Akula0083 Light No3 - Dual TL494

[alejandroguille]

Anyone have the pcb?

[MarkE]

Anyone have the pcb?

I don't.  Akula hand wired his prototype.  I think that JB reverse engineered from photos of the prototype and or correspondence with Akula. 

[MarkE]

Anyone have the pcb?

I threw together a PCB design using the free tool express pcb.  www.expresspcb.com.  You can use this as a guide for a layout that you will etch yourself, or order boards from express pcb.  I replaced D3 - D5 with a second high speed diode.  I also added C6 - C10, more 0.1uF capacitors to decouple the stray inductances.  The switch connection is through TB5.  The flyback transformer connects through TB2 - TB4 left to right.  The dot orientation of the windings is marked in the silkscreen.  The power input is through TB1.

ETA: I found a mistake in the artwork.  TB5 pin 2 was shorted to the ground plane.  The fixed artwork is attached along with the updated schematic with the changes above.

[alejandroguille]

I threw together a PCB design using the free tool express pcb.  www.expresspcb.com.  You can use this as a guide for a layout that you will etch yourself, or order boards from express pcb.  I replaced D3 - D5 with a second high speed diode.  I also added C6 - C10, more 0.1uF capacitors to decouple the stray inductances.  The switch connection is through TB5.  The flyback transformer connects through TB2 - TB4 left to right.  The dot orientation of the windings is marked in the silkscreen.  The power input is through TB1.

ETA: I found a mistake in the artwork.  TB5 pin 2 was shorted to the ground plane.  The fixed artwork is attached along with the updated schematic with the changes above.

Thank you very much for answering!!!
and thanks for posting your updates so we saved time assemble.

[JohnnBlade]

in my tests i have seen that the IRF540n mosfets are better to use.

Greets JB

You should not have the collapses that you see.  I suspect a crossed connection that is not apparent in the schematic.  Disconnect MF2 and see if the circuit operates reasonably.  Then reconnect MF2 and disconnect MF1 and do the same thing.

I have redrawn the schematic here.  He only has a clamp diode on the MF2 drain, even though he should have one on both drains.  If your goal is to model what JB built then I would start with his schematic. 

He's using 1N4007s where their long reverse recovery are going to cause problems:  D3, D4, D5.  The rig in his video looks like it has a lot of undesirable stray inductance that is good for blowing up MOSFETs.  Q1 and Q2 in the schematic are damn it alls as shown.  I have reversed the emitter and collector connections so that they will do something useful.  I don't know how his board is wired up.  With Q1 and Q2 wired as in his schematic, MF1 and MF2 turn off much more slowly than as I have drawn them.  Turning M1 off really fast without protecting it with a clamp diode is a risky affair.  I recommend adding a HFA08TB60 from MF1 drain to V+ the way that D6 is connected to MF2.