# Calculate total Amp in a system

Greetings.

I bought a Circuit Scribe pen that writes with non-toxic conductive silver ink. The ink can hold up appliances up to 900mA.

my question is how do I calculate the total Amp of a(my) project that consist of Arduino, gas sensors, lcd etc.

Better to put the hardware together then measure the current draw with a DVM.. .

my question is how do I calculate the total Amp of a(my) project

You take the current draw for each and add them up. In your case just do the heater on the gas sensor and the back light on the LED, the rest are small by comparison.

The ink can hold up appliances up to 900mA.

Yes an I believe in fairies as well.

What you need to know is the resistance of that ink not some spurious current rating. What does "hold up" mean anyway?

I think he means can pass up to 900mA. This however depends on the thickness of the trace.

Weedpharma

weedpharma: I think he means can pass up to 900mA. This however depends on the thickness of the trace.

Weedpharma

. . and the width!

Russell.

I suspect at 0.9A the ink is losing a lot of volts... I've never seen a conductive ink that can carry real power.

What are the practical uses of conductive ink? Is it for "real" use or is it a gimmick?

The rear window demister in your car is printed on the glass with "liquid wire".

But I think this is about printing/drawing circuit board tracks. https://www.youtube.com/watch?v=WDsBO_tCLlk Leo..

It depends on the ink as well.

The carbon type can carry very little current.

The silver stuff is very much better and much more expensive.

It can be used for repairing demisters as advertised PROVIDED said demister has not been laquered over.

I have never found it particularly useful for pcb type work though.

JimboZA: What are the practical uses of conductive ink? Is it for "real" use or is it a gimmick?

I used it for the elements of this TV antenna which I designed many years ago.

I've also seen it used for keyboards where crossovers were printed along with the tracks. Much lower manufacturing cost than pth board.

Russell.

Hi,
Important question, what voltage are you expecting to push the current through the track?
What is the application?

I see those pens as temporary fixes to PCB track repairs at <12Vdc.

Tomâ€¦

@JimboZA

What are the practical uses of conductive ink? Is it for "real" use or is it a gimmick?

I've used the paint to repair cracked flexible (plastic) PCB traces.

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