Onboard Multimeter ?

[Young Jedi]

Hello

I am a teacher

I would like to use a LED screen built in circuit breadboard

To display the continuous current


So the student can change value of resistor and the amperage or voltage will show on the LED screen

English not first language - apologys

 

[Gobbledok]

You can buy digital panel meters which run from 5v and measure and display voltages. With a shunt and a couple of resistor changes you can measure current.

You can also get analog panel meters which require no external power.

Search eBay for 'panel meter'.

 

[Young Jedi]

You can buy digital panel meters which run from 5v and measure and display voltages. With a shunt and a couple of resistor changes you can measure current.

You can also get analog panel meters which require no external power.

Search eBay for 'panel meter'.

Like here?

**broken link removed**

This good right?


Thank you!

 

[Young Jedi]

You can buy digital panel meters which run from 5v and measure and display voltages. With a shunt and a couple of resistor changes you can measure current.

You can also get analog panel meters which require no external power.

Search eBay for 'panel meter'.

That is it!!!

Thank you much!



What if I subtract the current from 2 separate terminal block ?

Like 2 of these: https://www.radioshack.com/product/index.jsp?productId=2103986&CAWELAID=107594021

Each has panel meter

Then you subract - or addition - the current (amps) for each ??

To display elsewhere?

Thank you much!!!

 

[Mr RB]

That should work fine.

Another option for the amp meters might be to get small multimeters as sometimes these can be cheaper than panel meters.

 

[bountyhunter]

That should work fine.

Another option for the amp meters might be to get small multimeters as sometimes these can be cheaper than panel meters.

That was my thought. I see cheap DVMs at Harbor freight Tools for $3.

 

[Young Jedi]

Hello - is this possible to do?



What if I subtract the current from 2 separate terminal block ?

Like 2 of these: https://www.radioshack.com/product/index.jsp?productId=2103986&CAWELAID=107594021

Each has panel meter

Then you subract - or addition - the current (amps) for each ??

To display elsewhere?



I want to show the students math between circuits

 

[Gobbledok]

Hello - is this possible to do?

What if I subtract the current from 2 separate terminal block ?

I don't think it is possible to do just with the meters themselves (unless you find a tricky meter) but you can do it with a simple op-amp circuit.

 

[KeepItSimpleStupid]

Reminder guys, that the typical Ammeter is a SHUNT ammeter, which means it will drop a small voltage when measuring current, stuff won;t add up properly unless you measure the voltage across the shunt and the added resistor. The Voltage burden is USUALLY in the specs.

A more complex method is to use a feedback ammeter. Pretty easy to design for currents below 10 mA or so. When your above 1 mA then lead resistance starts to get in the way of an accurate measurement.

Measuring the voltage across and the current through the resistor is the way to go for low value resistors. When you place a 10 m meter across a 10 Meg resistor, then it won't measure properly. It's a lesson in itself.

You can also indirectly measure the input Z of meters with a series potentiometer, a voltage source and an ohmmeter.

The Harbor Freight voltmeters are really cheap. They just don't turn off automatically.