I have the BrianGT mini Aleph board set and would like to build an Aleph 40: 8 output devices, 6 on the output boards, and 2 on the main board. Yes, I know this will make the enclosure more challenging, but I have some ideas.
However, I have some questions. Sorry if these have been asked before.
1) The parts list I found says the bias resistors for the output board should be 0.47 ohms, but the schematic I found shows them as 1 ohm. Which is correct, and is this also correct for 8 output devices?
2) I don't have ZTX450/550, but I have BD139/140. Can I use these?
3) I have lots and lots of IRFP044. Any issues using these? Can I turn up the wick with these? How?
However, I have some questions. Sorry if these have been asked before.
1) The parts list I found says the bias resistors for the output board should be 0.47 ohms, but the schematic I found shows them as 1 ohm. Which is correct, and is this also correct for 8 output devices?
2) I don't have ZTX450/550, but I have BD139/140. Can I use these?
3) I have lots and lots of IRFP044. Any issues using these? Can I turn up the wick with these? How?
Maybe you meant Aleph 4?
Or Aleph 30?
Which one?
Huge difference in Pout and also Vcc, meaning different Trafo requirements.
You should start with the supply voltage, +/-25 (A3/ 30), +/-34 (A5), +/-48 (A4).
1. A3/ 30 uses 0.47 ohm source resistors, A5 uses 1 ohm
2. different pinout, ZTX is c-b-e, BD is b-c-e, it won't fit BrianGTs PCB, but if making own PCB no probs.
Some of the BC family have the same pinout as ZTX but in reverse, 180°, so will fit as long as you observe orientation, check datasheets.
3. great choice for a single pair output devices, like A3/30 on steroids.
Capacitance wise IRFP044 has almost twice the Ciss of IRF244 or 240 but if using only 1 pair instead of 2 or 3 it's all good.
044 has the highest Gfs which is a good thing in my book
BrianGTs PCB caters for mini-A and also any of the Aleph variants with up to 3 pairs of output MosFETs.
But mostly mini-A and A30.
Of course you can scale it up or down.
So you have a lot of flexibility there.
Watch out for the current source adjustments, you might need to play with a few resistors to set it right.
Search for an Excel spreadsheet here called "Aleph power" or "A-Power2" and play with it, countless options.
Or Aleph 30?
Which one?
Huge difference in Pout and also Vcc, meaning different Trafo requirements.
You should start with the supply voltage, +/-25 (A3/ 30), +/-34 (A5), +/-48 (A4).
1. A3/ 30 uses 0.47 ohm source resistors, A5 uses 1 ohm
2. different pinout, ZTX is c-b-e, BD is b-c-e, it won't fit BrianGTs PCB, but if making own PCB no probs.
Some of the BC family have the same pinout as ZTX but in reverse, 180°, so will fit as long as you observe orientation, check datasheets.
3. great choice for a single pair output devices, like A3/30 on steroids.
Capacitance wise IRFP044 has almost twice the Ciss of IRF244 or 240 but if using only 1 pair instead of 2 or 3 it's all good.
044 has the highest Gfs which is a good thing in my book
BrianGTs PCB caters for mini-A and also any of the Aleph variants with up to 3 pairs of output MosFETs.
But mostly mini-A and A30.
Of course you can scale it up or down.
So you have a lot of flexibility there.
Watch out for the current source adjustments, you might need to play with a few resistors to set it right.
Search for an Excel spreadsheet here called "Aleph power" or "A-Power2" and play with it, countless options.
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Hi Leadbelly,
You need to specify the schematics you are looking at and we are guessing at
what you are trying to do.
One thing to keep in mind is the max Vds of 60V for IRFP044 which places
a limit on your rail voltage.
Dennis
You need to specify the schematics you are looking at and we are guessing at
what you are trying to do.
One thing to keep in mind is the max Vds of 60V for IRFP044 which places
a limit on your rail voltage.
Dennis
The Aleph 4 is 4 x 6 = 24 output devices for 2 x 100W.
It's an easy enough build once you have matched the devices. There is nothing obsolete so that isn't a challenge.
It's an easy enough build once you have matched the devices. There is nothing obsolete so that isn't a challenge.