Hi guys and gals,

I bought a gamma2 and I'd like to plug in to the wall and use the trasit to send it data across toslink to avoid ground loop issues. Does anyone have any recommendations as to what to buy for a 5v 300mA supply to use with it.

Sorry for the dumb question but I'm having no luck finding one and I'm obviously looking in the wrong place.

Per other's recommendation, I usually try to find a Jameco Reliapro supply from Jameco Electronics - Electronic Components Distributor

I know that MisterX recommended one to me at one point but I can't put my finger on it right now (it was years ago). I also swear that there used to be one listed on amb's site but it's not there now. Fudge.

LM7805 with a small transformer and a couple of caps?

Try this - Jameco Electronics JAMECO RELIAPRO: GPU410500500WD00: Power Supplies & Wall Adapters

If that link doesn't work search Jameco's site for 164101.

Jameco (in Pars' link) has some suitable adapters, and I have used one of them with my Gammas. However, they don't come with the correct DC plug at the end. So, you'll also need to replace the plug with one like this (1.3 mm inner diameter):

https://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&productId=71192&catalogId=10001&storeId=10001&krypto=9x3mj8umRTrXCB%2BGZ5pvwLsdJ1BWPBy3UDbP1UYKq3uAqAskOQ8PphM6icQyNTrz0%2FZ5Innm1r7r%0D%0AaqLZPx6BDA%3D%3D&ddkey=https:StoreCatalogDrillDownView

Make sure you have the + and - polarity correct when you replace the plug!!! Center pin is positive, outer sleeve is ground.

If you want to go totally DIY, this is a perfect task for a TREAD or Sigma25. Tangent has a lot of information on the TREAD page on how to power it with any cheapo wallwart (about 9VDC would be the right kind to use; thrift shops are loaded with these). I just put my TREAD in-line with the power cord in a small Radio Shack box:

Try this - Jameco Electronics JAMECO RELIAPRO: GPU410500500WD00: Power Supplies & Wall Adapters

If that link doesn't work search Jameco's site for 164101.

Thanks for the recommendation. That looks good. Then I buy the correct connector? AMB recommends:

CONN POWER PLUG 3.5MM X 1.3MM - PP3-002D

Damn this is a bit of a PITA

Hmm, would a regulated USB charger work? iirc, the gamma2 can run off usb power

Hmm, would a regulated USB charger work? iirc, the gamma2 can run off usb power

that was my first thought but I've had no real luck finding one. According to the builder the usual ones are rather noisy.

I am also in need of a power supply for my gamma2, not sure if I'm going to use a sigma25 or sigma11. On the flip side, a power brick would be a simple re-termination and wouldn't take too much effort. hmmm.

I thought I saw in the gamma2 thread some mention of using the sigma25. And I think that MisterX also builds these? Correct me if this is something that doesn't work.

No, the S25 is a definite option.

No, the S25 is a definite option.

It's definitely an option, I'm just trying to figure out how to best mount it into the slightly taller Box Enclosures case. I was thinking of picking up a panel from onlinemetals.com cut to rough size then dremel'ing and filing until it's the right size and shape for it.

Slightly OT, but it seems like there's a popular opinion amongst some on the other site that the S25 is audibly inferior to the S11 for the Gamma1/2. I was a bit perturbed at this opinion to say the least. Perhaps it's just that my brass ears can't tell the difference when switching power supplies around on a dac

but it seems like there's a popular opinion amongst some on the other site that the S25 is audibly inferior to the S11 for the Gamma1/2. I was a bit perturbed at this opinion to say the least.

I wouldn't be too concerned about that, considering the calibre of some of the people claiming massive differences

Well I guess it's decided that I'll get the brick and reterminate it but I'm going to hold off on ordering until after I'm really sure that the USB power thing I have doesn't do the trick.

Well I guess it's decided that I'll get the brick and reterminate it but I'm going to hold off on ordering until after I'm really sure that the USB power thing I have doesn't do the trick.

My concern would be how to check the output of the USB power thing and make sure it's acceptably regulated?

My concern would be how to check the output of the USB power thing and make sure it's acceptably regulated?

Well I checked and it outputs up to 1A so that's covered but as you say there is no real way to know it's acceptably regulated. I assume that to work with USB devices it has to meet some voltage range specification much like the USB ports out of the computer, therefore I figure it should be ok.... ?

Edit: Looking at the gamma1 website it looks like there are voltage regulators on the USB port anyway so now I'm really not worried about that. It looks like it needs to be regulated if I want to use the power plug.

Edited May 5, 201016 yr by Dreadhead

While doing some initial testing with my gamma2 I found that that most of the usb power things I have are unacceptably low on voltage. In fact, one was actually putting out 4.3v!

That's some interesting regulation going on there. Did you measure with and without load?

I was measuring off the pins on the usb header of the gamma1 board so there should have been a slight load. I did not measure without load. Some did come close @ 4.7-4.8 but not even my motherboard put out a proper 5v. I was

Any idea what the line voltage was during those tests? Would have been fun to have the supply hooked up to a variac to see if it was simply getting too little ACin to regulate or if it was regulated to the wrong voltage. Also, any idea what the USB spec actually requires? Maybe 4.3VDC is really ok?

From the spec sheet, under 7.3.2 Bus Timing/Electrical Characteristics, in table 7-7 DC Electrical Characteristics:

High-power Port 4.75V Min / 5.25V Max

Low-power Port 4.40V Min / 5.25V Max

So I'm going to guess the ones I tested that were low were designed for low-power devices. Didn't know there was a difference, so I guess I'll have to take a look at the labels vs output. I've always assumed that usb = 5v so it's good to know there's a wide range that the spec allows for.

Odd. My HP laptop and two HP docking stations all hit almost exactly 5V.

Perhaps I'm just really unlucky. I'll do some more measuring tonight and see what I get.

Any idea what the line voltage was during those tests? Would have been fun to have the supply hooked up to a variac to see if it was simply getting too little ACin to regulate or if it was regulated to the wrong voltage. Also, any idea what the USB spec actually requires? Maybe 4.3VDC is really ok?

With the assistance of a sacrificial usb cable I did a bit of measuring. It seems that the voltage dips when hooked up to the Gamma2, but with no load they all measured roughly at 5v. For reference, my wall AC measures 120.1V.

Computer:

No load: 5.01V

Gamma2: 4.45V

Usb hub:

No load: 5.15V

Gamma2: 4.59V

Garmin usb power brick:

No load: 5.02V

Gamma2: 4.84V

I already threw out the cheapy usb power brick that measured 4.3V with the Gamma2 so I can't measure that one.