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#286
Stammheim said:
Hi guys,

is there a reason why NOT to take a 2x18V transformer?

As I'd like to take only one encapsulated transformer for 2 LPUHP I'd like to take one with more than 65VA, so a bigger 2x18V transformer is easier to get in Germany.

Thanks,

Stammheim
Click to expand...



Another question:

I have a Hypex SMPS600 with +-65V and an encapsulated transformer with 2x35V.
Which power supply would you guys recommend to run the LME49830 amps? Some quick answers would be very cool!

Thanks,

Stammheim
 
#287
Stammheim said:
Hi guys,

is there a reason why NOT to take a 2x18V transformer?

As I'd like to take only one encapsulated transformer for 2 LPUHP I'd like to take one with more than 65VA, so a bigger 2x18V transformer is easier to get in Germany.

Thanks,

Stammheim
Click to expand...

I wouldn't suggest this. Transformers are usually rated at full load for secondary voltage, which means your 18VAC transformer will be closer to 19 or 20VAC with only the idle draw of the LPUHP amp. This will definitely exceed 25VDC on the primary caps, and causes higher dissipation on the regs by forcing them to drop more voltage under full load.

You could get away with it if you increase the voltage rating on the caps before the regs, but that will reduce their capacity and really only works against you.

You need to think of these amplifiers a little differently because they have fully regulated supplies. Using a massive transformer doesn't buy you anything, because the voltage regulation happens downstream anyhow. As long as the transformer is large enough to keep the voltage on the unregulated side higher than the voltage on the regulated side plus the dropout on the reg at full power, then you're good to go. Having the unregulated voltage sag at full load is actually desirable as it reduces the dissipation on the regulators under full load. The little 30VA Amveco potted toroids I tested with were perfect as they sagged to about 20VDC unregulated at full load, meaning the regulators were still fully functional, but only had to dissipate a few watts because of the low voltage differential.

If I were you I would use two smaller 15VAC transformers before I considered trying to share a larger and higher voltage one.

As for the LME amp, I personally would use the Hypex supply over the potted transformer, but that's just me.

Cheers,
Owen
 
#288
Hi Owen,

I'm playing around with a script that uses Octopart API in Python and can generate the equivalent Mouser SKU from a list of digikey SKUs ... if I get some time to finish it off I should be able to send you something for Mouser part numbers later in the week if that is helpful (though my script won't look for equivalent components that Mouser doesn't stock ... )

Cheers,
Chris
 
#289
hochopeper said:
Hi Owen,

I'm playing around with a script that uses Octopart API in Python and can generate the equivalent Mouser SKU from a list of digikey SKUs ... if I get some time to finish it off I should be able to send you something for Mouser part numbers later in the week if that is helpful (though my script won't look for equivalent components that Mouser doesn't stock ... )

Cheers,
Chris
Click to expand...

Very cool!

It would be great if you could plug in the DK parts in the BOM and spit out the results.

If there are only a few parts not in stock, I can always go through the list and pick substitutes.

Cheers,
Owen
 
#290
Hello to everybody,

while waiting for the pcbs I tried to create myself "by hand" the Mouser boms.

You should find at the following url the complete Wire SE-SE Mouser project:
https://it.mouser.com/ProjectManager/ProjectDetail.aspx?State=EDIT&ProjectGUID=4a74defa-4d0c-4617-81f6-23b11acac5d3

Please check it carefully (I am not an expert DIYer), but the material should be exactly equal to the DJkey BOM of Owen.

I tried also to prepare the PSU BOM, but in this case I found some problem in finding the equivalent material (in particular the caps).
Your help is really welcome in checking the list and suggesting the correct caps:
https://it.mouser.com/ProjectManager/ProjectDetail.aspx?State=EDIT&ProjectGUID=c20230c2-dd05-4e7c-a252-e84f959230f9

I hope these links work

northernsky
 
#292
Ockam said:
Hello,
Could someone point me to the circuit schematics for SE-SE?
I've found ones for PSU and LPUHP but not for SE-SE.
Thank you.
Click to expand...


There is a build wiki linked in the very first post of this thread. It has the schematics attached to it ... I think it also includes the schematic for the V1 PSU design, so ignore that. There is also a BAL-SE schematic but I think Owen didn't worry about it for this batch.
 
Last edited:
#294
opc said:
Very cool!

It would be great if you could plug in the DK parts in the BOM and spit out the results.

If there are only a few parts not in stock, I can always go through the list and pick substitutes.

Cheers,
Owen
Click to expand...

Hi Owen,

I've sent you an email with the result for the LPUHP BOMs (all versions). I thought I would email to minimise the number of variations of the BOM that are floating around the forum - to save confusion.

Unfortunately only about 50% coverage for direction 1:1 matches between the stores.

Later in the week I will see how I go with the other BOMs.


Cheers,
Chris
 
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