battery tester (help needed thanks!!!!!!)

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hi K7elp60:
sorri to bother you ! the 3rd question is that: instead of using a regulator i applied a +5V to the 10K fixed resistor then on the other leg i connect a 10K variable resistor (instead of potentiometer) then after the variable res. , connect it to gnd (series connection). then i calculated the small resistance res. (i used 1.2 ohms as i need ard 2A for my circuit).after calculating, i connected it to the source and then together with the whole circuit(the non-inverting i/p of the op amp series with a 1K res.) , i connect the circuit to the variable res. with respect to the gnd. i would like to ask that by varying the resistance of the variable resistor, i would change the value of the discharge current (drain current), am i right? then the 4th question is that i did a testing on the circuit that i built, instaed of using the batt, i used a power supply to act as my batt then i set to ard 12V. for the op amp part, i connect two independent pwr supp in series (set to ard 10V each) then 1 terminal is +10V, i connect to the vcc+ i/p of the opamp then the other terminal is -10V, i connect to the vcc- i/p of the op amp (i did not do anything to the other i/ps eg.offset null 1,2 , ..). then i switch on the power supplies and the pwr supp acting as the batt seems to be nt working(no voltage reading shown on the meter) and onli when i boost up the current of the pwr supp acting as the batt, then there will be voltage reading and the low resistance resistor will get burnt.
 
Oh, I forgot; if you need more than 1.5 A just change the LM317 for a LM338 and you can "burn" up to 5 Amps.

Ante :roll:
 
hi ante:
thanks for ur kind help i appreciate it
by the way:
does anyone know that whether an ADC0844 (A to D convertor) could be modified to produce the functions of a DAC?

hi K7elp60:
i have posted a few questions to you n i haven got ur reply

thanks all in advance!!!!!1
 
hi K7elp60:
regarding about the circuit u had provided earlier, what are the two 1K resistors at the +input and -input of the op-amp for? their functions? thanks in advance!!!!!!!
 
hi K7elp60:
can you tell the the functions and reasons why we need to put the two 1K ohms resistors to the '+' and '-' i/ps of the op-amp?
 
hi:
here is the circuit that i intend to use (attach)!!!! hence, i would like to ask wat are the two 1K resistors for? (their use and functions) and also how to calculate Vo (op-amp) ? then is V2 = Vs , V1 = VR4 ? pls reply urgent thanks very much!!!!
 
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