My Motors got me to Tap into Radiant Energy

[sampojo]

MOSFET question

Assembling my OSHpark Monser driver v5.1 boards finally. On the MOSFET, Pin 1 is the gate, Pin 2 the drain and Pin 3 the source. What I am seeing seems a little counter intuitive, is that the "source" pin is hooked up to the board and battery ground then? Is my understanding correct? Here are the diagrams.
Schematic: (Note: R2 value is incorrect, has been changed to 330)

(This is now the corrected image, using blogspot instead of photobucket)


Package diagram


Piece schematic


Using 1 ohm on R3,8 Edit: Sorry, threw up my old express PCB schematic, not numbered the same as JS T3001 schematic. It is R7,8 on this diagram and R3,9 on the JS schematic

Any input appreciated

[Cornboy 555]

Assembling my OSHpark Monser driver v5.1 boards finally. On the MOSFET, Pin 1 is the gate, Pin 2 the drain and Pin 3 the source. What I am seeing seems a little counter intuitive, is that the "source" pin is hooked up to the board and battery ground then? Is my understanding correct? Here are the diagrams.
Schematic: (Note: R2 value is incorrect, has been changed to 330)


Package diagram


Piece schematic


Using 1 ohm on R3,8

Any input appreciated

Hey Joey, that is correct, source to battery negative, drain to - end of motor coils.

You are simply using these boards as an on/off switch on the low side, or negative side, completing the circuit.

Great to see you building these now.

Regards Friend, Cornboy.

[sampojo]

PKE250CA transil diode problem on Monster driver

My mouser part from Fairchild does not have a color band on the part to denote the cathode. The datasheet diagram says its supposed to. Can't just hook up a multimeter to see which way the current goes on these. Its says bidirectional. Does that mean it doesn't matter which way it goes?

Any body know a way to tell which side is the cathode on these?

RE post on MOSFETs, thanks cornboy! and thx! Very informative.

[sampojo]

Ground heatsinks for MOSFETs?

Should the heats sinks for the MOSFETs on Monster driver be grounded to board ground?

[iankoglin]

My mouser part from Fairchild does not have a color band on the part to denote the cathode. The datasheet diagram says its supposed to. Can't just hook up a multimeter to see which way the current goes on these. Its says bidirectional. Does that mean it doesn't matter which way it goes?

Any body know a way to tell which side is the cathode on these?

RE post on MOSFETs, thanks cornboy! and thx! Very informative.

G'day Sampojo
Bidirectional means just that you do not need to worry about polarity
With regard to the diodes that are polarized you will notice that they have a stripe around the circumference one end and if they come taped together the tape on this leg is red colour this is the cathode end the striped end


The back of the Mosfets is also connected to the centre pin the Drain which when connected to the heat sink, and this is connected to the negative of the Motor
I hope this helps

[sampojo]

thanks Kogs! conductive grease anyone?

G'day Sampojo
Bidirectional means just that you do not need to worry about polarity
With regard to the diodes that are polarized you will notice that they have a stripe around the circumference one end and if they come taped together the tape on this leg is red colour this is the cathode end the striped end


The back of the Mosfets is also connected to the centre pin the Drain which when connected to the heat sink, and this is connected to the negative of the battery

I hope this helps

Kogs, thanks a million! so cool to have a show-stopper problem when you go to sleep at night and have blokes on the other side of the world answer the question for you when you wake up in the AM!

Heres another worry wort problem, can't find my electronic heat conductive grease anywhere but would like to use it on the heat sink, but am concerned it may affect electronic conductivity on the ground connection of the heat sink. Better off grounding it independently then?

[Ufopolitics]

Drain To Negative of Battery?!

The back of the Mosfets is also connected to the centre pin the Drain which when connected to the heat sink, and this is connected to the negative of the battery

Hello my Dear Friend Kogs,

I believe the above statement tends to confusion...or am I wrong?

The Drain of the MOSFET should go to the Negative Input of Motor, and Not to the Negative of Battery...am I right?

Negative from Battery should go to Source of the FET.


Kind Regards


Ufopolitics

[Ufopolitics]

If...

Kogs, thanks a million! so cool to have a show-stopper problem when you go to sleep at night and have blokes on the other side of the world answer the question for you when you wake up in the AM!

Heres another worry wort problem, can't find my electronic heat conductive grease anywhere but would like to use it on the heat sink, but am concerned it may affect electronic conductivity on the ground connection of the heat sink. Better off grounding it independently then?

Hello Sam,

If the Heat Sink is supposed to be attached to Ground, and Ground goes to Battery Negative...Then you need to Isolate the Heat Sink from the Drain Contact through the Mica/Bakelite transparent sheets as also a washer/nut that is made of heat resistive plastic for the bolt/nut not to make contact with FET's Drain Plate...Only then you could use the Heat Grease based on White Silicon Compound which is not conductive electrically, only transfers heat.

That is my opinion, however, I have to check again the Monster Driver Diagrams

Regards Sam

Ufopolitics

[iankoglin]

G'day Sampojo
Bidirectional means just that you do not need to worry about polarity
With regard to the diodes that are polarized you will notice that they have a stripe around the circumference one end and if they come taped together the tape on this leg is red colour this is the cathode end the striped end


The back of the Mosfets is also connected to the centre pin the Drain which when connected to the heat sink, and this is connected to the negative of the Motor
I hope this helps

G'day UFO, Sampojo and all others
I wrote the above in a hurry and did not proof read it
UFO I am glad you noticed my error and I have corrected the above post

So as to stop any confusion I will delete this Post in a few Days

Kindest Regards

Kogs has never ever made even one mistake Just 100's of errors and still going

[iankoglin]

Hello Sam,

If the Heat Sink is supposed to be attached to Ground, and Ground goes to Battery Negative...Then you need to Isolate the Heat Sink from the Drain Contact through the Mica/Bakelite transparent sheets as also a washer/nut that is made of heat resistive plastic for the bolt/nut not to make contact with FET's Drain Plate...Only then you could use the Heat Grease based on White Silicon Compound which is not conductive electrically, only transfers heat.

That is my opinion, however, I have to check again the Monster Driver Diagrams

Regards Sam

Ufopolitics

G'day UFO and Sampojo
I corrected my post above

The back of the Mosfets is also connected to the centre pin the Drain which when connected to the heat sink, and this is connected to the negative of the Motor

Kindest Regards

Kogs a bit

[iankoglin]

Hello my Dear Friend Kogs,

I believe the above statement tends to confusion...or am I wrong?

The Drain of the MOSFET should go to the Negative Input of Motor, and Not to the Negative of Battery...am I right?

Negative from Battery should go to Source of the FET.


Kind Regards


Ufopolitics

G'day UFO
You are Right The back of the Mosfets is also connected to the centre pin the Drain which when connected to the heat sink, and this is connected to the negative of the Motor


Thanks for picking up my error I should proof read before pushing the submit button

Thanks my friend

[sampojo]

Heat sink ology

Hello Sam,

If the Heat Sink is supposed to be attached to Ground, and Ground goes to Battery Negative...Then you need to Isolate the Heat Sink from the Drain Contact through the Mica/Bakelite transparent sheets as also a washer/nut that is made of heat resistive plastic for the bolt/nut not to make contact with FET's Drain Plate...Only then you could use the Heat Grease based on White Silicon Compound which is not conductive electrically, only transfers heat.

That is my opinion, however, I have to check again the Monster Driver Diagrams

Regards Sam

Ufopolitics

hmm... So yeah the center pin goes to the drain and to the heat sink and to the negative on the motor, not battery ground. I guess grounding means grounding to battery ground and would be optimal. So mica insulators would be good. Got some pads from the salvaged heat sinks that must do just this job! only 2 though, good for only 1 board, but I at least know what to look for now.

I am tempted to leave them floating and ungrounded but I bet that's a bad idea. Or even attached directly to Drain without an insulator. Again probably a bad idea. I wonder what Dana did?

[sampojo]

Adding in the heavy wires on the MOSFETs

looking at using 12 or 14ga solid house wires on the light blue connections here...



I am supposing I should use 12 rather than 14, but I know it will take a lot more heat to solder, worrying about the components. Guess I can put some more heat sinking action on it like a small damp cloth...

Would 12ga be enough for an Imperial style operation taking 12-18A?

[iankoglin]

looking at using 12 or 14ga solid house wires on the light blue connections here...



I am supposing I should use 12 rather than 14, but I know it will take a lot more heat to solder, worrying about the components. Guess I can put some more heat sinking action on it like a small damp cloth...

Would 12ga be enough for an Imperial style operation taking 12-18A?

G'day Sam

Please do not use insulation pads as you can connect this way better



The cables I am using are Jaycar 12 Gauge OTC High current Power current
it has more very fine wires for Solar and DC operations solder the 12G to the ground as I have shown the solder is about 2mm thick do this before any other components




Firstly before inserting any components solder a heavy layer onto the pads where the bolts go through the pads probably 2mm thick then solder some 12G from where the source pins come out.
Use 3mm diam. countersink headed bolts then countersink for the bolt heads and use Heat sink paste when fitting the c/s bolts and use a washer and nut and tighten hard when this is done solder the other components in and when you gave soldered them you can cut off the centre pin the drain pin from the Mosfet as you are connecting through the back into the heat sinks the heat sinks 2 of them are fitted with heat sink paste on both sides of the Mosfets and bolted with 2 - 3mm screws drilled and tapped to secure them together and press them against the Mosfets and there is a bolt that goes between the Mosfets countersunk in one and secured using heat sink paste and the nuts tightened securely

The Heat sink paste is necessary anywhere there is a connection to the heat sink as this makes a proper electrical connection

You notice the 12G going from the Power out to the Heat sink you need to bend this first and measure/determine where the solder cable connector goes band bend into shape before soldering as the soldering makes this wire stiff



Any questions please ask

Kogs just trying to be helpful

[sampojo]

Kogs, most helpful indeed

Looks very well engineered! So you use the heatsink as the best connection point. I already have the center pin in place, no harm I suppose. putting some heatsink SILVER compound on order! I suppose I could beef up that connection a little too. Going with some stranded wire and filling up those pads with solder!

thanks Kogs