Feeler: EZ Tube Lunch Box

[dipfrik]

Hey Ian,

Did you check with Brian Sowter what the maximum output level of the 2K4:600 output transformer would be?

no, what do we need?

I have made a simple sketch of the side of the cassette holding the toroid.

Is it somewhere on the Emporium?

Cheers, Sven

 

[ruffrecords]

Hey Ian,

Did you check with Brian Sowter what the maximum output level of the 2K4:600 output transformer would be?

no, what do we need? [

The Carnhill and Edcor transformers will provide +26dBu into a 600 ohm load but we don't really need that much. For most people +20dBu into 600 ohms would be plenty.

I have made a simple sketch of the side of the cassette holding the toroid.

Is it somewhere on the Emporium?

Cheers, Sven

oops, forgot to add the link:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/lunchbox/toroidlayoutscaled.jpg

Cheers

Ian

 

[dipfrik]

I cannot find room for your auxiliary power  regulator PCB.

It's a 30x50mm small PCB? If i look at my last 3D model (included reserved space for fuse/switch/br) there should be space in several different positions or orientations. If the actual real estate of utility pcb is a problem, we can design a different size of the pcb that fits after we have all components inside the module.

We are so close, this won't be a problem

Cheers, Sven

 

[ruffrecords]

I cannot find room for your auxiliary power  regulator PCB.

It's a 30x50mm small PCB? If i look at my last 3D model (included reserved space for fuse/switch/br) there should be space in several different positions or orientations. If the actual real estate of utility pcb is a problem, we can design a different size of the pcb that fits after we have all components inside the module.

We are so close, this won't be a problem

Cheers, Sven

OK, I'll leave that up to you.

Cheers

Ian

 

[dipfrik]

OK, I'll leave that up to you.

Trust me!

Did you check with Brian Sowter what the maximum output level of the 2K4:600 output transformer would be?

Brian emailed me, that we now use a variant of the 5069, which can handle a maximum level of +24dBu at 50Hz.
Again same footprint like the mic input transfomer but a little bit higher. 44mm now (24mm is the mic input transformer).
I ordered two now.

Cheers, Sven

 

[ruffrecords]

@Sven,

I have used the Sowter 5069 before so I am happy with a 2K4:600 variant - and it has the same footprint as the mic transformer - well don#e Sven.

I have just finished testing thee LD1084 LDO regulator with a 12VAC transformer. I filled the test rack with 6 channels of amplifiers and connected up the 12V supply. The load current measured 2,9 amps which is a little above he expected 6 x 0.45 = 2.7 amps. I left it running for half an hour. The chip got hot but the heatsink only got warm although it is  a much bigger one than the one we will be using. Now I will fit one to the first power supply board which has he correct heatsink and run the same test.

I have also finished the design of a 4 module motherboard for use in the lunch box. I have ordered some prototype boards which should be here in a couple of weeks.

Cheers

Ian

 

[buildafriend]

When I first saw this thread I found the concept intrigueing. I just wished it could handle more units than two. 4 sounds like a better option to me. But, I'm not everybody, or you.

Best,
-JP

 

[dipfrik]

...I just wished it could handle more units than two. 4 sounds like a better option to me.

What do you mean with that?
What can't handle more than two?
The PSU?

Cheers, Sven

 

[dipfrik]

I have just finished testing thee LD1084 LDO regulator with a 12VAC transformer.

Cool!

The correct heatsink is identically with the 1st iteration of the PSU or?
It was this one here or:
http://octopart.com/510ab0500mb(to3)-abl+heatsinks-2601278

Cheers, Sven

 

[ruffrecords]

I have just finished testing thee LD1084 LDO regulator with a 12VAC transformer.

Cool!

The correct heatsink is identically with the 1st iteration of the PSU or?
It was this one here or:
http://octopart.com/510ab0500mb(to3)-abl+heatsinks-2601278

Cheers, Sven

That is the right one.

Cheers

Ian

 

[ruffrecords]

I have fitted an LD1084V to the heatsink that fits on the power supply board and run it loaded with 4 amplifiers. The heatsink only reaches 42 degrees Celsius after more than 30 minutes running so it looks like the LDO is going to work. I could not test it with 6 amplifiers because the 12V transformer I was using was not man enough for the job.

Cheers

Ian

 

[dipfrik]

I have fitted an LD1084V to the heatsink that fits on the power supply board and run it loaded with 4 amplifiers. The heatsink only reaches 42 degrees Celsius after more than 30 minutes running so it looks like the LDO is going to work. I could not test it with 6 amplifiers because the 12V transformer I was using was not man enough for the job.

That's awesome or?!
Ok, i need to find a different source for warming up my loft over christmas.

So where are we standing now? Could you start making 1st run of the pcb's?

Only to not get lost in all the things we discussed the last days regarding the new psu pcb design, you did the following:

- squeezed and moved some components
- deleted terminal and replaced them with pads
- reduced the size of the 48V smoothing cap
- deleted the heatsink for the 48V supply

and now the important change:

- you exchanged the LM338 with an LD1084V

So the architecture as well as the resulting BOM is exactly the same like the 1st revision, besides the new regulator.
Ok, and that it's now all fitted on a eurocard.

Am i right or missed i something?

Thanks, Sven

 

[ruffrecords]

Hi Sven,

That is an excellent summary of the current state of the 3U power supply PCB layout. Now I am confident we can use the original heatsink I will do a final check and order some prototype PCBs.

Cheers

Ian

 

[ruffrecords]

@Sven,

I left the power supply on all night last and this morning the heatsink temperature was 44 Celsius so I think it is safe to say that it reached thermal equilibrium. That was with the lid off off so I could get the thermocouple in but I would not expect it to rise more than another 5 degrees with the lid on. To be sure, I will see if I can keep the thermocouple in there and screw down the lid.

Cheers

Ianm

 

[dipfrik]

@Ian

Don't tell that your insurance company!

Great results!

Cheers, Sven

 

[ruffrecords]

@Ian

Don't tell that your insurance company!

Great results!

Cheers, Sven

Good point!! I managed to find a way to get the thermocouple out with the lid on. Last night my friend Bob came round for his weekly recording session so we ran it all evening and checked the temperature whenever we remembered. By the end of the evening it had levelled out at 55 degrees - a little higher than I had expected but still perfectly acceptable.

It occurred to me that, since we are now using a TO-220 regulator, it can be mounted directly to the cassette because the mounting screw is insulated from the TO-220 tab by the mounting kit. So we might be able to eliminate the big heatsink altogether. We could then use the space to mount your utility regulator PCB.

I have ordered a Fischer 28HP HB style cassette from Buerklin but it is currently on back order. I hope to order the 3U PSU PCB tonight.


Cheers

Ian

 

[dipfrik]

We could then use the space to mount your utility regulator PCB.

I told you we will find space!

I have ordered a Fischer 28HP HB style cassette from Buerklin but it is currently on back order. I hope to order the 3U PSU PCB tonight.

I tried the same. Hopefully they are back in stock before christmas.

Cheers, Sven

 

[dipfrik]

So i finished the utility pcb right now.
I need to figure out how i can make a panel of these, because it will lower the cost dramatically at the end.

Here is the final pcb. I will run a batch starting next monday.

Cheers, Sven

 

[ruffrecords]

@Sven,

Will you be making these PCBs yourself?

Cheers

Ian

 

[dipfrik]

@Sven,

Will you be making these PCBs yourself?

Cheers

Ian

That was the idea or?

Cheers, Sven