voltage transients and regulators

SgtWookie

Joined Jul 17, 2007
22,210
That circuit will give poor regulation, as there are two Vbe drops between the regulator output and the actual circuit output. Vout will vary with load current, transistor gain, and the temperature of the transistors. Additionally, the emitters of all of the 3055's in parallel should have resistors, to balance the load between the transistors. Otherwise, they will pop like popcorn one at a time.

Feedback to the regulator needs to come from the output of the emitter followers. However, a 78xx series is not the regulator to do that with.
 
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Thread Starter

vini_i

Joined Apr 19, 2010
14
what is the best way to make a 14v regulated power supply that could make up to 20A and eliminates transients?

i've been reading about power supplies. from what i've read the best way to make a power supply is with a voltage regulator. it smooths out ripple and eliminates transients. i have not been able to find a voltage regulator that will by its self make 20A. after some research i found some references to hooking up regulators in parallel, but they have the same down fall of poor regulation. that's where i came across that wiring diagram. i was hoping that it was the answer i was looking for.

i'm looking to bench test car components. there is a power supply made for my application but its $550 and that's way too much for what i'm using it for. i was hoping to put something together for less than $100.

any thoughts would be greatly appreciated.
 
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Thread Starter

vini_i

Joined Apr 19, 2010
14
a sudden spike in voltage that sometimes happens in house hold voltage. The spike passes through a transformer, rectifer bridge and smoothing capacitors uneffected.
 

wayneh

Joined Sep 9, 2010
16,114
OK, well the voltage regulator ICs will take care of that, and not pass more than a tiny fraction of that noise. Others here will have to help you getting up to 20A. It shouldn't be too big a problem.

It would help to know what sort of devices you're planning testing (radios?, lightbulbs?, computers?).
 

Thread Starter

vini_i

Joined Apr 19, 2010
14
I work on a little bit of everything. Fuel injectors, radios, ignition control modules, ignition coils. Etc. But what I do most is flash engine and test engine computors. I normally just use a car battery but it's very inconvinient.
 

wayneh

Joined Sep 9, 2010
16,114
I think you could just use 12v for most of that stuff? Just get a beefy PSU from and old computer as Sarge has suggested. You can probably find one for free and the current limit will be written on it. It'll have it's own power cord, switch, fan, thermal and current protection, maybe a power-on indicator light, the works. It'll save you a ton of time. Sounds like Sarge knows how to goose it up to 14V if you really need that.
 
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