Electronics > Projects, Designs, and Technical Stuff
DIY DC Current Probe?
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Jeroen3:
Alright. That did not become clear on the Tindie page. However, I've gotten into the rabbit hole now.  :scared:

update:
I'm currently looking into putting two 14500 lithium cells inside.
They should fit, since two normal AA's do. I also considered two eneloops, but that would be only 2.4 Volts, which is too low and would require an additional booster.
A protection IC would become unnecessary with nimh though. Both 2x1900mAh nimh and 800mAh li-on carry equal Wh's.
fuzzoli:
For folks in the US and who might be interested in the Sensitec sensors mentioned in Reply #2, I contacted and Sensitec and they pointed me to https://buy.fwbell.com/current-sensors.html

They only carry the 4000 series sensors, but this series requires just a single 5v supply (as opposed to the +/- 15v supply of the other sensors).

...free shipping too!  :-+

-Frank
Jeroen3:

--- 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 ---
Got the board in. Very unstable switching, thing burns 250 mW without load.
Replaced chip, thing works for a while, then starts burning 100 mW... still without load.  |O

1: V+
2: V-
4: Vin


Sch/Brd:

--- End quote ---


--- End quote ---


Now, I got to admit I didn't have 3.3uH, so I used 4.7uH. It works great at 2.5Vin, but at 5V it's awful.
Jeroen3:
Progress! Replaced the inductors for 2.2 uH. More stable. Seems I really need to get close to the 3.3uH, which isn't in my lab kit.

I now got ripple at around 200 mV, at around 1 KHz. Still significant ringing though.
When I test only the positive I get under 60 mV ripple, so I have to fix some Vin issues I guess.

Also spotted one mistake already, Vneg feedback is taken from before the capacitors.
Jeroen3:
As I said, switchmode power supply topology near or above 1 MHz is a bit voodoo I'm not master yet.
I replaced the output capacitors 2x10uF ceramic 1206 for 4x 4.7uF X5R 0805.
Massive improvement.
I also disabled power-saving mode on the TPS65130 to make it behave more predictably.

Ripple is now low and high speed that even the location of the probe has significant effect.
There is still a small peak, I think this is the diode.

On below image:
1: V+
2: V-
4: Vout (0A)

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