Akula0083 Light No3 - Dual TL494

[MarkE]

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

Greets JB

They have lower gate charge than the IRF3205's so that is the probable reason. 

Did you wire the two PNP transistors as shown in your schematic with the collectors connected to the MOSFET gates, or as I have drawn them with the emitters tied to the MOSFET gates and the collectors connected to the circuit common?

[JohnnBlade]

Correct, the collector goes to the gate of the mosfets.

Greets JB

They have lower gate charge than the IRF3205's so that is the probable reason. 

Did you wire the two PNP transistors as shown in your schematic with the collectors connected to the MOSFET gates, or as I have drawn them with the emitters tied to the MOSFET gates and the collectors connected to the circuit common?

[MarkE]

Correct, the collector goes to the gate of the mosfets.

Greets JB

Are you sure?  If the emitters go to the MOSFET gates, then they are emitter followers that turn the MOSFETs off much faster than the 100 Ohm and 180 Ohm gate to common resistors would by themselves.  With the emitters on the circuit common, the base voltage being always a positive value, and the transistors being PNPs, the base emitter junction never forward biases.

[JohnnBlade]

Dexor, please built the circuit and then compare with yr sims.

im saying it cause yr sims never knew how to handle real life proximity feeling that are introduced into the circuit, unless you know how to sim that

nice work though

Greets JB

I don't understand why spice does such strange things with inductors....


Threw together most of the TL494 circuit with just pulse generators as drivers for the mosfets ...


I added a huge farad cap which would be effective power used (eventually)...


L1 is the pickup inductor  (red current through this coil)
L2 higher induction driver (blue current through this coil)
L3 lower induction driver  (green current through this coil)


Purple; lower frequency driver(M1); cyan higher frequency driver (M2)


1) L1 only gets effective current after the pulses; really it should be a combination of the increasing current while the primaries are increasing...
2) current in L2 and L3 is backwards; and when I reverse L2 (picture2) It somehow kills the other coil's ability to conduct...


I don't understand if the coils are connected in the same direction... okay if I remove the inductor binding argument, they do go in the same direction... so because of mutual induction the  it ends up forcing current backwards through M1....  why M1?  that's on the higher inductor coil; would think it would have more influence on L3 than L3 has on L2....


Spice sim source

[d3x0r]

Dexor, please built the circuit and then compare with yr sims.

im saying it cause yr sims never knew how to handle real life proximity feeling that are introduced into the circuit, unless you know how to sim that

nice work though

Greets JB

Ya; I did revise my theory from the 1:3x frequency idea given the sim


---
so revised hypothesis on timing:
Low frequency driver should maybe drive near to saturation for a length of pulse...and the high frequency driver should be ... as short and rapid as possible... although lots of cycles causes lots of usage.......

although the time of high frequency pulses probably shouldn't be less than the pulse width of the low frequency driver... do not want these to collide... because they do not have an additive property.----

I found that other than specifics like frequencies that the RL circuit resembles the sim; I dunno maybe this weekend; I'm not having much luck with the 3V flashlight.... I did have about 30V of LEDs lit at about 10mA brightness on 3.4V and 0.04A... but I can't get back there