AEM6000 Based 50W Amp

Attachments

  • SUZYJ-50W-R2-AMP-SCH.png
    SUZYJ-50W-R2-AMP-SCH.png
    41.5 KB · Views: 697
  • 123.png
    123.png
    124.5 KB · Views: 719
  • Like
Reactions: 1 user
My through-hole version using a double-sided board is attached. 68 x 85mm.
1. I have used BCXXX series for the non-Q3/Q4 signal transistor types which is why the pins are different.
2. The MOSFETs bolt thru the board so the whole board is also not hanging on the MOSFET leads. Also, no copper is under the board where the MOSFETs mount to provide the cleanest, flattest surface.
3. The drivers and MJEXXX's are able to be mounted on a central heatsink. Q16 and Q18 in particular, will probably need this heat sink at higher bias currents.
4. The dual FET input uses a SOIC8-W. I need to double check that case type.
5. All but the Zobel and output resistors are 1/4 W types which allows 8mm hole spacing.
6. Rail electro caps can be up to 12mm diameter.

I haven't done a final wiring check but expect that it should be 99% correct.

[/ATTACH]
 

Attachments

  • SuzysAmp.png
    SuzysAmp.png
    342.4 KB · Views: 472
Member
Joined 2004
Paid Member
tcd1963,

This looks very promising. I’m curious what SST404 substitute(s) are you targeting? I did not see a reply from Suzy to Prasi’s question of the same nature, although she said “sure” to 2N5564/5565/5566 - matched pairs of JFETs mounted in a TO-71 package.
 
Last edited:
The basic SST404 is the same dual FET device as in the original design. The U404 is the same but in a through-hole TO-71 can.

Some vendors say that the SST404 is obsolete but i haven't seen any say that about the U404. My design is for the SST404 which i think should still be available from some suppliers. Adding a few extra t/h pads for the U404 wouldn't be hard.
 
I did not see a reply from Suzy to Prasi’s question of the same nature, although she said “sure” to 2N5564/5565/5566 - matched pairs of JFETs mounted in a TO-71 package.

I know SST404s work well. U404s also work well, as they’re the same die in a different package. I have a whole pile of SST404s, and know I can get more from Future electronics whenever I want. For the record, I have to order these internationally just like you do.

I’m pretty patient, but not patient enough to pore through the data for every random jfet that people feel like suggesting. If you’re keen on a particular device then do the work yourself. Check the data, run a simulation. Even try building one around it.

Then you’ll be making a valuable contribution.
 
  • Like
Reactions: 1 user
Member
Joined 2004
Paid Member
My design is for the SST404 which i think should still be available from some suppliers. Adding a few extra t/h pads for the U404 wouldn't be hard.

tcd1963,

Thanks for your reply to my question regarding your targeted jfet device(s). The extra pads to allow for the use of U404 would likely help potential builders that have difficulty sourcing SST404 (if you plan to share our board design).
 
I have created 2 versions because i had difficulty fitting the narrow body SOIC8 around the TO-71 pins. It was possible, but I was not happy with the clearances. ...when it comes to making boards with tight fitting thru-hole devices, good eyesight, a steady hand and a very small solder tip are needed, none of which I can profess to have!

I will share the Sprint file tomorrow.

Also, I have changed the spacing between opposite TO-126 transistors where the heatsink could go. I dont have a standard spec for aluminium so this spacing might be too large. it is currently 2.78 mm which after taking into account insulators, is a fairly thick piece of Al. Suggestions are welcome.
TO-71.png

SOIC8.png
 
Last edited:
That's what I was thinking. The gate resistor values might need changing but otherwise the footprint could be the same.

The P and N channel Exicon dual die devices have quite different gate capacitances (unlike the single die devices) so the gate resistors might be quite different to each other and those gate capacitances are also much higher than the single die devices.