Frank Gilliland wrote:


My point was that the art of homebrewing loses something when it's reduced to
just plugging in a chip. Seems like everyone is ignoring how the circuits work
and taking the 'black-box' approach instead. For example, the MAX038 is a chip
that is a ready-made 0-20 MHz function generator with sweep, variable duty
cycle, frequency modulation, and a phase discriminator. I'm sure that sounds
cool to some, but if all you need is a 100 kHz square wave, why not learn how to
build a square-wave oscillator with one or two transistors? And if you want a
function generator, where's the fun in just hooking up power to a chip? That's
not homebrewing, at least not in my book.


I guess you wind your own capacitors, and collect lamp black to make
your own resistors? there are tradeoffs in any project. Sure you could
build a 50 pound toy that uses 200 watts to do a simple project, or do
the same job in a handheld device that runs for weeks off a couple AA
cells.

Homebrewing is using what you can get to build what you want, as well
as to meet the desired specifications. I started working with used parts
in the '60s, but over the years I have moved on to more advanced
projects. My biggest project to date, was building CH 58 TV in Destin,
Florida with mostly defective and damaged 30 to forty year old broadcast
equipment. It was a real challenge finding, or making replacement parts
fore the RCA TTU-25B transmitter, and other old equipment. it was more
of a restoration and homebrew project than it was meeting the deadline
on the FCC construction permit. I ended up working as an engineering
tech at L-3Com/Microdyne working on $80,000 telemetry receivers, and
still design projects at home.

I am working on some kits to allow people to build some test
equipment they can't afford new, and don't need the performance of brand
new Agilent or Tektronix equipment. It is cheaper to use "Chips", rather
than discrete parts in a lot of circuits, and they design works better,
too. Homebrewing should be used to learn something, and if you want to
remain at the lowest level, enjoy yourself, but don't ridicule others
who want to learn newer methods.
--


Michael A. Terrell
Central Florida

Harry,
have a look at the following page:
http://www.xs4all.nl/~barendh/Indexeng.htm
He seem to stock several old Plessey prescalers, and it should keep
you going for a while.

I guess eventually these chips WILL be nowhere to be found within a
few years time but that is evolution....

One non-obsolete chip-source would be Peregrine,
http://www.peregrine-semi.com/prd_pll.html
they have some neat parallell programmed IC's that runs to over 3 GHz.
They are an improved Qualcomm Q3036 which can be found as surplus
And there is several more interesting IC, not only PLL and prescalers
but complete PLL with internal EPROM which keeps the serial programmed
data even if one shut off the power. Great for that miniaturized
project!!

GL
-Lasse SM5GLC
On Fri, 15 Aug 2003 08:26:47 +0200, "Harry \(SM0VPO\)"
wrote:

Harry,
have a look at the following page:
http://www.xs4all.nl/~barendh/Indexeng.htm
He seem to stock several old Plessey prescalers, and it should keep
you going for a while.

I guess eventually these chips WILL be nowhere to be found within a
few years time but that is evolution....

One non-obsolete chip-source would be Peregrine,
http://www.peregrine-semi.com/prd_pll.html
they have some neat parallell programmed IC's that runs to over 3 GHz.
They are an improved Qualcomm Q3036 which can be found as surplus
And there is several more interesting IC, not only PLL and prescalers
but complete PLL with internal EPROM which keeps the serial programmed
data even if one shut off the power. Great for that miniaturized
project!!

GL
-Lasse SM5GLC
On Fri, 15 Aug 2003 08:26:47 +0200, "Harry \(SM0VPO\)"
wrote:

http://www.peregrine-semi.com/prd_prescaler.html

:2 , :4 or :8 DC to 1GHz

Buy online, price seems to be less than $3

-Lasse SM5GLC

http://www.peregrine-semi.com/prd_prescaler.html

:2 , :4 or :8 DC to 1GHz

Buy online, price seems to be less than $3

-Lasse SM5GLC

"Harry - SM0VPO" ) writes:

As stated, the basic problem is getting a chip that is available, cheap and
is likely to be available next year. The MB501 (SA701, MC12022, SP8704) is
now classed as "obsolete" and one of my sources has also dried up. By the
way, the TDA7000 is also obsolete and is soon to be joining the ZN414/5/6
and TCM3105 chips in the depths of obscurity.

BR Harry - SM0VPO


Do they have really cheap FM broadcast band only pocket radios over there,
that tune with one button (and have a second button to reset to the bottom of
the band)?

They're everywhere here, and I've seen them for as low as $1.99 Canadian.
Curious, I bought one at that price. No cermic filter, so it's using
an oddball scheme. My first thought was that it was a TDA7000; as I
mentioned a couple of weeks ago, the number on the IC was barely visible.
So I looked up the TDA7000 on the web (it was easier than digging out
the paper datasheet), and clearly it was not a match. But Signetics
had pointers to a couple of other similar ICs, ie converting down to
70KHz where active filters can be used, and that frequency locked loop
scheme. One of them was a match, if I'm remembering a 7088.

I don't know how the specs generally compare with the TDA7000, but
this IC has the logic in place for the two button tuning scheme.
Obviously these are being put into products (I always wondered if
the TDA7000 actually was put into commercial products), and hence there
is an available source. Maybe not as IC, but the cheap radio is there.
The IC is surface mount, but it's already soldered to a circuit board.
Change the required parts, and you've got the radio or IF strip.

Michael VE2BVW

"Harry - SM0VPO" ) writes:

As stated, the basic problem is getting a chip that is available, cheap and
is likely to be available next year. The MB501 (SA701, MC12022, SP8704) is
now classed as "obsolete" and one of my sources has also dried up. By the
way, the TDA7000 is also obsolete and is soon to be joining the ZN414/5/6
and TCM3105 chips in the depths of obscurity.

BR Harry - SM0VPO


Do they have really cheap FM broadcast band only pocket radios over there,
that tune with one button (and have a second button to reset to the bottom of
the band)?

They're everywhere here, and I've seen them for as low as $1.99 Canadian.
Curious, I bought one at that price. No cermic filter, so it's using
an oddball scheme. My first thought was that it was a TDA7000; as I
mentioned a couple of weeks ago, the number on the IC was barely visible.
So I looked up the TDA7000 on the web (it was easier than digging out
the paper datasheet), and clearly it was not a match. But Signetics
had pointers to a couple of other similar ICs, ie converting down to
70KHz where active filters can be used, and that frequency locked loop
scheme. One of them was a match, if I'm remembering a 7088.

I don't know how the specs generally compare with the TDA7000, but
this IC has the logic in place for the two button tuning scheme.
Obviously these are being put into products (I always wondered if
the TDA7000 actually was put into commercial products), and hence there
is an available source. Maybe not as IC, but the cheap radio is there.
The IC is surface mount, but it's already soldered to a circuit board.
Change the required parts, and you've got the radio or IF strip.

Michael VE2BVW

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.

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.

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.

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

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? 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.

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.

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.

Michael VE2BVW

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.

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.

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.

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

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? 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.

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.

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.

Michael VE2BVW

"Michael Black" wrote in message
...

But when building with
an IC, you will have to actually build something around it in order to
get something useful.
SNIP
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".

Over 30 years ago I homebrewed a PDP-8 work-alike computer. It was based on
the PDP-8 instruction set. I've never seen PDP-8 electrical or detailed
logic diagrams. I used ICs, but none more complex than a 4-bit adder. The
7400-series was then too expensive for me, so I used a cheaper compatible
Signetic series in most cases. My choice to use ICs was based on a desire to
finish the project within a reasonable time - which I did. There would have
been too many parts going all-discrete. Of course discrete transistors were
used as lamp drivers, to drive the core memory select lines, and in the
voltage regulators.

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

Even using simple digital ICs, you have to know a little about the internals
of the family to avoid pitfalls - and to interface to other families. Analog
ICs require more understanding.

SNIP

On the other hand, there is validity in constantly thinking through
whether
something should be done with transistors or ICs.

Or with a $2 microcomputer. IMO, evaluating the trade-off between hardware
and software is just as important. Where should one draw the line?

My hobby RF experience has mostly been limited to VHF frequency converters.

OTOH I assembled the first FM-stereo broadcast station in the Washington DC
area, WHFS 102.3 MHz. The "components" were rather large: an HH Scott stereo
generator, an RCA "iron fireman" FM exciter, and a 1 kW power power
amplifier that had seen service a number of other places. I built a
frequency-multiplier / IPA between the exciter and the 4-400 finals, and the
power supplies including that for the finals. I built the stereo audio
console for the station; my memory is a little hazy after 40 years, but I
think the console used some audio ICs.

SNIP

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.

As someone else said, engineering is making what you want from the parts
that are available.

73 de bob w3otc