# 0-30 volts, 0-3amps Power Supply (Current Limeter)

Discussion in 'Homework Help' started by haprow, Jan 24, 2007.

1. ### haprow Thread Starter New Member

Aug 15, 2006
3
0
Hello to all...I need the knowledge of someone who cares...I am a BS Computer Engineering student. In this regard, our instructor give us a project about power supplies. Now, the specs we must be submitted is a

0-30 volts, 0-3amps laboratory power supply and

the design must have a current limiter that will not exceed on 3amps...

So, I was asking for a help or any suggestion that could give me an idea on how to do it. We are not allowed to use IC's regulator. The design must fully transistorized. And because of this, I am in trouble. I mean im tired looking at the net of some power supply according to our specs but all i have research for are using IC's.

Hoping for you the reply's guys! tnx anyway...tsups!

2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Hi,

There should be lots of literature on this, as linear supplies using discreet transistors were quite common.

I moved you to the homework section, as it seemed more to the point here.

Just as a starter, you'll need a pass element capable of dissipating the power. Let me recommend the workhorse from ages past, the 2N3055. It will need a sink for heat.

Given that, think about how to put the passer into controlled conduction. Come back with ideas and schematics, and we'll help out.

3. ### fanie Active Member

Jan 20, 2007
63
0
If we give you this with a spoon you won't learn anything and you would become a Computer Engineering parasite.

4. ### haprow Thread Starter New Member

Aug 15, 2006
3
0
wew enks! for the suggestion guys...now, my only problem is this...i am looking for a good current limiter circuit for my power supply. I already done with my volatage regulator using discrete transistors without IC's...the output is Vmax=31.1V and Vmin=0.67...but i'm still working on it to make the voltage drop to 0V and for my Vmax maybe i will use trimmer...any suggestion????

5. ### haprow Thread Starter New Member

Aug 15, 2006
3
0
View attachment TRUE_POWER_SUPPLY_SCHEMA.doc

here's my schema guys..but i have a little problem about limiting the circuit...if i short the circuit..this well tend to limit at 3amps but it makes the other devices or let we say the power transistors will be overheated! my heatsink is still useless...any suggestion or any solutions about this or maybe biasing of the transistors...i really need it urgently pls...help me