LEDs on 5.7v heater tap

Hi all,

I've been fitting a Sifam AL19 retro VU meter into a preamp project. There are two surface mount LEDs inside it, with s 330ohm CLR between them, and positive/neg wires to hook up to a power source. The sticker is a bit damaged but I believe it says 12v, 20mA.

The power transformer has an unused heater tap that used to be for a first stage valve - I moved this to a 6.3v tap, freeing up the 5.7 (0.3A) tap.

I would like to use this to power the LEDs. I have hooked the VU meter up to a 9v battery and it lights fine. Last night I hooked it up to the 5.7v tap with a small circuit I found on another site consisting of a 1N4004, a 10uF electrolytic cap across the supply and a 200ohm resistor (didn't realise there was a CLR inside the VU at this point).

The VU lights up fine, perhaps a very very subtle flicker.

I'm wondering - is this safe to run, and is there a better way to get DC to run the light from this tap?

Thanks for any input

Attached the small circuit I used

It's OK, you can use a bigger elco so the flickering will be much smaller or nonexistent. 

moamps said:

It's OK, you can use a bigger elco so the flickering will be much smaller or nonexistent.

Click to expand...

Great, thankyou

I assume 47uF should be more than enough

Also, is the rdrop resistor unnecessary in my application?

You don't need  additional Rdrop if it is installed already  in the meter and is sufficient for the voltage you are using.

moamps said:

You don't need  additional Rdrop if it is installed already  in the meter and is sufficient for the voltage you are using.

Click to expand...

This is great, thankyou 

My worry was that the 5.7v wouldn't be enough. I'm curious why it would need 12v for a pair of surface mount LEDs

Nominal current of 20mA for LEDs is quite high, the luminescence is usually just fine when this current is much lower as you see.