Voltage Regulator PCB design review

[bulletbolt]

Hi all,

Here I have a project for voltage regulator. This is designed to use in small boats where you would need 12v dc power supply for ancillaries.

It's not a perfect design and sometimes I get various faults, some of them are mystique. If someone, who has more experience with voltage control, could have a look and tell their opinion would be highly appreciated. This is not something I do o n daily basis so need experts advice

Here's the schematics:



The questions I have raised is:
What's the limiting AC input
What's the maximum DC load

All this PCB being fitted into small rectangular alu tube and fully potted.

Ideas and thoughts please

 

[KlausST]

Hi,

Against your headline this is not a PCB design....you just show a schematic.

And to be honest, I don't know how you think this should work.
What about a little bit of explanation?

There are a log if proven voltage regulators, why do you do it this unusual way?
What worries me the most: how can the output be DC if the input is AC...and there is no output capacitor.

Klaus

 

[betwixt]

T1 is a supply regulator to the op-amp. It seems to be configured as a comparator with output controlling conduction through the triac.

Just a guess: this is normally driven from a generator attached to the engine and the missing output capacitor is actually a lead-acid battery, hence the unusual output voltage. It's cheap and dirty but probably works. The design looks to be from the early 1980s.

Brian.

 

[bulletbolt]

T1 is a supply regulator to the op-amp. It seems to be configured as a comparator with output controlling conduction through the triac.

Just a guess: this is normally driven from a generator attached to the engine and the missing output capacitor is actually a lead-acid battery, hence the unusual output voltage. It's cheap and dirty but probably works. The design looks to be from the early 1980s.

Brian.

You are right Brian. This is normally driven by engine's alternator. I am aware of missing output capacitor. The challenge is to either improve current design using today's solutions and parts (I would expect it would be cheap too)

Any suggestions? Main point being it has to be very very compact.

 

[BigBoss]

I recommend you to use a modern Step-Down Regulator without any trouble.
These kind of circuits are troublesome ..

 

[betwixt]

But.... beware that modern SMPS require a reasonably well filtered DC input. You can get 10A (my guess at the maximum output current of the present circuit) switch mode regulators for very little cost and they are very efficient. You would have to add a fairly large capacitor (~10,000uF) after the bridge rectifier but the remainder of the circuit would be small and run cool.

example: **broken link removed**

Brian.

 

[bulletbolt]

So from what I see it may be much easier to just find much better design voltage regulator. Anyone have a source of 15-30VAC to 15VDC voltage regulator? Must be very compact..

 

[FvM]

The usual method for alternator control is modulating the excitation winding. Apparently it's not possible here, e.g. PMAC machine.

Small size means no filtered DC input to the down converter. I further presume that you have a battery, so no output filter is needed.

If you want to optimize the generator efficiency, buck PFC could be a solution. Otherwise phase angle control like implemented in the original design s still an option. Power dissipation could be reduced by using an active MOSFET bridge rectifier and MOSFET switch.

 

[bulletbolt]

The usual method for alternator control is modulating the excitation winding. Apparently it's not possible here, e.g. PMAC machine.

Small size means no filtered DC input to the down converter. I further presume that you have a battery, so no output filter is needed.

If you want to optimize the generator efficiency, buck PFC could be a solution. Otherwise phase angle control like implemented in the original design s still an option. Power dissipation could be reduced by using an active MOSFET bridge rectifier and MOSFET switch.

To make it clearer, I have attached picture of current PCB size. Any chosen design would have to fit within same dims as I have lots of enclosures (and they were costly).