L-Adapter - Page 51

Salas · 17th May 2020, 09:23 AM

Quote:

Originally Posted by LaserGecko

Hi everyone,

Still trying to read through all fifty pages of this thread...

I ought to be able to power my RPi through the 5VDC connector on the HiFiBerry DAC+ Pro, correct?

Datasheet DAC+ Pro | HiFiBerry

Is there any reason to not use a two pin header connector? I have some with beefy wire from a few past Pi projects.

Thanks!

Looks like it should work, states connected in parallel, although I don't have personal experience with the HiFiBerry. Shoot a message to the HiFiBerry people just to make sure there's no hidden trap or limitation.

jameshillj · 18th May 2020, 11:06 AM

Hi Salas,
I have an idea to power my F6 amp at 2 x 1.7A/rail - by using the recent lt4320 fet bridge on the inputs (replacing the side diodes) and a bit of 'stuffing around, I can use 1 brd for +24v rail and the other brd for the -24 rail but each transistors will need to get rid of perhaps 25W per rail so locating the bigger heatsink is a problem

Is it possible to use longer wires (maybe 60mm) to mount the TO-247 pass transistor off board on a bigger heatsink without losing circuit performance?

Salas · 18th May 2020, 11:23 AM

Maybe not a no go because it initially worked on a breadboard with wires but for the printed board itself I never tried or seen extensions. The whole PCB can alternatively be mounted against a large heat-sink. Horizontally.

jameshillj · 18th May 2020, 01:22 PM

Thanks for the very quick reply

I have seen the "Smooth Like Butta" boards with quite long leads and surprisingly, it doesn't appear to create any problems but I'll try for the "pcb to heatsink" direct connection as designed first and maybe play around with variations later on.

The current Cap multiplier drops about 3 volts across the pass transistor so the L-Adapter is only about twice that (curiously, about the same as the AMB Sigma 22 regulator) - it'll be interesting to see what difference it makes ...

Salas · 18th May 2020, 02:06 PM

To make dual polarity with L-Adapter it takes stacking two for creating a virtual ground center point as you would do with batteries because only positive PCB type is available.

jameshillj · 18th May 2020, 02:29 PM

Ah right, forgot that - saves me 'stuffing' around with altering one of the boards for the -ve rail altho it's quite possible, apart from heatsink mounts for the diodes.

Thanks again - stay safe

Salas · 18th May 2020, 03:39 PM

Such a scheme demands an independent Tx secondary and an independent bridge feeding each L-A board. But you already have those things in mind I suppose.

Regards

jameshillj · 18th May 2020, 04:33 PM

Yeah, pretty okay for the right secondary voltage transformers to feed that fancy fet bridge and choice of caps, just need to get up off my A** and build it!

I have become really lazy with this Cov-19 confinement.

jameshillj · 18th May 2020, 04:38 PM

… sorry, for each rail, 1 x L-A brd, 1sec winding and 1 fet bridge.

shattered_dream · 18th May 2020, 08:40 PM

Stupid question : Can I use some wires to connect the NJW0302G ? I´m asking cause I want to mount this transistor at a big heatsink which will be mounted only a few cenimeters away from the board. Will be approximately 5cm of wire.

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18th May 2020, 11:06 AM	#502
jameshillj diyAudio Member Join Date: Feb 2005 Location: Melbourne	Hi Salas, I have an idea to power my F6 amp at 2 x 1.7A/rail - by using the recent lt4320 fet bridge on the inputs (replacing the side diodes) and a bit of 'stuffing around, I can use 1 brd for +24v rail and the other brd for the -24 rail but each transistors will need to get rid of perhaps 25W per rail so locating the bigger heatsink is a problem Is it possible to use longer wires (maybe 60mm) to mount the TO-247 pass transistor off board on a bigger heatsink without losing circuit performance?

18th May 2020, 11:23 AM	#503
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Maybe not a no go because it initially worked on a breadboard with wires but for the printed board itself I never tried or seen extensions. The whole PCB can alternatively be mounted against a large heat-sink. Horizontally.

18th May 2020, 01:22 PM	#504
jameshillj diyAudio Member Join Date: Feb 2005 Location: Melbourne	Thanks for the very quick reply I have seen the "Smooth Like Butta" boards with quite long leads and surprisingly, it doesn't appear to create any problems but I'll try for the "pcb to heatsink" direct connection as designed first and maybe play around with variations later on. The current Cap multiplier drops about 3 volts across the pass transistor so the L-Adapter is only about twice that (curiously, about the same as the AMB Sigma 22 regulator) - it'll be interesting to see what difference it makes ...

18th May 2020, 02:06 PM	#505
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	To make dual polarity with L-Adapter it takes stacking two for creating a virtual ground center point as you would do with batteries because only positive PCB type is available.

18th May 2020, 02:29 PM	#506
jameshillj diyAudio Member Join Date: Feb 2005 Location: Melbourne	Ah right, forgot that - saves me 'stuffing' around with altering one of the boards for the -ve rail altho it's quite possible, apart from heatsink mounts for the diodes. Thanks again - stay safe

18th May 2020, 03:39 PM	#507
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Such a scheme demands an independent Tx secondary and an independent bridge feeding each L-A board. But you already have those things in mind I suppose. Regards

18th May 2020, 04:33 PM	#508
jameshillj diyAudio Member Join Date: Feb 2005 Location: Melbourne	Yeah, pretty okay for the right secondary voltage transformers to feed that fancy fet bridge and choice of caps, just need to get up off my A** and build it! I have become really lazy with this Cov-19 confinement.

18th May 2020, 04:38 PM	#509
jameshillj diyAudio Member Join Date: Feb 2005 Location: Melbourne	… sorry, for each rail, 1 x L-A brd, 1sec winding and 1 fet bridge.

18th May 2020, 08:40 PM	#510
shattered_dream diyAudio Member Join Date: Dec 2009	Stupid question : Can I use some wires to connect the NJW0302G ? I´m asking cause I want to mount this transistor at a big heatsink which will be mounted only a few cenimeters away from the board. Will be approximately 5cm of wire.