Lords of the Ring

[Bruce_TPU]

@ GK
Well said!  Well spoken!  I feared some had forgotten that SM was specific about three frequencies.  One is fun, two is danger, three is power!    And folks are excited about just one frequency!  LOL

@everyone
As you all know by now, I still believe there will be a ryme or reason to the frequencies chosen. 
1=resonant
2=harmonic
3=intermodulation    This is my thoughts, and we will see if they proof out.  Either way, keep it in your minds to give you something to experiment with.  Jason also has some very interesting ideas about the three frequencies and resonance.

Cheers,
Bruce

[weri812]

hi gk

have you fired up your big mac yet ?
if yes  how did it work 

@bruce

question?

by tuneing the third freq  up and down  would it incress pow er and decress power ?

wer

[giantkiller]

Here is the mechanical start of my driver board. Only three drivers are needed but I want to make it with four fets to include a switchable h-bridge configuration for future options. Gonna try anyway. Not mandatory.

Two 556s, one max621, four irf840s. All 12v operation. Blue terminal blocks for all connections. Fets in little sockets. And one 12v fan.

I have gone a little slow this session. Wanted to make sure of a precise,semi tight fit. Soldering next session. There is a 7805 on board in case i need one.

--giantkiller.

[Thedane]

I have gone a little slow this session. Wanted to make sure of a precise,semi tight fit. Soldering next session. There is a 7805 on board in case i need one.

--giantkiller.

Hi giantkiller

I've been designing a mosfet driver pcb for testing purposes.
I'm using the MC33151 driver chip (We use them at work  )

In the datasheet: http://www.chipcatalog.com/Datasheet/3BE1EB3D09E88BB88DC3414BAA767550.htm

it says:
Do not attempt to construct the driver circuit on
wire?wrap or plug?in prototype boards. When driving
large capacitive loads, the printed circuit board must contain
a low inductance ground plane to minimize the voltage spikes
induced by the high ground ripple currents. All high current
loops should be kept as short as possible using heavy copper
runs to provide a low impedance high frequency path. For
optimum drive performance, it is recommended that the
initial circuit design contains dual power supply bypass
capacitors connected with short leads as close to the VCC pin
and ground as the layout will permit. Suggested capacitors are
a low inductance 0.1 mF ceramic in parallel with a 4.7 mF
tantalum. Additional bypass capacitors may be required
depending upon Drive Output loading and circuit layout.
Proper printed circuit board layout is extremely
critical and cannot be over emphasized.

I would think this goes for the max621 as well, though it says nothing about it in its datasheet.

Good luck on the project 
Egon

[eldarion]

I have gone a little slow this session. Wanted to make sure of a precise,semi tight fit. Soldering next session. There is a 7805 on board in case i need one.

--giantkiller.

Hi giantkiller

I've been designing a mosfet driver pcb for testing purposes.
I'm using the MC33151 driver chip (We use them at work  )

In the datasheet: http://www.chipcatalog.com/Datasheet/3BE1EB3D09E88BB88DC3414BAA767550.htm

it says:
Do not attempt to construct the driver circuit on
wire?wrap or plug?in prototype boards. When driving
large capacitive loads, the printed circuit board must contain
a low inductance ground plane to minimize the voltage spikes
induced by the high ground ripple currents. All high current
loops should be kept as short as possible using heavy copper
runs to provide a low impedance high frequency path. For
optimum drive performance, it is recommended that the
initial circuit design contains dual power supply bypass
capacitors connected with short leads as close to the VCC pin
and ground as the layout will permit. Suggested capacitors are
a low inductance 0.1 mF ceramic in parallel with a 4.7 mF
tantalum. Additional bypass capacitors may be required
depending upon Drive Output loading and circuit layout.
Proper printed circuit board layout is extremely
critical and cannot be over emphasized.

I would think this goes for the max621 as well, though it says nothing about it in its datasheet.

Good luck on the project 
Egon

GK,

I have been using the HIP4081AIP MOSFET driver on a scrap of perfboard for some time now with no issues.  You might want to use it; I haven't blown up a single one and the MOSFETs are driven cleanly with fast rise/fall times.

Egon is right about the max261 / ucc32321 series chips.  I tried prototyping with them and blew up my entire stock save one.  That last one I installed 5 bypass capacitors directly on the power leads, including a large electrolytic.  Trust me, it is a pain!

Hope this helps,

Eldarion