Title: birthday gifts to myself
Post by: sqkybeaver on December 23, 2011, 09:53:11 pm
Post by: sqkybeaver on December 23, 2011, 09:53:11 pm
here is a quick snap
[attachment=0]
[attachment=1]the thing works perfectly, up to 2M, no noticeable distortion, counter is right on with the scope.
i'll tear it apart soon ;)
[attachment=0]
[attachment=1]the thing works perfectly, up to 2M, no noticeable distortion, counter is right on with the scope.
i'll tear it apart soon ;)
Title: Re: birthday gifts to myself
Post by: sqkybeaver on December 23, 2011, 11:12:19 pm
Post by: sqkybeaver on December 23, 2011, 11:12:19 pm
this is a GW GFG-8016G, i am really impressed with this purchase. this was bought from a seller on eBay that employs and supports people with developmental challenges, a win-win in my book.
feature short list
0.1-2MHz square, triangle, sine, ttl/cmos outputs
10MHz internal/external counter
vcf input
the inside
[attachment=2]
close up of the counter ic http://http://www.datasheetcatalog.com/datasheets_pdf/I/C/M/7/ICM7216DIPI.shtml
it is clocked by a 10MHz xtal.
[attachment=1]
changing mains power is trivial, a single jumper wire has to be moved.
[attachment=0]
other ic inclide:
ua741
lm308
ca3046
7805
feature short list
0.1-2MHz square, triangle, sine, ttl/cmos outputs
10MHz internal/external counter
vcf input
the inside
[attachment=2]
close up of the counter ic http://http://www.datasheetcatalog.com/datasheets_pdf/I/C/M/7/ICM7216DIPI.shtml
it is clocked by a 10MHz xtal.
[attachment=1]
changing mains power is trivial, a single jumper wire has to be moved.
[attachment=0]
other ic inclide:
ua741
lm308
ca3046
7805
Title: Re: birthday gifts to myself
Post by: Rubu on December 24, 2011, 01:19:52 am
Post by: Rubu on December 24, 2011, 01:19:52 am
Lookin' good, gotta love your own birthday presents.
I've seen those weird angled traces before, always wondered why you would do that, seems to me it would be more trouble getting them like this than the 'normal' way, any idea? is it really that tight down there?
I've seen those weird angled traces before, always wondered why you would do that, seems to me it would be more trouble getting them like this than the 'normal' way, any idea? is it really that tight down there?
Title: Re: birthday gifts to myself
Post by: sqkybeaver on December 24, 2011, 02:05:31 am
Post by: sqkybeaver on December 24, 2011, 02:05:31 am
there is plenty of room for the traces, my best guess was it was easier than the 45 only method, they are only for the 7seg display.
not that it would be a speed problem i think this is a 20+ year old piece of equipment. i see it a lot with older electronics.
the only reason i opened it was to post some pics.
not that it would be a speed problem i think this is a 20+ year old piece of equipment. i see it a lot with older electronics.
the only reason i opened it was to post some pics.
Title: Re: birthday gifts to myself
Post by: hardcore on December 24, 2011, 06:25:54 am
Post by: hardcore on December 24, 2011, 06:25:54 am
More likely the original PCB was meant for a different case support system, then in production they had to 'hand tape' a change to get round the support pillar clearance in the final PCB fab stage.
It is common to see this sort of fix ESP. on old equipment when cad/cam was still in its younger days
It is common to see this sort of fix ESP. on old equipment when cad/cam was still in its younger days
Title: Re: birthday gifts to myself
Post by: sqkybeaver on December 24, 2011, 06:30:12 am
Post by: sqkybeaver on December 24, 2011, 06:30:12 am
the black posts came out and there is more than enough space for traces, there are odd angles and funny traces all over the board. i can't say for sure if it was or wasn't a fix.
in all, given the age, i think it is a decent pcb.
in all, given the age, i think it is a decent pcb.
Title: Re: birthday gifts to myself
Post by: bearmos on December 25, 2011, 03:02:08 am
Post by: bearmos on December 25, 2011, 03:02:08 am
The older PCB's were literally taped by hand, so the arbitrary angles were quite common since it was done manually. Also, older ECAD software wasn't quite as picky about keeping angles on 45's as it is now. . . just guesses though. . .
Title: Re: birthday gifts to myself
Post by: sqkybeaver on December 25, 2011, 03:51:53 am
Post by: sqkybeaver on December 25, 2011, 03:51:53 am
[quote author="bearmos"]The older PCB's were literally taped by hand, so the arbitrary angles were quite common since it was done manually. Also, older ECAD software wasn't quite as picky about keeping angles on 45's as it is now. . . just guesses though. . .[/quote]
i remember playing with orcad for dos when i was a kid, today it would thought of as a freshman programming class project.
i remember playing with orcad for dos when i was a kid, today it would thought of as a freshman programming class project.
Title: Re: birthday gifts to myself
Post by: arhi on December 25, 2011, 04:11:11 am
Post by: arhi on December 25, 2011, 04:11:11 am
[quote author="bearmos"]Also, older ECAD software wasn't quite as picky about keeping angles on 45's as it is now.[/quote]
That is kinda weird, p-cad, or-cad .. they all by default allowed any angle, p-cad even allowed those curved traces, i don't even remember if it had the option to lock the traces to 45degrees ... Is there actually a reason for the 45degrees most cad tools today have by default?
That is kinda weird, p-cad, or-cad .. they all by default allowed any angle, p-cad even allowed those curved traces, i don't even remember if it had the option to lock the traces to 45degrees ... Is there actually a reason for the 45degrees most cad tools today have by default?
Title: Re: birthday gifts to myself
Post by: sqkybeaver on December 25, 2011, 05:13:11 am
Post by: sqkybeaver on December 25, 2011, 05:13:11 am
[quote author="arhi"]Is there actually a reason for the 45degrees most cad tools today have by default?[/quote]
i have spoken to someone in a large pcb house in the past, for the most part 45 degrees is an optimum for small traces, the methods used for the resist don't work as well at 90. they can be lifted when cleaning of the resist or broken.
i think the uniform angles play to fill a natural human need for symmetry.
i have spoken to someone in a large pcb house in the past, for the most part 45 degrees is an optimum for small traces, the methods used for the resist don't work as well at 90. they can be lifted when cleaning of the resist or broken.
i think the uniform angles play to fill a natural human need for symmetry.
Title: Re: birthday gifts to myself
Post by: arhi on December 25, 2011, 05:32:56 am
Post by: arhi on December 25, 2011, 05:32:56 am
so the manufacturing is easier, they look prettier ... but electrically - it's irrelevant :D
Title: Re: birthday gifts to myself
Post by: sqkybeaver on December 25, 2011, 07:02:39 am
Post by: sqkybeaver on December 25, 2011, 07:02:39 am
[quote author="arhi"]so the manufacturing is easier, they look prettier ... but electrically - it's irrelevant :D[/quote]
untill you get to high speeds!
untill you get to high speeds!
Title: Re: birthday gifts to myself
Post by: tayken on December 26, 2011, 12:21:45 am
Post by: tayken on December 26, 2011, 12:21:45 am
[quote author="sqkybeaver"][quote author="arhi"]so the manufacturing is easier, they look prettier ... but electrically - it's irrelevant :D[/quote]
untill you get to high speeds![/quote]
I guess there are some RF guys in the forum who can explain this better than me but here it goes: With 90 degree bends, you kinda create an antenna, the corner, as you change the width of the trace. Also there is the possibility of over etching at the inner corner because acid might get trapped.
untill you get to high speeds![/quote]
I guess there are some RF guys in the forum who can explain this better than me but here it goes: With 90 degree bends, you kinda create an antenna, the corner, as you change the width of the trace. Also there is the possibility of over etching at the inner corner because acid might get trapped.
Title: Re: birthday gifts to myself
Post by: arhi on December 26, 2011, 12:53:22 am
Post by: arhi on December 26, 2011, 12:53:22 am
I seen bunch of 50MHz stuff with 90 degrees turn on the pcb done by HP so I'd assume "high speeds" start to count at 3 digits .. since I rarely run peripherals over 50HMz looks like I have nothing to worry about :D
Title: Re: birthday gifts to myself
Post by: erdabyz on December 27, 2011, 12:33:59 am
Post by: erdabyz on December 27, 2011, 12:33:59 am
[quote author="arhi"]I seen bunch of 50MHz stuff with 90 degrees turn on the pcb done by HP so I'd assume "high speeds" start to count at 3 digits .. since I rarely run peripherals over 50HMz looks like I have nothing to worry about :D[/quote]
Sure, the signals might have a frequency of 50Mhz, but what about the edges?
People tend not to care about them, and this is why ringing and overshoots occur if there's improper layout.
The thing about 90 degree angles is that they create a sharp discontinuity in the characteristic impedance of the trace, and that means some local impedance mismatch, which leads to reflections and things like those. However you can see (and it's pretty common and the way to go for some designs) 90 degree bendings in RF layouts, but they are optimally chamfered to avoid impedance mismatches. Also, depending on the frequency the optimal way to make turns varies. For some cases circular turns are the way to go, for others you use chamfered 90degree turns, and for some you use 45 degree (or some other angle) turns.
Sure, the signals might have a frequency of 50Mhz, but what about the edges?
People tend not to care about them, and this is why ringing and overshoots occur if there's improper layout.
The thing about 90 degree angles is that they create a sharp discontinuity in the characteristic impedance of the trace, and that means some local impedance mismatch, which leads to reflections and things like those. However you can see (and it's pretty common and the way to go for some designs) 90 degree bendings in RF layouts, but they are optimally chamfered to avoid impedance mismatches. Also, depending on the frequency the optimal way to make turns varies. For some cases circular turns are the way to go, for others you use chamfered 90degree turns, and for some you use 45 degree (or some other angle) turns.
Title: Re: birthday gifts to myself
Post by: hak8or on December 28, 2011, 07:04:28 am
Post by: hak8or on December 28, 2011, 07:04:28 am
Oh wow, I had no idea that people were interested in seeing the guts of these guys! :P
erdabyz hit the spot. Also, to add, if you have 90 degree angles everywhere with high speed signals, not to mention the reflections, you will likely not pass the required FCC emission certifications to sell your product in the United States. Those 90 degree angles result in more emissions when doing high speed electronics. At least, that is how I understand it, I may be wrong. :P
High speed electronics is an incredibly large field, the PCB design is rather complicated and usually requires a large amount of experience to "get right".
IF you guys are interested, FPGA vendors usually make free app notes on high speed electronics, here are a few I found:
http://www.altera.com/literature/an/an315.pdf (http://www.altera.com/literature/an/an315.pdf)
http://www.ti.com/lit/an/snaa121/snaa121.pdf (http://www.ti.com/lit/an/snaa121/snaa121.pdf)
http://www.latticesemi.com/lit/docs/tec ... tn1033.pdf (http://www.latticesemi.com/lit/docs/technotes/tn1033.pdf) <-- particularly good
http://www.calyptech.com/pdf/Sig_integ.pdf (http://www.calyptech.com/pdf/Sig_integ.pdf) <-- nice and simple easy introduction
There was a particularly good free ebook but I can't seem to find it right now.
I have a function generator too, very similar to yours but less functionality. I don't think you posted how much you paid for it, care to indulge us? I will post a few pictures and whatnot of my function generator with the insides too, soon, probably by tomorrow.
erdabyz hit the spot. Also, to add, if you have 90 degree angles everywhere with high speed signals, not to mention the reflections, you will likely not pass the required FCC emission certifications to sell your product in the United States. Those 90 degree angles result in more emissions when doing high speed electronics. At least, that is how I understand it, I may be wrong. :P
High speed electronics is an incredibly large field, the PCB design is rather complicated and usually requires a large amount of experience to "get right".
IF you guys are interested, FPGA vendors usually make free app notes on high speed electronics, here are a few I found:
http://www.altera.com/literature/an/an315.pdf (http://www.altera.com/literature/an/an315.pdf)
http://www.ti.com/lit/an/snaa121/snaa121.pdf (http://www.ti.com/lit/an/snaa121/snaa121.pdf)
http://www.latticesemi.com/lit/docs/tec ... tn1033.pdf (http://www.latticesemi.com/lit/docs/technotes/tn1033.pdf) <-- particularly good
http://www.calyptech.com/pdf/Sig_integ.pdf (http://www.calyptech.com/pdf/Sig_integ.pdf) <-- nice and simple easy introduction
There was a particularly good free ebook but I can't seem to find it right now.
I have a function generator too, very similar to yours but less functionality. I don't think you posted how much you paid for it, care to indulge us? I will post a few pictures and whatnot of my function generator with the insides too, soon, probably by tomorrow.
Title: Re: birthday gifts to myself
Post by: JuKu on December 28, 2011, 09:54:18 am
Post by: JuKu on December 28, 2011, 09:54:18 am
[quote author="sqkybeaver"] i think this is a 20+ year old piece of equipment. i see it a lot with older electronics.[/quote]
Hand-taped PCB, no question. I'm old, I've done enough of those to still recognize hand taping when I see it. Nice, it's been a while since I remembered my light box. :)
About 45 vs 90: Nobody cared about angles at those times, so that discussion is irrelevant for this particular device. In general, it is a myth that sharp angles would matter in high speed designs. Sure, when your rise time is in picoseconds, the small effect* is clearly measurable, but at that range, you know what is going on and what you are doing anyway. (*: and it is still not the corner, it is the capacitance that is created when there is more copper in the corner.) You do care about trace lengths, and 45 degree routing gives you shorter tracks. Also, sharp angles are harder to etch, so your yield in manufacturing is much better without too many 90 angles, especially if the design is tight and you are working close to the process limits. (And last, 45 degrees look nicer.)
Hand-taped PCB, no question. I'm old, I've done enough of those to still recognize hand taping when I see it. Nice, it's been a while since I remembered my light box. :)
About 45 vs 90: Nobody cared about angles at those times, so that discussion is irrelevant for this particular device. In general, it is a myth that sharp angles would matter in high speed designs. Sure, when your rise time is in picoseconds, the small effect* is clearly measurable, but at that range, you know what is going on and what you are doing anyway. (*: and it is still not the corner, it is the capacitance that is created when there is more copper in the corner.) You do care about trace lengths, and 45 degree routing gives you shorter tracks. Also, sharp angles are harder to etch, so your yield in manufacturing is much better without too many 90 angles, especially if the design is tight and you are working close to the process limits. (And last, 45 degrees look nicer.)
Title: Re: birthday gifts to myself
Post by: erica1234 on December 30, 2017, 10:40:37 am
Post by: erica1234 on December 30, 2017, 10:40:37 am
Well it's that time of year again..i've just been kind of Reminiscing about my favorite gifts as kid i would have to say one of the best i ever had was (The Ghostbusters Firehouse) & (Talkboy Tape Recorder) from Home Alone 2...god i got in so much trouble with that thing,but for it's time it was an amazing gift.