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smaller coils (and a 12MHz target)

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LAN_403

...

Wed Aug 30 2006, 03:02AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

And it wouldn't surprise me if the quality of your driver is actually BETTER than that of the $100k THz spectrometer that I was helping design (I resigned today since school starts tuesday and I still need to get my sstc and nd:yag obliterator going)...

My criteria being:
1. Ours has headers made out of 22awg wire (150 pins per unit made by yours truly)
2. Ours has bits of wirewarp wire running around through vias on the board
3. The wiring I did on ours looks ~4x as good as the rest of the wiring
4. Ours was built by a 16 year old
5. On the todo list for ours there was a note:
"get bigger fuses the 3a ones blow out

On the other hand yours:
1. Has a custom designed gdt to give foolproof gate drive
2. Has a very low inductance layout
3. Uses the inductance of the wiring to its advantage
4. Was built by a 18 year old
5. Emits at a much more reasonably 6mhz as opposed to this dangerous THz stuff (well not yet at least

)

Avalanche

Wed Aug 30 2006, 10:12AM

Registered Member #103 Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845

I'd vote for this to appear on 'featured project' on the front page

When you get first light/sound/temporal disturbance that is

ragnar

Wed Aug 30 2006, 08:43PM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

... wrote ...

1. Has a custom designed gdt to give foolproof gate drive
2. Has a very low inductance layout
3. Uses the inductance of the wiring to its advantage
4. Was built by a 18 year old
5. Emits at a much more reasonably 6mhz as opposed to this dangerous THz stuff (well not yet at least

)

I think you're giving me more credit than I deserve... =P

...

Wed Aug 30 2006, 09:35PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

I need to coax some spark pix, some artwork, and some boards out of you

Steve Conner

Wed Aug 30 2006, 10:43PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

... I work for a company that makes laser and optical gear. I showed my boss your post and he says he'll never buy an Emcore THz spectrometer now, and tell all his friends not to buy one either

Seriously, I guess it's a prototype, and prototypes always look a bit scary. Our prototype laser drivers are a mass of breadboard, superglue and wire-wrap wires (that always fall off at random without anyone noticing and cause huge grief) but by the time they make it to production they are nice and neat.

Blackplasma let's see that thing going! Or catching fire or whatever. To stop the FCC (or whatever the equivalent is in aus) kicking your butt it's usual to use 13.56 or 27.12MHz, these are the "ISM bands" designated for industrial RF heating gear and such like.

I'd also vote for featured project.

...

Wed Aug 30 2006, 11:24PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

They already sold these 5

They should neaten up the wiring a little and they ordered the correct headers for the rest of the units but...
I should poin out the only time I heard the circuit guy laugh during the 2 months I was working there was when I noted that "this is how I do things at home

when he told me to build him some 72pin headers out of 22awg wire and to sand down the sockets becuase the plastic was too thick on the ends for them to stack end to end. hehe, for $100k you would THINK you would get something better...

BP definantly deservs front page status; just as soon as I see 4 resonators playing ac/dc

I also want to ask you that to try using graphite as a breakout point; I want to see how it holds up at 6mhz

ragnar

Sun Sept 10 2006, 06:07AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

Testing the limits of UCCs here... with no load, their outputs start to die to nothing at ~18MHz.

Here they are driving two IRF510s (resonant circuit through GDT) at 17.2MHz. The IRF510s will form a halfbridge, for driving the gate of an IRFP450 or similar, through another ferrite transformer.

Marko

Sun Sept 10 2006, 01:17PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

I see you are soon going to set a resonance with subspace fabric

With a resonant drive practically only limt are delay times of UCC chip.

As school started again I'l also be back soon to my class E stuff..

ragnar

Sun Sept 10 2006, 01:31PM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

Actually, I point out that the frequency limitation (even with zero load) of the UCC chip is 18MHz.

Also worth noting that the UCC37322 and UCC37321 chips give different waveforms... presumably because the buffer/inverter stage incorporate different delay times... so the output waveforms are asymmetrical and there is probably cross-conduction. I'll see if this is worth solving with a 74HC inverter or something... or not =-P

Practically speaking, you wouldn't want to be driving a load much bigger than maybe ~500pF total at 17MHz.. the UCCs just can't handle it, they latch up.

To make the gate capacitance a little more predictable, I partly swamp it with a 100pF ceramic capacitor on each IRF510, bringing the total apparent gate capacitance to 235pF each. I'm using an 11:2 ferrite to couple the UCCs to the IRF510, and even then it's a struggle, so I have put little heatsinks on the plastic packages... they seem to keep them just cool enough to stop the latching. =-P

Marko

Sun Sept 10 2006, 02:01PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Maybe you could just put away the UCC's and use simple totem pole driving small class E preamplifier ala richie burnett.

Or maybe dual DEIC420driver for squarewave at 20 Mhz :) Since you are rich it won't be a big problem for you..

Much bigger problem I see is that IRFP450 won't be capable of moving his ass at 18Mhz respectably.

Maybe you could try paralelling smaller mosfets to gain some speed...

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