Voltage Regulator PCB design review

Thread Starter

bulletbolt

Joined Aug 5, 2018
5
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 PCB schematics:
Voltage Regulator B.png

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 :)
 

Hymie

Joined Mar 30, 2018
708
For a simple low voltage ac to dc regulator, the circuit is well over complicated.

I’m not even sure that it will work – I can see no reservoir capacitor (within the circuit) providing smoothing of the dc output.

My advice would be to find a far simpler circuit which is likely to be more reliable.
 

Thread Starter

bulletbolt

Joined Aug 5, 2018
5
Thanks for your post, Hymie. I cannot afford to use different circuit because I have already made quite few of these and have a stock of most components. Looking for a "fixing" solution or how to upgrade to more efficient and today's technology solution :)
 

Hymie

Joined Mar 30, 2018
708
The circuit design is somewhat unusual (to say the least) – in that the circuit is controlling the output dc voltage through switching one of the bridge rectifier ac inputs through triac (J1).

So in answer to your specific questions, the maximum dc current that the circuit can handle is the maximum current rating of the bridge rectifier or triac (whichever is less).

The maximum ac input voltage is similarly limited by the ratings of the bridge rectifier & triac; transistor T1 is regulating the voltage to the circuit op-amp. If an elevated ac input voltage causes excessive heating of transistor T1, then this may be the limiting voltage factor.

However I would not recommend that the circuit is used with an input greater than 30Vac, given that there is no isolation between input and output circuits.

Remember that having potted the complete circuit, the component heat dissipation will be considerably reduced, which may very well reduce the component spec ratings that are normally based on use in free air at 25C.
 

Thread Starter

bulletbolt

Joined Aug 5, 2018
5
Right, so I'm beginning to realize it would be better off to leave this design and use something else, something that's been developed using later technology and proven to be working. Anyone have a source of similar spec voltage regulator? Thanks in advance
 

ericgibbs

Joined Jan 29, 2010
8,733
hi bb,
The present design states 14.5Vdc, any reason why 14.5Vdc was chosen.?
Also what is the required maximum output current?

E
 

Thread Starter

bulletbolt

Joined Aug 5, 2018
5
Hi Eric,

The output is set to 14.5V to charge battery. So product should provide 14.5-15V DC output.

The output current must be 10A or more to charge the batteries efficiently.

I have attached picture of current design assembly - if I go with new design it would have to fit within same dims.
 

Attachments

ericgibbs

Joined Jan 29, 2010
8,733
hi,
If its just a simple battery charger, why is it required to fit in the same dims?

You originally said: This is designed to use in small boats where you would need 12v dc power supply for ancillaries.

E
 

Thread Starter

bulletbolt

Joined Aug 5, 2018
5
hi,
If its just a simple battery charger, why is it required to fit in the same dims?

You originally said: This is designed to use in small boats where you would need 12v dc power supply for ancillaries.

E
Ancillaries may be misleading, sorry, this device meant to charge the battery and ancillaries connected to the battery. That's how it works.

It has to fit in the same box as it does now - we already have enclosure stock so radical change would be too expensive..
 

ericgibbs

Joined Jan 29, 2010
8,733
hi,
I assume that you know, that your existing circuit, without any smoothing, the Vout is a full wave rectified sine wave, whose On period Phase time is controlled by the circuit.
E
 
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