Guys today im going to go throug how to design a proffesional level lab power suply for our lab,so lets start with simple LM317 Based dessign ok.
19.22 pm me back again .first of all weneed specs for our project,
As per my case i need my power supply need to have.
1.25V to 10V voltge adjestment.
Softwre controll
Lcd display 16x2
0mA to 1000mA current adjestment.
Battery powered.
(Data logger to collect data with time)
Those are the basic specs that we need for this project.this is the first step of our designing steps...if you already have an idea.
So after that we nned to select what type of components that we are going to use on the final design.im using both SMD and through hall components in my design. Im using SMD prts because i need this power supply to be small as much as possible.
Ok then,lets try to select components to our project.....for a typical power supply project the main part is the voltage regulation part.i choose LM317 regulator because it is a jelly bean part..also its about 0.10/= in sri lanka.also LM317 is able to handle voltages bitween 1.25v to 36v whicjh is well within our specs.and it can handle currents upto 1.5A through the regulator in TO220 package.
If we are happy with that regulator we can download that data sheet and get the formulas to use it in our applications,
According to the datasheet of the LM317 the minimum voltage required to lm317 is about 1.25v+2v at the room temperature. So we need to maintain atlease 3.25v at the input side of the regulator to maintain regulation.
Ok then we nned to look at the upper boundery ,its 10V from our specs, lets keep 5v gap to that because the reguulator drop and series resistor drops. Totally we need 15Vminimum to obtain the regulation,we are going to powerup this device from the mains,in that case we have to use transformer to drop the voltage to 15-17v.then we hve to use 1.5A bridge rectifire to convert AC to DC.then need to use filter capacitors to smooth the waveform.lets caklculate those values later.
For now we are just selecting the components and making a sketch of the design. Also we need to add proper fuse to the primarry of the transformer.
