Convenient source of FR4 core for protos

I think i have some 24 mil Megtron, 18x24 sheets double sided.

I've seen better. Also, they need to learn CSS. :)

Back in the day, I had purchased a flat rate box full of random clad, about 10lbs worth, for $50 (inc. shipping). 0.031, 0.04 and 0.062" thicknesses, 0.5, 1 and 2 oz. foil, double sided. Still chewing through it, and that's after making a few projects like this:

Doesn't seem to be such an offer on eBay anymore, or at least not easily found (the Chinese sellers seem to crowd out any such sales..). Among the Chinese ones, it seems like $0.03/in^2 is a good deal, which I seem to recall being typical for "nice" cuts.

Tim

--
Seven Transistor Labs 
Electrical Engineering Consultation 
Website: http://seventransistorlabs.com 

"Simon S Aysdie"  wrote in message  
news:fb1fb99f-a83b-423a-af88-c4e7515caf62@googlegroups.com... 
> More thicknesses than you'll find at Mouser or Digikey.  I needed  
> something pretty thin. 
> 
> And so easy/quick to cart and check out. 
> 
> http://www.ebay.com/itm/FR4-Copper-Clad-Laminate-PCB-Printed-Circuit-Board-Material-FREE-SHIPPING-USA-/120802756087

Cute. Projects like that are fun. While I was working in satcom as a nipper, I built a quartz-synthesized FM receiver that looked like that, except not as neat as yours. The synthesizer was all old-school, with BCD to 7-segment decoders to display the RF frequency and cascaded

74LS161 counters to set the LO, with the IF offset subtracted from the preload.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

Pass it along!

Well, thicknesses on that order seem to be easy to find. I was looking for something in the 10 to 16 mil range. I ended up trying the 12 mil this fi rst time. It should be here shortly.

Nice. I already have the thicker stuff. I'll actually be stacking thick a nd thin. (I think I see you did some of that.) Some SMD components will sit on top of little "pad cuts" of thin stuff. Others will sit on a "tilt" fr om the thicker substrate ground plane up to the top copper of the little pa d cuts.

e

Yeah, there's a lot to be said for "ugly" construction directly on single- or double-sided stock. I grab sheets of this sort of stock at any hamfest flea-market I attend. Got a couple of good-sized cutoffs of Rogers high-frequency board for $5 each a while ago... don't have a need for anything this exotic at the moment but it's nice to have it available for whenever.

I've built a few small projects this way - straight-up "ugly" on bare board, "Manhattan" (with discs or squares of board chopped up, and glued to bare board to serve as pads), and "pad cutter" (making isolated pads with a core drill).

After doing a small charge-sensitive preamp the latter way, and disliking the dust which comes from milling out the pads, I sat down with KiCAD and some Perl scripting code and used 'em to gin up layouts for a couple of sizes of "rectangular arrays of isolated circular pads" boards. They're sorta like what I saw sold as "Ivanboard" years ago. DirtyPCBs makes two sizes of boards for cheap (5 cm square $14/10, and 10 cm square $25/10, HASL, solder mask, silkscreen, delivered) so I made both types... they're en route from Hong Kong now. If they look good when they arrive I'll probably open-source the design and publish the Gerbers, in case anybody else wants to make a batch.

There's no law against making them beautiful.

--

John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

On the third board (the EOM Timer), there is a resistor, just under the RM SMB connector, that has one end not soldered.

I think I fixed that after I took the pic. I know that the monitor output does work!

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com