Large heat sink needed

Wull yah, I got some o' them. They're 6 x 8 sheets of 1/16" aluminum! You'll have better luck getting what you need if you specify the thermal resistance to ambient you need (degrees per watt), and whether or not you'll provide forced air cooling aka a fan.

Check out some of the CPU sinks they have on the surplus market. They have a bazillion tall but very thin fins. They're not very big, but with fan cooling they have amazingly low thermal resistance to ambient.

Sounds like an interesting project.

Another project that I think would have a lot of appeal is a VFD-like device that converts singlephase to threephase, power of maybe 1.5 HP to 5HP would meet a lot of needs. RPC's do this fairly well and are cheap where there's a ready source of large 3phase motors, but power electronics are getting cheap too. It wouldn't need to be VF to be of interest. It would have a bunch of caps for energy storage but it would be silent and not take much space.

I'll check, but I just cleaned out some stuff & recycled the big ones.

Cool!

I've used TinyCAD:

*Very* basic, but that means a short learning curve. I tried a couple of others first and cut my losses after a day or so of frustration. TinyCAD has a Yahoo support group.

Bob

(...)

EAGLE!

--Winifred

My VFD design will meet those requirements. The input can be DC from batteries,

24-220Vac single phase or 3-phase from a rotary converter. I designed the VFD using standard CMOS integrated circuits and discrete components. The idea was to keep the design simple enough for a hobbyist to build with a minimum skill set in electronics along low construction cost. Reapairability was also a concern so all the IC's are socketed for easy fixes. The approximate cost of the components for the logic/driver board is $30. The IGBT's were scrounged from ebay, i am using 3 DTR units rated at 1200v 100A which cost me $25 for all 3.

The other neat thing is that with my design you get variable speed and variable torque at no extra charge.

Best Regards Tom.

Sounds great, if you could email me the pix at your convience snipped-for-privacy@cox.net along with the price you need to get i will be a happy camper.

Best Regards Tom.

If i cant find a suitable heat sink and am forced to build a heat sink thats the route i will go. Affix a bunch of BGP heatsinks on an aluminum plate and fashion a tunnel heat sink with forced air cooling. Really don't want to do that if i can avoid it.

Best Regards Tom.

I've got a couple approx 6 x 14". I'll be gone in the morning, but can email a pic in the early afternoon.

Jon

Is there someone nearby that sells / services car/camping fridges? The peltier based ones I've salvaged have nice sized ally heatsinks in the back of them. The cheaper fridges are not worth repair and get thrown in the skip rather than fixed.

I have some fancy Wakefield 3.5" wide extrusion, I suppose you could use two of them side by side. The stuff costs me $18 per foot.

Jon

Very interested in what you have done! Did you use the IR kit design, or somebody's microcontroller?

I have designed the control logic in an FPGA for a 2-phase motor on a high-speed spindle, but still have a bunch of testing to do before it would work.

Jon

Too far away to make shipping sensible, but very interested in your experience/design. At some point I may need to build a replacement for the $20

16kVA VFD setup that I'm currently abusing for my toys, preferably one where the star point isn't 175V away from the ground voltage as at present...

regards Mark Rand RTFM

Tom,

I don't have any THAT big, but I could get you a couple pieces of 3" wide aluminum heat sink.

If I remember right, it has 1/16" think fins with 1/16" spacing...the total thickness is 1/2" and the fins are 3/8" tall.

If that'll work, I could likely get two 8" long pieces for you.

How much? That's the best part...considering how much steel you gave me a few years ago, it'd be gratis.

Mike

Oh...I'll get more precise numbers on the size tomorrow.

Mike

I don't use a microcontroller. In order to keep it as simple as possible i use two CMOS chips, 6 opto isolators and 3 IR gate driver chips driving 3 GTR IGBT's. They idea is to offer an alternative to rotary phase converters, just a very basic VFD that will work reliably the first time you apply power.

When i started out on this project my thoughts were that most people with a home shop only just want to run thier 3 phase machines and make chips. They may not need or want a lot of bells and whistles that commercial VFD's offer, they just want 3 phase power. Those were the design parimeters i used to build my unit with.

I will sometime in the future design a interface that plugs into a standard PC printer port for people that want to experiment with controlling 3 phase motors via computer.

Best Regards Tom.

Thanks for the offer mike, but your heat sinks are to small for my application.

Best Regards Tom.

Tom,

Good freeware Schematic capture and PCB layout can be had here.. I've made a dozen of so PCB's using this

PCB layout dosen't produce "gerbers" but can be directly sent to ExpressPCB, and yes for 50 bucks they'll send you a "gerber".

I understand that since ExpressPCB has been "eating their lunch" that good old Advanced Circuits now offers a free schematic capture and PCB layout program but I haven't tried them

I have a 3.5 x 4 x 12 Heat sink off an old analog power supply, I has 9 fins that run the full 12 inch length and mounting for 8 (4 on each side) TO-3's

What ya got to trade?... I'm alwasy interested in 5C collets...

I'm sure you can figure out how to e-mail me...

--.- Dave

So, is this a 6-step drive that just runs 60 Hz? That really isn't a "VFD", as you can't vary the frequency without also varying the effective voltage through PWM. 2 SSI CMOS chips doesn't sound like it could do that.

Jon

I will be posting a video of the VFD in operation as soon as i have a heatsink to mount the IGBTs to. The video will show the motor speed being varied between about 125 Rpm and 1725 Rpm.

Best Regards Tom.

Nope, they're gone. Sorry.