hi, browsed through a thread and finally got an idea where to get the components from.

but one thing is that i'm not familiar wif KL,
can someone provide more details on where is the so called Jalan Pasar?
or even better, the exact address...
thanks

hi all, got an assignment going on here tat need some idea from you guys...
i need to construct a DC power supply which takes in 240v AC and have 3.3v,5v,12v,15v and 24v output which have max 250mA load...

here is my idea :

1) AC line -> fuse -> transformer (step down to 24v) -> rectifier -> capacitor (filtering) -> resistor to further step down to each lower value

2) AC line -> fuse -> 5 transformer (step down to each of the 5 values) -> capacitor -> output

which one is practical?

5 transformer seems a lil too ridiculous...
since lecturer say there is only one physical output needed, i choosen to use reostat.

anyway, when it says 24v DC output, does it means peak voltage, RMS voltage or average voltage should be 24v?

dello,

what is the U1 opamp doing?

i think it is better to separate the motor control circuit and the resistivity sensing circuit.

make ur U2 opamp into an upper bounded comparator that output on or off signal into the motor control circuit.

as u asked why the voltmeter didn't work, i couldn't see a problem with the voltmeter part of the schematic. try to make a measurement to make sure the voltmeter is fine, and proceed to verify ur component one by one.

if you're building the prototype using breadboard, make sure all components is inserted properly that they are completely a closed circuit.