1. Home
  2. Hobby Electronics Basics
  3. My power supply

My power supply

I'm working on making a power supply that supplies different fixed regulated voltages and also a + and - variable voltage (actually all the configurations I will have are +5, +8, +12, +15, +15 and +24 along with a + and - variable from 0 to 20 volts).

Now, I also plan on using an LCD to display the voltages and currents for each(but using one 24x1 LCD).

My question is how can I control for automatic "resolution" for the voltage meter? like I can use a fet(or maybe an op amp) to detect the voltage but I need some kinda variable resistor that I can controll with my microprocessor(which has build in 10bit ADC). I know there are ways to do this but I'm not exactly sure what I need... I'd like 4 places of accuracy from uA and mV to A(1.5A max) and V's(25V max).

I also have a fan in my case and I'd like to controll it depending on the temperature... what device will return the temperature in the case that I can use with my MCU to control the fan current?

Last thing I'm not to sure on is where to place my on off switch in the circuit.

right now I have mains->fuse->varistor->filtering->switch->transformer but it seems that I would want the switch right after the fuse?

Thanks, Jon

Reply to
Abstract Dissonance
Loading thread data ...

Buy an autoranging meter?

Good Luck! Rich

Reply to
Rich Grise

What do you mean by "4 places of accuracy"?

In any event, you seem to be mixing accuracy with resolution. You need to specify both.

Ed

Reply to
ehsjr

what I what I ment was 4 digits of precision. The accuracy is not a big problem the voltage should be stable enough so that I can get an accurate reading by adjusting a trim pot and using my DMM to match it... but it needs to be somewhat precise.

For example, say I am trying to set 7.43V's on the output but my measurements only give me a precision of 1V then I can't get that setting and my reading would be anywhere from 6.43 to 8.43 volts... way to much of a swing to be of any use.

If say, though when I use my perfect DMM to measure the voltage and its really 3.43 instead of 7.43 then my accuracy is wrong and I can change pretty easy(or should be able to by just adjusting a resistor(which would probably throw off the precision to some degree too though)).

i.e. accuracy corresponds to calibration which should be easy to accomplish... the precision is much more comlicated and depends on the components and circuits used. Although I suppose some circuits are better for accuracy too but it seems that it would be much easier to get adjust for accuracy than precision.

Jon

Reply to
Abstract Dissonance

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.