Heathkit oscilloscope FIXED !!

[Ivan Vegvary]

Heathkit IO-18

Thanks everyone for the help/advice in fixing the above. Problem was the 1V2 tube. Saw a deal on E-Bay (5 tubes for $12). Took a chance. They all seemed brand new (with boxes) and all tested well in the scope. Now I don't know what to do with the other 4 leftovers.
Now I need something to use the scope on. Are there any simple signal generators (on the web) that can be built from scratch? Can I watch some low frequency outputs from the handful of 555 timers and other IC's I have on hand? I do have a breadboard and a good stock of oddball resistors and capacitors.

Started a new post because the previous one got too ugly.

Thanks again.

Ivan Vegvary

 

[Jon Kirwan]

Heathkit IO-18

Thanks everyone for the help/advice in fixing the above.
Problem was the 1V2 tube. Saw a deal on E-Bay (5 tubes for
$12). Took a chance. They all seemed brand new (with
boxes) and all tested well in the scope. Now I don't know
what to do with the other 4 leftovers.

Now I need something to use the scope on. Are there any
simple signal generators (on the web) that can be built from
scratch? Can I watch some low frequency outputs from the
handful of 555 timers and other IC's I have on hand? I do
have a breadboard and a good stock of oddball resistors and
capacitors.

I can provide a pre-programmed TI LaunchPad (it cost me
$4.30, so I don't care at all giving it away) that would use
a crystal to provide a variety of frequencies for you.
Voltages would be 0 to +3.6V. It would take me only a few
moments to write up the code for it. I think we live nearby
so I could drive it over and would be glad to do that. You'd
get good-accuracy signals. Just let me know what you'd like
to have as signal outputs.

Jon

 

[JW]

Heathkit IO-18

Thanks everyone for the help/advice in fixing the above. Problem was the 1V2 tube. Saw a deal on E-Bay (5 tubes for $12). Took a chance. They all seemed brand new (with boxes) and all tested well in the scope. Now I don't know what to do with the other 4 leftovers.
Now I need something to use the scope on. Are there any simple signal generators (on the web) that can be built from scratch? Can I watch some low frequency outputs from the handful of 555 timers and other IC's I have on hand? I do have a breadboard and a good stock of oddball resistors and capacitors.

Started a new post because the previous one got too ugly.

Thanks again.

Ivan Vegvary

You might take a look at the Exar XR-8038 waveform generator chip. While
it's been out of production for a long time, they can still be found on
Ebay for less than $5.

 

[JW]

You might take a look at the Exar XR-8038 waveform generator chip. While
it's been out of production for a long time, they can still be found on
Ebay for less than $5.

There's some links here that might be of use.
http://discovercircuits.com/F/function.htm

 

[Bob Masta]

Heathkit IO-18

Now I need something to use the scope on. Are there any simple signal gene=
rators (on the web) that can be built from scratch? Can I watch some low f=
requency outputs from the handful of 555 timers and other IC's I have on ha=
nd? I do have a breadboard and a good stock of oddball resistors and capac=
itors.

You might want to have a look at my Daqarta software, which
uses the sound card in a Windows system to generate signals
(among many other things). As a signal generator it is
absolutely *free*: After the 30-session/30-day trial period
expires, only the signal *inputs* stop working, but the
*outputs* and most other stuff keep working as before.

The Daqarta generator allows all kinds of waveforms (Sine,
Triangle, Ramp, Square, Biphasic Pulse, Arbitrary, Play
recording, uniform White noise, Gaussian, Pink, or
Band-limited noise) plus modulation schemes (Burst, AM. FM.
PM/PWM, Sweep), with 4 independent "streams" per stereo
output channel that can be added in arbitrary proportions.
Or you can use streams to modulate other streams.

You can also see the signal you are generating on the
display, with lots of triggering options, so you can compare
to what your Heathkit shows you.

The downside of using a sound card for this is that they are
AC-coupled, so tops of low-freq square waves droop. Also,
sound cards are limited to the "audio range", though modern
cards (even some cheapies built into inexpensive laptops)
can now sample at 192000 Hz and are thus useful at up to
(nominally) 96000 Hz.

Best regards,


Bob Masta

DAQARTA v7.10
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE Signal Generator, DaqMusic generator
Science with your sound card!

 

[Michael Black]

Ah. In that case then Ivan wants to build a pair of sine wave
oscillators, shove the outputs into the X and Y inputs, and play with
Lissajous patterns. Done right, it could be a room decoration.

I was going to say that, but I couldn't remember if those cheap scopes
(and I had one once, $5.00 at a local ham club auction about 1973, really
heavy, and barely able to handle audio) had a horizontal input.

There are lots of things one can do with one of those, if nothing else
just to get an idea of an oscilliscope. I got my five dollars worth, if
nothing else, learning it wasn't that useful (but it was fun at the time).
Until one can see a need for a scope, it's silly to spend much money, and
difficult to determine what's useful. A scope like this gives some play
time to explore it, even if it is much simpler than will be useful. Just
don't spend a lot of money on them.

Or, modify the horizontal sweep circuit into something that has a trigger.

Those were popular in the seventies, as triggered (to some extent) scopes
came along that were within reach money wise. Suddenly they were almost
in sight, so might as well get some of the function from the old scope.
It also helped that one could use semiconductor devices, so a small board
could be made to fit in the old scope.

Of course there are still limitations, AC coupling, very little frequency
response, but fun.

Soon after, I had the use of a Tektronix scope, the 454? The 100 or
150MHz one that was more horizontal than vertical (sizewise) and was solid
state except for a nuvistor front end. A kid at school saw it, and told
others it was a "multi-color" scope, I'm not sure where he got that,
except besides the trace, it actually had a graticule that lit up.

I've got an OL-1 in my attic that came from my uncle. I think the last
time I used it was about 30 years ago* -- I should learn how to become a
FleaBay vendor and sell it off along with some of my other junk.

* To the damage of my stereo receiver. I didn't know that solid-state
stereo amplifier outputs aren't ground-referenced; I was trying for the
Lissajous patterns between left and right, but what I got was a stereo
receiver with a slightly wonky power supply.

There was the time I hooked a VTVM to a tv set, the transformerless kind.
I knew better, just simply forgot at that moment. The insulation on the
ground lead proceeded to burn up, the actual wire holding. I'm surprised
a fuse didn't blow. I still have that 410B, it was never hurt other than
no insulation on the ground lead.

If we don't admit our stupidity of being young, it won't help the
beginners in making their own mistakes.

Michael

 

[Bob Masta]

On Wed, 28 Nov 2012 12:13:32 -0600, Tim Wescott

* To the damage of my stereo receiver. I didn't know that solid-state
stereo amplifier outputs aren't ground-referenced; I was trying for the
Lissajous patterns between left and right, but what I got was a stereo
receiver with a slightly wonky power supply.

Not ground-referenced? I think 30 years ago (if not today
as well) the amp outputs of most "home stereo" receivers
were ground referenced. Some cheapie units (and probably
most car stereo units) used bridge mode, I imagine.

But I'd guess the problem was that the scope *was* ground
referenced, and that trying to do a differential measurement
with a single-ended scope just shorted one channel of the
amp to ground. (Been there, done that!)

Best regards,


Bob Masta

DAQARTA v7.10
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE Signal Generator, DaqMusic generator
Science with your sound card!