Mosfet Help

[NickLee]

I am in the VERY slow process of building a PWM.. th edesigns i have been basing mine on only have one power mosfet (75a 55v) and i am wanting to add more of these and what i am wanting to know is when i am hooking up multiple fets to the same circuit do i just design my pcb the mount in with all of the gates connected all of the drains connected and all of the sources connected? I ahve also included the schematic (which i ave no idea how to read) if it will help at all (i dont even know if it shows the FET,... but it does show the voltage regulater) oh yeah... can anybody please tell me where the heck C5 (the 4.7µF 100v) capacitor connects?!!!
THANKS FOR ANY HELP!

 

[mneary]

Why do you want to add more mosfets?

 

[bassnut]

The symbol on the bottom of C5 is 0v, or ground, all the components with this symbol are connected to 0v, it saves extra lines all over the schematic. C5 is simply a pwr supply smoothing capacitor (to handle higher frequencies than C7, which is also a pwr smoothing cap). The FET shown is 75A, as mneary says, why would you want more FETs?.

 

[Leftyretro]

R12 is going to interesting to find, not something that a radio shack has

Lefty

 

[ericgibbs]

Why do you want to add more mosfets?

I bet he is trying to split water , HHO

 

[audioguru]

I bet he is trying to split water , HHO

I think so too. His few bubbles of HHO didn't make any difference (like everybody else found) so he is trying to make more.

I notice that the circuit uses a lousy old LM324 quad opamp that can't go to the high frequency he wants.

 

[blueroomelectronics]

HHO did someone say HHO? Bah Humbug.
Scientific proof debunking the "run your car on water" scams
**broken link removed**

 

[NickLee]

Yes i am spliting water... and i am wanting more fet for more power.. i havent noticed to few bubbles it hasent been put in a car i allready have all components (including r12) on the board... the fets are going to be attatched to a different board but i need to know how i need to wire multiple fets up before i draw out the board... i want more fets for the option of more power the will be able to be swithed on and off.. Bassnut did c5 just connect to pwr and gnd?
and none of this is being made for a car... its being made just to do it...

 

[blueroomelectronics]

Doesn't work, never will. Save your money and buy a solar panel.

 

[NickLee]

I think so too. His few bubbles of HHO didn't make any difference (like everybody else found) so he is trying to make more.

I notice that the circuit uses a lousy old LM324 quad opamp that can't go to the high frequency he wants.

What would you suggest useing if the LM324 isnt good enough?

 

[ericgibbs]

What would you suggest useing if the LM324 isnt good enough?

hi,
One of your problems will be current limiting of each individual FET using that LM324 'Duty' sampling circuit.
For starters you would need the R12 for each FET.

 

[blueroomelectronics]

Ah well, I tried to help. Have you checked with www.overunity.com ?

 

[audioguru]

A lousy old LM324 has a max frequency of about 6kHz when its supply voltage is 13V.
It is different from most opamps because its inputs work at a voltage near ground.

An MC34074 is also a quad opamp that has inputs that work at a voltage near ground. But it has a max frequency of 100kHz.

 

[blueroomelectronics]

Don't you need several GHz to get the hydrogen out of water?

 

[audioguru]

Stanley Meyers used tens of kHz so this one will be the same.

 

[blueroomelectronics]

Oh yea, Mr Meyers. Well the dead tell no tales. Oh wait he was a fraud...

 

[NickLee]

A lousy old LM324 has a max frequency of about 6kHz when its supply voltage is 13V.
It is different from most opamps because its inputs work at a voltage near ground.

An MC34074 is also a quad opamp that has inputs that work at a voltage near ground. But it has a max frequency of 100kHz.

Would that work as a direct replacement of the LM324? or would the board have to be redone?

 

[audioguru]

Would that work as a direct replacement of the LM324? or would the board have to be redone?

The LM324 has poor spec's because it is low power so it is slow. The MC34074 has normal power so it is fast. They have exactly the same pin numbers. Just unplug the LM324 and plug in the MC34074.

 

[NickLee]

The LM324 has poor spec's because it is low power so it is slow. The MC34074 has normal power so it is fast. They have exactly the same pin numbers. Just unplug the LM324 and plug in the MC34074.

thanks for the advice... you wouldent happen to know how to wire the multiple fets would you... i think i would just hook the multiple gates drains and sources to the same place that the one would normally connect but i dunno for sure

 

[Mikebits]

You could always use a higher power fet, but take a look at these App notes.

https://www.electro-tech-online.com/custompdfs/2008/12/avalanche_sae04.pdf

https://www.electro-tech-online.com/custompdfs/2008/12/an-941.pdf