Audiocom super regs

[t.]

I recently brought a Cambridge CD4 from a bootsale for £5, it obviously is faulty so when I got it home I whipped the lid off to just make sure nothing was burnt etc, when I powered it up it seems the laser unit is shot but I noticed one of these fitted inside http://www.soundlabsgroup.com.au/aud..._regulator.htm
Its been to set output +15v which seems to be supplying a couple of 5v regs on the board.
I wondered if its possible to adjust its output to 5v? I wanted to try it to supply the 5v to the SAA7310 in my modified Arcam Alpha5

Cheers

[JonHarrison]

Hi,

Its been to set output +15v which seems to be supplying a couple of 5v regs on the board.
I wondered if its possible to adjust its output to 5v?

Absolutely. You need to change the value of one resistor to adjust the feedback level on the comparator. If you look on the board you should see a resistor piggybacked on top of a capacitor - that's the one. I think the reference is 2.5volts so the resistor across the cap needs to be the same value as the one down to the 0V.

Cheers,

Jon

[t.]

Thank you Jon, thats good to hear

Have you tried one of these regs? I currently use ALW super regs everywhere else but regarding size the Audiocom one would nicely for the SAA7310 inside my Arcam

[JonHarrison]

Hi,

Have you tried one of these regs?

I do have a positive and a negative - which I bought out of curiosity. I haven't put them in anything yet though.

I currently use ALW super regs everywhere else but regarding size the Audiocom one would nicely for the SAA7310 inside my Arcam

Did you get them direct from Andrew or from another source ? How much were they ?

I'd like to do a more compact pcb of my own with SMT components when I get time, based on Walt's design with a few tweaks.

Regards,

Jon

[t.]

Originally posted by JonHarrison
Hi,



I do have a positive and a negative - which I bought out of curiosity. I haven't put them in anything yet though.



Did you get them direct from Andrew or from another source ? How much were they ?

I'd like to do a more compact pcb of my own with SMT components when I get time, based on Walt's design with a few tweaks.

Regards,

Jon

I've had a look and can see theres a few smd resistors, theres only one mounted ontop of a cap its tiny and I can't see the value very well, it looks like 028, thought it was 820R but the 2 would be upside down, measuring it (on circuit) reads 1k.
Other bits is a Darlington transistor, NE5534 op-amp and a 2.5v reference diode.
The track is so squashed up I'm struggling to see what goes where just need to find the one which goes to earth.

I brought two of my ALW regs directly from Andy a couple of years ago ready built up (I can't remember exactly how much they was, about 30 quid each I think) I'll try and find out if you like.
The others was bare boards I got from a group buy from here with a few of the ZL caps anyone interested in a jung regulator pcb group buy?

[JonHarrison]

Hi,

(I can't remember exactly how much they was, about 30 quid each I think) I'll try and find out if you like.

I was curious as a pair just went on Ebay for £122 which I thought seemed a bit over the top ! £30 each seems more reasonable given the cost of the components.

From my notes 820R would give 12V output but I could be wrong.

Per-Anders Sjöström's regulator looks good too !

Cheers,

Jon

[t.]

Hi Jon,

Well you know how crazy the bidding can get on E-bay

I really don't think the resistor is 820R, normally a 820R smd would be marked 821 I'd have thought, I've no idea what 028 means
I've measured it again and it does read 1k on my meter but because its still in circuit is it possible this is affecting the reading?

Do I work the resistor values out the same as a normal adjustable reg?
One of my ALW super regs is set to output 5v so If I can get this one set to output the same I could compare them it should be interesting although I doubt it would come close to Andy's.

I'll have a look at Per-Anders version

Cheers,

Leo

[JonHarrison]

Hi Leo,

I've measured it again and it does read 1k on my meter but because its still in circuit is it possible this is affecting the reading?

Possibly but it's probably just in parallel with the cap which will (should!) have a very high DC resistance.

Do I work the resistor values out the same as a normal adjustable reg?

To maintain the output level, the voltage between the comparator inputs should be 0 i.e it needs to match the voltage derived from the reference. So

Vout / Vref = (R1 + R2) / R1

Where R1 is the resistor on top of the cap and R2 is the one to the 0V. Find the value of R2 and you can work out what R1 needs to be, or work out R1 at the moment and you can scale it accordingly.

Cheers,

Jon

[Fin]

Hi Jon

Do the Audiocom Super Regulators require any special implementation or is it best to just drop them in as a replacement to the existing regulator without changing any of the surrounding components?

The regulators supplying the TDA1541A in my Arcam CDP have various values of capacitors before and after them. Should I retain those values?

[Sonusthree]

Hi,
I have used a few and dropped them straight in as 78xx replacements in my CD player. I think these regs are aimed at the intermediate tweaker. After all, if I knew a litttle more at the time then I would have probably built my own. I kept the original caps because they were Oscons but you may have old or low quality electrolytics in your player. The beauty of these things is that they are so easy to install but I don't think I'd ever pay full list price for them when there are so many DIY alternatives.

Best regards,
Martin.