. Never touched such software before. But it's great, I like it. |
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