Linear power supply for Cambridge iD100 iPod dock?

[swt61]

So how difficult would it be to design an upgraded linear power supply for this unit? Something that might fit in a smallish Hammond case maybe.

[spritzer]

Rather simple. The 2A input current is a bit odd but something like a LM338 based psu would work for this.

[swt61]

Do you have it built for me yet Spritzer, it's been 30 minutes since i posted?

Seriously though, does that come in kit form somewhere, and I guess I'd need to alter it some?

Edited February 1, 2012 by swt61

[swt61]

So here's a kit designed for the iD100 at $168.00. I'm guessing I could handily beat that price by designing and building my own (read as conning Marc into designing and helping me build it).

http://welbornelabs.com/pspod.htm

[ujamerstand]

wasn't that the guys who damaged somebody's HE60 and HEV70 with their aftermarket PSU?

[swt61]

Ouch, really?

I'd want to build my own anyway.

[cobra_kai]

Most expensive thing would be the transformer, probably $20-30. Everything else is cheap: the lm338, 5 diodes, a couple resistors, a pot to fine tune the voltage, and 3 or 4 caps. Probably cost about 40 bucks. You could do even cheaper if you got an ac to dc wallwort and just passed the dc through the lm338.

Or you could go crazy and build a sigma 11

[swt61]

I like the Sigma11 idea actually.

[morphsci]

I have a Wellborne labs PSU for my Squeezebox Touch. Have had it for longer than the Touch and it still works great.

[swt61]

Fitz and I are discussing using a STEPS, as a bulletproof, easy and cost effective solution.

[johnwmclean]

I like the Sigma11 idea actually.

Is that rating 2A rating continuous?

Edited February 2, 2012 by johnwmclean

[swt61]

John I'm looking at the manual, and I don't seem to find that answer to that question.

http://www.cambridgeaudio.com/assets/documents/iD100_Users_Manual.pdf

[johnwmclean]

2A for the an S11 may be pushing it thermally...

Edited February 2, 2012 by johnwmclean

[cobra_kai]

Well I was assuming 2A would be peak. But even if we use the equation on the sigma 11 site

Tj=Ta+(P*(Rjc+Rcs+Rsa) allowing a fairly warm ambient of say 40 degrees C

100<=40+(7*2*(3.3+.48+2))

100<=40+(7*11.6)

100<=121

This is using the Bergquist isolation pad and the recommend aavid onboard sink, as well as the recommended 7V over desired regulation.

So I guess you're right 2A continuous would be too much. But if it's more like 1A continuous and 2A peak then the junction temperature is only 80.6 which would be fine, and I seriously doubt something that specifies a 2A supply will be pulling 2A continuously. And you could always use offboard sinks for better cooling. The 7V above regulation is rather conservative as well.

Edit: I just took a peek at the manual and under the technical specs section it states up to 12W power consumption when charging a device, so it should never be pulling more than 1A continuous.

Edited February 2, 2012 by cobra_kai

[grawk]

I used a sigma 11 to power an apogee minidac happily, which uses WAY more power than this.

[johnwmclean]

I used a sigma 11 to power an apogee minidac happily, which uses WAY more power than this.

Hang on there your getting WAY to technical

Yeah, looks like the 2A rating is a very conservative peek. Which thus puts the S11 back on the menu.

[mrarroyo]

Would a sealed lead acid battery with a charger/maintainer work well?

[MASantos]

The battery could work but if you want any reasonable playing time between charges you would have to get a somewhat large one which not only increases price but also footprint.

If you're looking for something more elaborate than a lm338 based PS, you can also check the placid from twistedpearaudio which has been put on par with the O11. I'm not sure of it's current capabilities though, but it comes as a kit and they also sell the transformer, so you could save on shipping costs.

[swt61]

So after some back and forth with Fitz, I've decided that a STEPS will do what I want, without getting too crazy. Fitz has an extra board laying around and I'll stuff it into a Hammond case and be done. Thanks for all the help and suggestions!

[Beefy]

Doesn't the iPod draw up to 1A of current while charging? The 2A might not be so ridiculous after all......

[swt61]

For the sake of higher fidelity, I'll probably set the iD100 so that it doesn't charge, and charge the iPod seperately. But that's a good point.

[cobra_kai]

The manual still says 12 watts max when charging, which would be 1A @ 12 volts

[Pars]

Would a sealed lead acid battery with a charger/maintainer work well?

I wouldn't be a bit surprised if the SLA was noisier than a sigma11 or other well designed AC PSU.