nfhw / tinycurrent Goto Github PK

For a future revision, It would be really convenient to have the input terminals (current) available on a screwless terminal block, to avoid the requirement for bulky banana-plug test cables, when testing breadboard (and similar) circuits.

Something with a pitch of at least 5 mm would be ideal.

The README.md document specifies the J5 battery connector as "2-pin 1.25 mm JST ZH style male header".

However, JST ZH connectors have a 1.5 mm pitch.

While the J5 male PCB connector does have a 1.25 mm pitch, the "JSP ZH" designation is wrong.

It might be a good idea to update and possibly specify a supplier and part number for a female connector matching J5. I believe the connector is colloquially called "JST 1.25" or "Micro JST 1.25" (Chinese suppliers), although I have not been able to locate the connector in the JST product catalog.

Maybe I am overlooking something here, but you use a 10mOhm resistor as shunt for the mA range. The slide switch has (according to the datasheet) <20m Ohms.
You specify an accuracy of 0.1% in the mA range. How should that work if the "reference" resistor is in series with the switch? Even for 10m Ohms for the switch, the error is huge?

I see your tinycurrent connect to oscilloscope with BNC to BNC adapter. I see BNC connector( male type) on AliExpress.

Is it possible to use this connector instead ?
If use this connector ,BNC -BNC adapter don't need.

There might be a stability issue when introducing capacitive loads. This is seen on one of Dave's EEVBlog videos about the uCurrent (https://www.youtube.com/watch?v=1VlKoR0ldIE).
The issue seems to be a design mistake. Which is the output 270 Ohm resistor being INSIDE the feedback loop of the last amplifier. When capacitance is introduced on the output, it will create a big phase shift (depending on the capacitance value) and can make the amplifier oscillate.
The solution is to simply remove the 270 Ohm from inside the loop and place it directly on the output before the binding post.
For people that already have Dave's uCurrent or the tinyCurrent version, the easiest fix is to remove the 270 Ohm resistor, bridge the pads, make a small cut on the output track going to the binding post and solder the 270 Ohm there.

For those of us, who do not have Altium designer installed, it would be really useful to have the TinyCurrent circuit schematics available in PDF format files.

Why is there a thin track between -IN terminal and the sense resistor?