Bambozi Power Supply

[Ayne]

Another problem.
I want to measure 0 to 30 DC Volts with PIC16F877A and current 0 to 1A and want to show them on 7-Segment Display plz guide me in this way.
The problem is in hardware side,
I don't know how to maximize the input resistance??
and how to compatible 30 volts to PIC's ADC??
Any link, any tutorial or any thing else that can help me

 

[Nigel Goodwin]

Another problem.
I want to measure 0 to 30 DC Volts with PIC16F877A and current 0 to 1A and want to show them on 7-Segment Display plz guide me in this way.
The problem is in hardware side,
I don't know how to maximize the input resistance??
and how to compatible 30 volts to PIC's ADC??
Any link, any tutorial or any thing else that can help me

The one that's at the bottom of everyone of my posts!.

 

[Ayne]

Nigel Goodwin
The one that's at the bottom of everyone of my posts!.

Infact the problem is ur tutorials are in Assembly language but i will program my PIC in MikroBasic cuz i don't know assmebly. I just started assembly few days ago.

 

[Nigel Goodwin]

Infact the problem is ur tutorials are in Assembly language but i will program my PIC in MikroBasic cuz i don't know assmebly. I just started assembly few days ago.

Well assembly is more compatible, it's free, and it's what the PIC actually runs (or at the least the machine code represented by the assembler). There are many different versions of BASIC and C, and all of them are different. There are vastly more assembler examples on the net than any other PIC language, it doesn't take long to learn PIC assembler.

 

[Ayne]

Nigel Goodwin
Well assembly is more compatible, it's free, and it's what the PIC actually runs (or at the least the machine code represented by the assembler). There are many different versions of BASIC and C, and all of them are different. There are vastly more assembler examples on the net than any other PIC language, it doesn't take long to learn PIC assembler.

Yes u r right.
But i already said that the problem is in hardware side i mean in circuit side... not in programming.
I want to ask that how u guys measure 0 to 30Volts with PIC???
In both directions i mean +30 and -30 Volts??

How u guys measure current range 0 to 1 Ampere with PIC???

 

[Nigel Goodwin]

Yes u r right.
But i already said that the problem is in hardware side i mean in circuit side... not in programming.
I want to ask that how u guys measure 0 to 30Volts with PIC???
In both directions i mean +30 and -30 Volts??

Potential dividers and opamps - it's nothing PIC specific, and has no real bearing on the use of a PIC - you simply need to convert the input voltage (whatever it is) to a 0-5V signal (or 0-2,5V if you use a precision voltage reference). I'll give you a clue! - an opamp in inverting mode will convert a -ve voltage to a +ve one!.

How u guys measure current range 0 to 1 Ampere with PIC???

Exactly the same as you would with any meter, you measure the voltage drop across a shunt in series with the load. And again, you need to convert it to a 0-5V (or 0-2.5V) signal.

 

[Ayne]

Thanks Nigel Goodwin.

I attach circuits below, these are correct or need some improvement??
Want to improve performance

 

[Hero999]

There's nothing wrong with what you're suggesting.

You can save yourself an opamp though. Make R6 and R3 1Mhm: then you can remove UB.

Input impedance isn't too critical here since your supplies can both output a considerable current, so I wouldn't worry too much about using such high value resistors, 100khm: and 500khm: will more than do. You might also want to consider using precision resistors for this part of the circuit to make your readings as accurate as possible.

 

[Ayne]

With some improvements

Thanks Hero999.

Below i made some changes,
I reduce the values of input resistors.
I simulate this circuit in "CircuitMaker" Now input currnet is 50 Mircro Ampere.
It is normal current or need to increase input resistance???
C & C ????

 

[audioguru]

I think the opamps will oscillate like crazy with those capacitors shorting their outputs. Then they might even get so hot they will melt!
A TL072 oscillates with the small capacitance of only a shielded cable connected to its output.

 

[Ayne]

Improved.

I omit the capacitors from OP-Amp out put
and also add a zener diode. For protecting the PIC input leg.
Zener voltages is 5.6 voltages.
C & C are welcomes

 

[Hero999]

There'a nothing wrong with that.

The divider ratio for +V is different to -V, have you done this on purpose or is this a mistake?