Adding LED meters to the LA-2A

[rob_gould]

Hi all,

I'm hoping to add LED meters to my dual LA-2A build.  This is a subject that doesn't seem to have been covered onthe forum as most people go for a more vintage build, but I want a more contemporary look for mine.

There are loads of LED VU meter plans on the internet utilising LM3914N chips and similar, and Igor released a cool looking LED meter a couple of years ago, but I'm interested to know if these can just be dropped into the circuit in place of the standard meter, or are there other considerations?

Any advice on this would be much appreciated.

Thanks,

Rob

 

[SSLtech]

Tricky.

That is to say, not trivial.

For one thing, you negate all galvanic isolation from the output transformer.

For another, the Gain Reduction would be next to impossible to substitute in directly, since it is used in a bridge with some serious DC voltage involved.

Could it be done? -Certainly. but a complete redesign of the GR display circuit would be absolutely imperative... and the units output balance would probably be significantly compromised, unless you built a driver circuit.  -With these considerations in ind, it's perhaps clearer to appreciate why nobody has done this.

Keith

 

[thestudio]

How about using the Nixie tube meter which I believe there's a kit available somewhere on this site? I was also looking into something different..... 8)

 

[rob_gould]

Tricky.

That is to say, not trivial.

For one thing, you negate all galvanic isolation from the output transformer.

For another, the Gain Reduction would be next to impossible to substitute in directly, since it is used in a bridge with some serious DC voltage involved.

Could it be done? -Certainly. but a complete redesign of the GR display circuit would be absolutely imperative... and the units output balance would probably be significantly compromised, unless you built a driver circuit.  -With these considerations in ind, it's perhaps clearer to appreciate why nobody has done this.

Keith

Haha OK.  A little more complicated than I was anticipating.  Thanks anyway for giving me some advice on things to read up on!

@thestudio : I think it was Igor who  created that pcb, and though he may still have boards, I believe the Nixie tubes themselves are extremely hard to get hold of

Cheers

Rob