Lightspeed Attenuator

**aquapiranha** · 08-10-2009, 14:38

Originally Posted by Tripmaster

Yes, I purchased my enclosure from Maplin. The case costs £10 and is more than large enough for the project.

Puffin and I purchased 25 (unmatched) LDRs from Farnell and we haven’t noticed any audible imbalance between them.

The circuit is really simple to construct and for me the sound is simply stunning!

You’ve got to build one.

I would love to when I have my current project out of the way. Are there any plans that a dunce like me could follow?

Puffin wins as he has a nice LED, not one of those retina scorching blue death ray thingies...

**Puffin** · 08-10-2009, 15:27

[QUOTE=

Puffin wins as he has a nice LED, not one of those retina scorching blue death ray thingies...

[/QUOTE]

Here is the circuit diagram. Looks easy, but you have to work on the underside and of course the components are arse about face so to speak. Left connections are Right and vice versa.

**Tripmaster** · 08-10-2009, 16:58

Originally Posted by aquapiranha

I would love to when I have my current project out of the way. Are there any plans that a dunce like me could follow?

Puffin wins as he has a nice LED, not one of those retina scorching blue death ray thingies...

If that's the only reason, I'm happy with that

**alb** · 08-10-2009, 17:08

I fancy building one of these sometime, just out of curiosity.

If anyone wants to start or join in a group buy for LDRs......i'm interested.

I'm afraid mine will have a blue led as well. I've got a stock of em somewhere.

**aquapiranha** · 08-10-2009, 17:45

Originally Posted by Tripmaster

If that's the only reason, I'm happy with that

Indeed it is the only reason by which I judge any piece of equipment!

I am all for the 'group buy' thing unless anyone here has some spare?

I assume it will be a bread board job as there are no commercially available circuit boards?

Ta.

**Tripmaster** · 08-10-2009, 18:58

Originally Posted by aquapiranha

Indeed it is the only reason by which I judge any piece of equipment!

I am all for the 'group buy' thing unless anyone here has some spare?

I assume it will be a bread board job as there are no commercially available circuit boards?

Ta.

Unfortunately I don't have any spare as I am also building one for my dad. Just buy 4 LDRs + 1 as a spare. I'll post the Farnell part numbers shortly.

I think Uriah's current group buy has finished, but has plans for another towards the end of the year.

**aquapiranha** · 08-10-2009, 19:51

Thanks Richard, I get most of my parts from Farnell already.

I will not be able to start it for a few weeks probably as I am still finishing the speakers and boxing the Sure amp.

EDIT:

I see it uses a 5v supply. Is this flexible at all? reason I ask is that it may be noce to try a battery powered version? Ta

**Puffin** · 08-10-2009, 20:01

Make a battery supply with a 9v battery, 2x 2200 caps and a 7805 regulator. Voltage should not exceed 5 v. I'll post a daigram of how to wire it if you need it.

**Tripmaster** · 08-10-2009, 20:18

I started off with a 9v battery/7805 supply, but stuck to GeorgeHIFI's psu.

**alb** · 08-10-2009, 20:30

Looking at the blurb, it needs a low impedance source, which probably means i couldn't use it after a tube pre.
I would have to connect the DAC output to it, which is ok, except it would then be for CD only and not be a replacement for the pot in the amp.

Perhaps not as useful as i first thought.

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