How to make a Voltage Controlled Oscillator

[Rich Grise]

Vladimir Vassilevsky:

He said "seventies" and "2001 just released".

But he also did not mention "not readily available".

http://en.wikipedia.org/wiki/File:SCELBI_8H_Front.jpg
http://userwww.sfsu.edu/~hl/c.Scelbi8H.html
http://commons.wikimedia.org/wiki/File:SCELBI_8H_Computer.jpg
http://www.thepcmuseum.net/newspage.php?RECORD_KEY(news)=id&id(news)=2
http://www.thepcmuseum.net/details.php?RECORD_KEY(museum)=id&id(museum)=22
http://www.history-computer.com/ModernComputer/Personal/Scelbi.html

Hope This Helps!
Rich

 

[Rich Grise]

Could it be 8880 ?

Fer Cry's sakes, how many times do I have to tell you guys? It was a
Scelbi 8H, with an intel 8008 - that's eight, zero, zero, eight. Mine
only came with 256 bytes of RAM. And I didn't technically buy it. I
had just plunked down about $600.00 for a Heathkit IO-10 or maybe IO-11;
It was really cool looking; similar to a TEK 465, i.e., low aspect ratio
(or high - about a foot wide by about 5" tall by about 17" deep)

And when I assembled it, it didn't work. But a coworker had the Scelbi
which he didn't like having to toggle everything in, but it had cost
him about 6 bills, so we traded straight up. He also gifted me with
a model 13 teletyps. (60 mA current loop, 60 WPM.)

8008 machine code is almost microcode, but it did have an 8-level stack. ;-)

Cheers!
Rich

 

[F. Bertolazzi]

F. Bertolazzi:

Seen in retrospect, I should have saved the time & money it took.

I found the prototype!
http://it.tinypic.com/view.php?pic=5z42u&s=7

The NE555 was the metronome, adjustable with the blue trimmer.
One of the buttons was for changing tune, the other... who knows.

Lazy kid (well, the program was written in hex codes painfully typed on a
friend's eprom programmer), I used a brand new 8253 (look at the date
stamp!) to make the notes, three at a time!!! The resistors near the 2n1711
were the mixer. The greasy label on the Z-80 had the pin names written on
it.

 

[F. Bertolazzi]

Rich Grise:

http://en.wikipedia.org/wiki/File:SCELBI_8H_Front.jpg

That reminds me the hours it took to load (and reload and again) the boot
memory of the Varian microcomputer used as collision avoidance system.

 

[F. Bertolazzi]

Rich Grise:

Fer Cry's sakes, how many times do I have to tell you guys?

Hey, not me! I was even convinced that the 8008 was released before 1970
(as 2001 was).

 

[[email protected]]

Rich Grise:


Hey, not me! I was even convinced that the 8008 was released before 1970
(as 2001 was).

But spring of '68? Nope, not buying that one! ;-)

 

[Rich Grise]

Hey, not me! I was even convinced that the 8008 was released before 1970
(as 2001 was).

But spring of '68? Nope, not buying that one! ;-)[/QUOTE]

FWIW, when I got mine, it was in 1972 or '73.

Cheers!
Rich

 

[[email protected]]

FWIW, when I got mine, it was in 1972 or '73.

"2001 - A Space Odessy" Came out in April '68 and the 8008 was introduced in
April of '72, a full four years later. Sorry, we're not buying your "Daisy
Daisy" on the 8008 "shortly after the release of "2001: A Space Odyssey."".
;-)

 

[josephkk]

Cem Uzunoglu:


You can't hear notes that high. 66 Hz - 5 kHz will do.

Maybe you can't, i still can. I could hear sine tones past 22,000 Hz as a
teen.

 

[Bill Sloman]

A Schmitt inverter, 1 cap, and 1 resistor.

Sadly, that's just an oscillator, rather than a voltage controlled oscillator.

The VCO in CD4046/MC14046 is about as simple as it gets. You get a few extra components in the package, but you can ignore them.

Voltage-to-frequency converters are even simpler, but tend to be more expensive these days.

 

[Tim Williams]

Well, if you add another resistor, you'll get a VCO. It won't be linear,
but hey... the guy said "simplest"!

I would, of course, take that one step further by reducing the schmitt
trigger (which might be, say, 6 transistors for a CMOS) to a pair of
transistors, or anything with negative resistance (tunnel diode, neon
tube..).

Tim