Homebrew 3 Channel Pure SIN Generator ( 0 ... 60MHz )

[Yucca]

@Sparks,

Opto isolation sounds like a good idea if I can get something fast enough. I will build this pure sin box with no protection but I will only use it to drive another box or board that then will have the finals in it, fast schmitt and FETs for squares (with a little PWM) and some beefier amp stage for sin. This box will have some isolation in it and also it power input line will have non inductive shunt for scoping total drive power. For COP calculation I will ignore the draw of the sin gennies and micro and just look at the final drive stages draw.

@GK

I will be taking all the clocks off the 3 modules and making a small daughter card with one clock and 3 same length coax runs to feed each module. One clock module should handle the fanout and be able to drive 3 DDS chips OK.

The DDS chips are 5bit programmable for phase (thru the serial bus), so 32 sector resolution. i.e. I can set each oscillators phase to these degrees:

0 ... 11.25 ... 22.5 ... etc. all the way up to 348.75 and back to 0

So I should be able to set up a reasonable 3 phase signal at 0, 123.75 & 236.25 degrees at any frequency, might be interesting to try and get stuff spinning in the double digit MHz range, coil placements could perhaps be moved slightly to compensate for the imperfect 3phase angles.

2 phase (for quadrature) will be spot on at 0 and 90 degrees.

[Yucca]

Just ordered one of these:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390098652853

Now I have the case dimensions I will start to plan and lay out the vero boards. It will be a tight squeeze so I'll wait for the case to arrive before I commit to soldering anything.

After thought I want to firewall the case with RF shield and have the oscillators on one side and the micro on the other. All digital and power lines will pass through feedthrough caps on the firewall.

Each RF module will also have its own shield to minimise crosstalk, these shields will be made from stiff carboard and wide aluminium tape. RG174 coax will be used to bring the final signals to the front panel.

[giantkiller]

@Yucca,
And that will equate to a full metal jacket. 

[innovation_station]

great work yucca ...

you have yourself a verry nice control unit ...

i was lucky enough to get many cases for for building tpu controllers inside of...  they are solid alum forged ... they were originally designed for rf applacations ...

i will soon gut a unit and start building

but i want a tube unit ... 

aswell i have aquired a few more tube amps ... 

agin great work yucca ...

ist!

[Yucca]

great work yucca ...

you have yourself a verry nice control unit ...

i was lucky enough to get many cases for for building tpu controllers inside of...  they are solid alum forged ... they were originally designed for rf applacations ...

i will soon gut a unit and start building

but i want a tube unit ... 

aswell i have aquired a few more tube amps ... 

agin great work yucca ...

ist!

Cheers ist, forged alu cases are real nice and dont come cheap, you're sitting on a few dollars just for the ALU scrap price there!

Tube controller, sounds like a very interesting build. be sure to hook us up with more info as it progresses.