ammeter with the pic16f876A

[RYTECH]

I've used a Maxim 4172 to read various ranges of current. This IC uses a sense resistor to measure various ranges of current.

[RussMartin]

This does not appear to me to be a conventional metering circuit; it looks instead like a monitor for device voltage and current. U2 likely provides a reference voltage (it's a 3-terminal device, though, but is not used in any typical configuration).

I suspect that the two variable resistors are used to calibrate the circuit, and the zener diode (DZ1) provides overvoltage protection on RA0.

If you seek only to measure current, there are simpler circuits.

[Acetronics2]

Hi,

All details can be found here :

http://www.gpekit.com/pdf/mk3980.pdf

This is lots easier to understand how it works !!! ... an if reading Italian, ... The Nirvanna

Alain

[lutherblisset]

and what is the easier way to measure the current with the analogic ports of the 16f876?

[Acetronics2]

and what is the easier way to measure the current with the analogic ports of the 16f876?

You have the whole schematics ... and the kit explanations.

What further do you need ??? the program for free ???

Alain

[BigWumpus]

Where is the problem ?

1. You must know the maximum current.
2. You can choose your shunt (don't forget the heat!!!!)
3. You use a OPAMP as an amplifier for the voltage to maximum 5V for maximum current trough the shunt. I use an LT1490 (rail-to-rail) for 5V-supply and good quality.
4. Measure the voltage !
(I use the lm385-2.5 as a reference. I measure the voltage of one port an the voltage of a port with the lm385 on it to calculate the correct voltage, because the supply-voltage may be incorrect or spread widely. The normal 7805 is worse, I use a 78M05CDT instead.)

[lutherblisset]

can be the INA138 a good idea instead of the operational?it is a "High-Side Measurement Current Shunt Monitor, Current Output",it directly convert voltage to current