"W3JDR" writes:

...the group IS called "rec.radio.amateur.homebrew"..isn't it?. Why would
someone be advised to buy when he asks for advice in a group dedicated to
building???

Joe

And it is fund to build stuff. The old sig gens were pretty simple, with
most of the hard work on the dial. The Eico 320 was pretty popular and
you can use the manual to build one of your own:
http://www.nostalgiaair.org/Referenc.../EIC/EIC_8.zip

But you can replace the triodes with fets, lower the voltage to 12 volts and
get the same results.

Steve.
--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA

A lot of the modern signal generator projects are based on the Analog
Devices AD9850. Analog Devices actually encourages hams to use their sample
service, so the part itself is no problem. It is relatively simple to
program, so you may choose the microcontroller of your choice, although most
of the projects out there seem to lean toward the PIC.

The challenge could well be the circuit board. The 9850 is only available
in TSSOP so you need a good quality circuit board to attach it to. If your
PCB skills are good this won't be a problem. But if not, you might need to
hunat around for a protoboard or something of that ilk that you can get in
your location. Unfortunately, these tend to be kind of pricey.

...

"Steven Swift" wrote in message
...
"W3JDR" writes:

...the group IS called "rec.radio.amateur.homebrew"..isn't it?. Why would
someone be advised to buy when he asks for advice in a group dedicated to
building???

Joe

And it is fund to build stuff. The old sig gens were pretty simple, with
most of the hard work on the dial. The Eico 320 was pretty popular and
you can use the manual to build one of your own:
http://www.nostalgiaair.org/Referenc.../EIC/EIC_8.zip

But you can replace the triodes with fets, lower the voltage to 12 volts
and
get the same results.

Steve.
--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA

In article ,
says...
A lot of the modern signal generator projects are based on the Analog
Devices AD9850. Analog Devices actually encourages hams to use their sample
service, so the part itself is no problem. It is relatively simple to
program, so you may choose the microcontroller of your choice, although most
of the projects out there seem to lean toward the PIC.

Which is something I can't begin to understand. With the AVRs, you get
a faster chip with an industrial-strength C/C++ compiler that also
happens to be free (as in beer).

I guess some people are just really, really, REALLY into PIC assembly.
There's no other explanation for its popularity in the ham community.

The challenge could well be the circuit board. The 9850 is only available
in TSSOP so you need a good quality circuit board to attach it to. If your
PCB skills are good this won't be a problem. But if not, you might need to
hunat around for a protoboard or something of that ilk that you can get in
your location. Unfortunately, these tend to be kind of pricey.

Actually the AD9850 comes in a SOIC package with 20 pins/inch, or half
the spacing of a normal DIP IC, rather than a TSSOP (0.5 mm lead pitch,
or about 50 pins/inch).

It is not hard to work with a SOIC dead-bug style. TSSOPs are a
different story; they really need to be mounted to a PC board,
especially if there are more than 16 pins to deal with.

-- jm

------------------------------------------------------
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Note: My E-mail address has been altered to avoid spam
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"John Miles" wrote in message
...

Which is something I can't begin to understand. With the AVRs, you get
a faster chip with an industrial-strength C/C++ compiler that also
happens to be free (as in beer).

Well, there are a couple of things here.

First of all, Microchip was early to the game. As a result, there is a lot
of tutorial information out there. Admittedly, a lot of it is really bad,
but it's existence helps people get over the hump. And lets face it,
deploying a microcontroller really isn't very hard, but getting over the
initial fear is. The huge number of PIC projects out there helps people
feel like maybe it isn't so hard.

A second part is the really wonderful simulation capabilities of MPLAB. It
makes it pretty darned easy to see what is going on, and when people are
starting out, that is a pretty big deal. If you look at the hobbyist
project code out there, it looks like 90% or more of them are written by
people "just starting out".

Thirdly is the availability of cheap programmers. Yes, I know the AVR is
even simpler to program than the PIC, but it hasn't drawn literally hundreds
of programmer designs, almost all of which can be built cheaply. This is
another consequence of Microchip being early to the game.

And actually, I think an advantage the PIC has is that, at least for the 16F
PICs, all the C compilers are truly horrid. When you are going to deploy a
microcontroller, any microcontroller, you really need to understand what is
happening at a pretty basic level. Once you have a lot of expertise in a
particular part, then a compiler can be a big productivity boost. But until
you have a lot of expertise, the compiler can really get in the way.
Fortunately for the PIC community, most of the compilers are bad enough that
you're not real tempted to use them.

Actually the AD9850 comes in a SOIC package with 20 pins/inch, or half
the spacing of a normal DIP IC, rather than a TSSOP (0.5 mm lead pitch,
or about 50 pins/inch).

I've never seen a 9850 in an SOIC. That certainly would be easier to use.
Where did you find such a thing? When I check AD's web site, all I see is a
choice whether I want my SSOP's on a reel or not.

...

In article ,
says...
And actually, I think an advantage the PIC has is that, at least for the 16F
PICs, all the C compilers are truly horrid. When you are going to deploy a
microcontroller, any microcontroller, you really need to understand what is
happening at a pretty basic level. Once you have a lot of expertise in a
particular part, then a compiler can be a big productivity boost. But until
you have a lot of expertise, the compiler can really get in the way.
Fortunately for the PIC community, most of the compilers are bad enough that
you're not real tempted to use them.

That's the cool thing about AVR-GCC, though... you really *don't* need
to understand what is happening at a fundamental level. It just plain
works. I've used AVR-GCC chips in a half-dozen projects, some of them
*very* non-trivial, but I wouldn't know a line of AVR assembly if it bit
me.

It certainly doesn't hurt to master your platform's assembly language,
especially if you need every bit of performance the chip can deliver.
But as long as we're talking about hobby applications, I think most of
us can agree that life at the bench is too short to spend it learning
various proprietary assembly languages for no good reason.

Actually the AD9850 comes in a SOIC package with 20 pins/inch, or half
the spacing of a normal DIP IC, rather than a TSSOP (0.5 mm lead pitch,
or about 50 pins/inch).

I've never seen a 9850 in an SOIC. That certainly would be easier to use.
Where did you find such a thing? When I check AD's web site, all I see is a
choice whether I want my SSOP's on a reel or not.

Sorry; you're totally right -- it's not a SOIC, but an SSOP with 0.65 mm
pitch (39 pins/inch).

I've only used the AD9850 in one project, and I've never actually
ordered one -- I lifted mine off an old PC-VFO ISA card from 1998 or so.
Seemed to remember it being a SOIC, but the photos at archive.org show
that it definitely was not. There are other SOICs on the PC-VFO board,
and they have a coarser lead pitch than the DDS chip.

The AD9852/4 chips have the same 0.65 mm pin spacing for the record, but
a heck of a lot more pins.

-- jm

------------------------------------------------------
http://www.qsl.net/ke5fx
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------

"xpyttl" writes:

A lot of the modern signal generator projects are based on the Analog
Devices AD9850. Analog Devices actually encourages hams to use their sample
service, so the part itself is no problem. It is relatively simple to
program, so you may choose the microcontroller of your choice, although most
of the projects out there seem to lean toward the PIC.

The challenge could well be the circuit board. The 9850 is only available
in TSSOP so you need a good quality circuit board to attach it to. If your
PCB skills are good this won't be a problem. But if not, you might need to
hunat around for a protoboard or something of that ilk that you can get in
your location. Unfortunately, these tend to be kind of pricey.


Back in 1996, one of Novatech's early products was a small DDS board based
upon the AD9850. It was later upgraded to the AD9851 to allow higher
output frequency. We no longer build this item, but I looked in the back
stock area and found that there were hundreds of blank boards left. You
can see the schematic at: http://www.novatech-instr.com/Fun/dds6m_sch.pdf
and a photo at: http://novatech-instr.com/images/dds6mf.jpg

If you want one of these blank boards FREE, send a self-address, stamped
($0.60) envelope to:

Novatech Instruments, Inc.
attn: DDS6m board
P.O. Box 55997
Seattle, WA 98155-0997

and I'll get one out to you. The price is right and might get you
over the soldering hump. The discrete parts are 1206, 0805 and 3216.
We have a bunch of the key parts (micros, AD9851BRS, etc), but we'd
have to come up with a price for that.

Steve.

--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA