Electronics > Beginners

HOW to add ameter RIGHT?

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digsys:
... or ... make up a tiny PCB with a dedicated ISense amp ie INA286 etc there are literally 100s. Use a fixed, say x100 gain, and a shunt to give 1-10mV MAX
That will get you 100mV > 1V DC op, where you use a Voltmeter.  If you already have a current meter, many / most can be converted to Volts by removing
the internal shunt. Worst case, it's not a huge cost. In higher current scenarios, I've simply picked 2 points on the output leads, and calibrated to that.
The temp accuracy is a bit drifty at high currents, but you're only doing 1A max.
Make up your own escutcheon with your own symbols etc .. always liked doing those.

gcewing:
I really don't think you need to worry about the voltage drop. 75mV out of 12V is about half a percent of error. No practical circuit is going to be anywhere near that fussy about its supply voltage, and your 7812 probably isn't going to regulate that accurately anyway when you put a load on it.

Some circuits do require a precision voltage reference, but they use a specialised component to produce it, they don't rely on the supply voltage being super accurate.

spec:
+ 001

You can do what you want with a three-terminal regulator, an opamp and a  voltage reference (zener diode).  But for a stabilized voltage of 12V it would be better to use a three-terminal regulator with an output voltage less than 12V. An LM317 would be ideal. If this approach is of any interest just say and I will post an outline schematic. By the way, the circuit would produce a stabilized 12V.

KaneTW:
Which MCU requires 12V+-75mV? I just can't imagine that being an issue, especially considering that accuracy adds significant cost to the PDN design.

perieanuo:

--- Quote from: 001 on October 24, 2018, 10:04:30 pm ---75mV is a BIG difference in some mc cases
The question is how to eliminate output voltage drop

--- End quote ---
No,it.s not.Sometimes 75 mV it can be noise, this will stop your TV to work?
Every microcontroller have Vcc larger margins.75 mV out of 12V it's negligeable, total acceptable error margin.
A good board should accept maybe 200mV or more variation in Vcc.
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