On Friday 16 April 2004 01:50 pm, Stefan Trethan wrote:
<...>
The design was fun, I used an op amp and provided for a variable DC
offset in there. Also a logic-level output for sending slower pulses into
TTL. The board was one of those plug-in boards (44-pin edge connector)
sold for prototyping work. I've been messing with this stuff for a *long*
time and STILL haven't seen the need to make boards for stuff, unless I
was going to do a lot of some particular circuit, and it hasn't worked
out that way.
That only depends on how well your process is set up. I tended to make
circuits without prined boards in the past, but now it is not really more
time demanding to make a board, and it is really much more convenient.
I don't tend to see it that way. And making a circuit-specific board is fine
if you have a design that's nailed down, and you know it's going to work as
it is. I was fiddling with things and changing things as I went along...
also you can hardly use smd on those proto boards.
I have no intention of doing anything with that stuff if I can help it. Sure,
the old parts are reportedly getting harder to find, I hear, but I have
plenty of parts to mess with, and while some of the newer stuff may be
exceedingly nifty, I don't see a _need_ for it. I'm not after minimum size,
and feel that overall the major thrust of SMD is convenience in manufacturing
more than anything else -- manufacturing in large quantity, which I'm not
doing.
(And i can make boards cheaper than buying the proto boards)
Perhaps. I don't use all that many of them, and in fact have found some in a
box that I've had for years, and never opened.
If you are facing working with a rather unknown pcb software, making a
layout, sending it out and paying a lot, waiting weeks... i know this makes
you use protoboards. But if you are experienced with the layout software and
have a good pcb setup you just print it out,
This assumes the use of a laser printer?
fuse it,
Are you talking about toner transfer here?
peel it,
And here?
etch it,
Yeah, not time-consuming if you happen to have everything already set up to
use, and don't have to go through all of that process...
drill it,
Another time-consuming aspect of it, unless you have a CNC setup or similar
(something that's on my list to do).
ready. no more than an hour.
I suspect that it would take me considerably longer than that.
And you have the benefit that it looks really good.
That's not a particularly relevant factor for me.
I didn't see that as being useful in what I intended to be an item of
bench test equipment. For a musical instrument, yeah, but that would be
a different project then.
I want it as a test bench item. I used the frequency sweep in the past to
make quick and easy bode plots (amplitude).
Ok, I can see where that would be useful. Maybe.
Of course i can live without but if i can include it.. well..
most of the commercial generators have f sweep so it might be a good idea.
(I agree the amp. modulation is maybe less useful but i can imagine uses
if i try hard)
That would take a very fast and expensive op amp, to be sure. Why go
up that high in terms of frequency? When I get up there I usually want
some fixed frequency and will likely use one of those crystal oscillator
modules I have a pile of here.
I don't have a pile of crystals just now.
I've been salvaging / scrapping stuff for a lot of years. :-)
If it is possible without too much investment i will try to preserve the
whole frequency range. maybe i just add another direct output from the 038
with 50Ohms, you won't need high amplitude there, or dc offset.
What part would you use to do that?
Seems like a good idea to do that, and much easier if i can keep the amp.
slow.
Yes.
What are you going to use it for that you want to go all the way up to
20 MHz?
I need a generator, i have none.. all i have is a 1Hz to 5kHz generator in
a multimeter, TTL.
In a meter? First I've heard of that.
I'm on a tight budget so all is moving between homebrew and ebay....
I've also had little to spend on this sort of thing most of the time.
You see i don't need the 20Mhz now, since i obviously don't know how to
design 20Mhz circuits ;-).
But who knows what exactly the future will bring, things are definitely
going faster and faster.
Yeah, well, just because computer speeds are getting up into the UHF range
doesn't mean that I'm going to take my hobby endeavors there, I'm happy
enough to work with audio...
I'm thinking about adding a ttl out the the counter i am just programming,
i have a fast crystal in there already, a thumbwheel encoder and a 8 digit
display so i reckon it is not hard to allow for using the counter the other
way around. This will satisfy all need for high frequency clock signals,
precise and TTL.
Tell me more about this?
So if it works out i only need the generator for sine and higher amplitude
things.
That's a key, figure out what you want to use it for first! :-)
thanks for making me think about what makes sense to build and what not,
sometimes i overshoot the target.
It's easy to do when you're sitting there playing with ideas, and lose track
of what you would or wouldn't do with most of those features.
