OT: ExpressPCB (cross-post from volts-nuts)
http://dirtypcbs.com/store/pcbs
Very happy with them.
Dave
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf
Of Dr. David Kirkby (Kirkby Microwave Ltd)
Sent: Friday, December 09, 2016 12:07
To: Discussion of precise time and frequency measurement;
Discussion of precise voltage measurement
Subject: Re: [time-nuts] OT: ExpressPCB (cross-post from volts-nuts)
On 9 December 2016 at 19:58, BIll Ezell wje@quackers.net wrote:
Sorry if I'm behind the times, just did a new project that
required a pcb,
and ExpressPCB is my go-to vendor for one-off boards. I
just noticed they
now provide the low-cost boards (fixed size, 3x5, quantity
- that I've
always ordered with silk screen and solder mask for $71. I
got my latest
boards that way and they're beautiful. No relationship to
them, just a happy
customer. You can still get the barebones boards for $51.
You also lock yourself into one vendor. There's other free software,
like Kicad, where you can export files that many PCB manufacturers
use. So you avoid vendor lock-in.
https://en.wikipedia.org/wiki/Vendor_lock-in
If the company goes belly up, where are you going to get any more
boards made, without starting from scratch?
Anyway, it is a bit off topic.
Dave
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Lowest price I've found is BasicPCB.com They charge $3 per square
inch for 2 layers with mask and legend. Minimum is three boards of 1
square inch. So you actually can place a $9 order with them. They
are a USA based company.
They accept standard Gerber files. This is very impotent as a few
others like PCBexpress make you use their proprietary layout software
and then you are locked into that company for production runs too.
You need a workflow that uses Gerber files.
There is a free tool (Robot Room Copper Connection) that will take EcpressPCB files and spit Gerber files. It is actually a full fledged PCB design software that seems to be significantly more capable than the ExpressPCB software even though I have not used it as such.
Alternately you can send some money to ExpressPCB and they send you the Gerber, but only if you have actually bought the boards from them. So I usually get my first 3 prototypes from ExpressPCB and if I need to make small changes and feel comfortable buying production quantities without a second set of prototypes, I make the mods and get the Gerber from CC.
On December 9, 2016 2:07:10 PM CST, "Dr. David Kirkby (Kirkby Microwave Ltd)" drkirkby@kirkbymicrowave.co.uk wrote:
On 9 December 2016 at 19:58, BIll Ezell wje@quackers.net wrote:
Sorry if I'm behind the times, just did a new project that required a
pcb,
and ExpressPCB is my go-to vendor for one-off boards. I just noticed
they
now provide the low-cost boards (fixed size, 3x5, quantity 3) that
I've
always ordered with silk screen and solder mask for $71. I got my
latest
boards that way and they're beautiful. No relationship to them, just
a happy
customer. You can still get the barebones boards for $51.
You also lock yourself into one vendor. There's other free software,
like Kicad, where you can export files that many PCB manufacturers
use. So you avoid vendor lock-in.
https://en.wikipedia.org/wiki/Vendor_lock-in
If the company goes belly up, where are you going to get any more
boards made, without starting from scratch?
Anyway, it is a bit off topic.
Dave
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To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
--
Sent from my Moto-X wireless tracker while I do other things.
Lowest price I've found is BasicPCB.com They charge $3 per square
inch for 2 layers with mask and legend. Minimum is three boards of 1
square inch. So you actually can place a $9 order with them. They
are a USA based company.
They accept standard Gerber files. This is very imported as a few
others like PCBexpress make you use their proprietary layout software
and then you are locked into that company for production runs too.
You need a workflow that uses Gerber files
One thing I'm doing is converting a small mill to CNC operation. I'm
doing this to make metal parst but a secondary use is that I hope to
be able to make at least simple PCBs for larger parts.
On Fri, Dec 09, 2016 at 08:25:52PM -0800, Chris Albertson wrote:
Lowest price I've found is BasicPCB.com They charge $3 per
square inch for 2 layers with mask and legend.
OSHpark charges $5 per square inch for the standard 2 layer
order (which include three boards, i.e. actually 3 square
inch or $5/3 per square inch) including mask and silk screen
on both sides, no limit to vias or general drill hits but
unfortunately no electrical check.
Minimum is three boards of 1 square inch. So you actually
can place a $9 order with them.
You can get a a lot lower with OSHpark there, I had orders
below 2 USD and they ship for free, worldwide.
They are a USA based company.
OSHpark too.
They accept standard Gerber files.
Besides Gerbers, they also process KiCad and Eagle design
files.
This is very impotent as a few others like PCBexpress make
you use their proprietary layout software and then you are
locked into that company for production runs too.
Yes, nasty.
You need a workflow that uses Gerber files.
Best,
Herbert
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Hello,
I have an SR620 that i am trying to get some more life out of. I have dedicated a raspberry pi 2 to recode data and make the files available through the network. I wrote a small c deamond that will setup the counter to make frequency measurements and save the result to a file on the flash card.
Overall it is basically working but.... on start up i have an odd behavior.
My file format is a "two column " file, column 1 is elapsed system time in seconds, and column 2 is the measurement returned by the counter. When the program starts I get 2 to 5 measurements that are wrong. A number of measurement are returned in the first second,
How I setup the counter:
// get id of counter, if it is not an sr620, exit with error;
fprintf(stream,"*RST\n"); // system reset
sleep(10);
fprintf(stream,"CLCK 1\n"); // external timebase
fprintf(stream,"AUTM 0\n"); // automatic masurment off
fprintf(stream,"MODE 3\n"); // mesure freqency
fprintf(stream,"GATE1 E1\n"); // set for 10 second gate
fprintf(stream,"SIZE 1\n"); // 1 sample per mesurment
fprintf(stream,"TERM 1, 0\n"); // 50 ohm termination for channel "A"
fprintf(stream,"LEVL 1, 0\n"); // trigger level 0.00
fprintf(stream,"TCPL 1, 1\n"); // AC coupling, channel A
sleep(4);
// pause for a bit
loop until quite {
fprintf(stream,"STRT;*WAI;XAVG?\n"); // start measurement, wait till complete,
while ((bytesread = getline(from serial port stream) != -1) { // will block until full line
if (bytesread >10) break;
}
// write data to file,
}
// close serial port
// close data file
example output:
#type=Freq
#start_date=1482003092
#f_nom=2e+7
0, 1.999999881895E+07
0, 1.999999881912E+07
0, 1.999999881757E+07
7, 1.999999881856E+07
17, 1.999999881878E+07
27, 1.999999881900E+07
37, 1.999999881877E+07
47, 1.999999881908E+07
57, 1.999999881921E+07
What do you think?
Link