In , (Michael
Black) wrote:

Frank Gilliland ) writes:

Let me ask you a simple question: Suppose someone buys an SP-600, mounts some
chrome knobs, spray-paints his name on the front panel, then posts on the
newsgroup saying, "Hey, look what I built!" Would you call that "homebrew"?

I think there's a vast difference between that scenario, and building with
ICs. In your example, they are mere cosmetic work. But when building with
an IC, you will have to actually build something around it in order to
get something useful.

I am a bit surprised that you hold this opinion this late in the game.
Clearly, it was not an uncommon opinon thirty or so years ago, when
people would write to the magazines and complain about so many ICs
being used, and about how the internal diagram of the IC was not shown.
A lot of that could be discounted as a transitional reaction, that
since ICs were new people were reacting to the newness rather than
an absolute reaction to ICs being "cheating".

At least thirty years on, it's hard to imagine that there are people
who haven't adapted.

Adapted? Yes. I have built countless devices around IC's of just about every
shape and size. But I didn't design or build the -circuits- (i.e, the amps, the
oscillators, the comparators, the negative impedance converters -- the network
of active and passive components that make the device do what it does), I just
followed the instructions provided with the chip and connected the dots.

As others have pointed out, one can go down through a spiral to an
absolute level of "homebrew", but everything would be pretty bulky then.
Of course, early hams built their capacitors and all that, but it
was more necessity than some hard core belief. Once you could get
commercially available components, then they were used unless
a) someone was curious about making a capacitor or b) what was
exactly needed wasn't available.

The "level" of construction is the issue. It's one thing to homebrew the
components, but another to homebrew the circuits. I understand what you and
everyone else is saying, that "homebrew" can include the use of pre-packaged
circuits as components, that it's just a different "level" of construction. Some
might even think that building something from a kit is homebrew. I don't.
Somebody else "brewed" the circuit -- the kit-builder simply assembles the
components (connects the dots).

There are some borderline parts. It hardly makes sense to buy
a commercially made coil if you can wind one yourself, but that's
not because everyone should be making everything, but because if
someone isn't winding, they may not realize it is a simple thing,
and winding will save money.

What ICs have done is allow for a level of complexity that wasn't
available before them. Sure, there were PLLs described in the ham
magazines using tubes, but they were as complicated as a simple superhet
receiver. I can remember seeing tube based synthesizers, using multiple
crystals mixed together, and they were more complicated than a full
blown transmitter.

Superhets aren't that complicated, and neither is crystal mixing. Regardless,
crystal mixing can get expensive.

If you want to build up a whole synthesizer from transistors, it's
going to be terribly bulky. I suspect few will go to that trouble,
and instead making something simple but which won't give the performance
of a synthesizer.

Not true. Try linearizing a VCO and using a stepped voltage divider, then
beating the output against an OCXO for drift correction. It's an old method, but
it still works great. And it's a lot less complicated and expensive than using
multi-bit comparators, parallel ripple counters, a parallel-to-serial converter
(because there are very few parallel PLL chips anymore), BCD rotory switches or
a decimal-to-binary converter, phase detectors, prescalers, etc. And notice that
you still need that pesky reference oscillator!

There is so much that can be built nowadays that virtually
nobody would consider building in the tube era.

I agree. But I didn't say that every homebrew project must be built with tubes.

So I dismiss your hardcore view on this.

On the other hand, there is validty in constantly thinking through whether
something should be done with transistors or ICs. One shouldn't build
with ICs for the sake of building with them; if two transistors out of
a scrap VCR and some other components from it flash an LED perfectly
well, then what's the point of using an expensive and hard to get
IC that exists only to flash LEDs?

You're getting close....

If you don't lose anything in performance,
and only a little space, then you might as well use readily available scrap
transistors to build an IF strip, than spend money and time buying an
IC via mail order. If two transistors will supply a suitable prescaler
for Harry's project, then it likely is a good choice, because it's
easier to find transistors than prescaler ICs.

That was my point initially.

But these are design decisions, not some rhetoric about how everything
must be made from scratch. Any time something is designed, it's important
not just to look at the way to do it, but at other alternatives, because
people often do get blocked by looking down only one path.

And that, too, is a very good point. Notice that it works both ways -- I see a
lot of homebrewers getting stuck in an 'IC rut'.

For instance, as I write this it occured to me that it might be
easier for Harry to mix the VCO signal down to a frequency where
the average logic IC can work. You don't have to find a prescaler,
and the design's frequency steps won't be limited by the division of
that prescaler. There are various mixer schemes that will result
in the needed frequency. There may be reasons for not doing it this
way, but it may not even be explored because Harry hasn't given this
alternative any thought.

And the synth will be more accurate than using a prescaler, even a dual-modulus
prescaler. But I made the mistake of assuming that he knew the difference
between the two methods and had chosen the prescaler over down-conversion for
reasons unmentioned.





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