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Heathkit oscilloscope FIXED !!

Started by Ivan Vegvary November 27, 2012
Heathkit IO-18

Thanks everyone for the help/advice in fixing the above.  Problem was the 1=
V2 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 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.

Started a new post because the previous one got too ugly. =20

Thanks again.

Ivan Vegvary
On Tue, 27 Nov 2012 06:35:22 -0800, Ivan Vegvary wrote:

> 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 can certainly look at voltages from your 555 circuit. Check the input impedance -- if it's high enough, you can look at the voltage on the timing cap in your 555, and compare it to the voltage on the output. Is this one of the scopes with a "sync" control instead of a trigger? It'll be a challenge getting your wiggly line lined up, but it can be done. -- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
On Tue, 27 Nov 2012 06:35:22 -0800 (PST), Ivan Vegvary
<ivanvegvary@gmail.com> wrote:

>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
Tim Wescott wrote:
> > Is this one of the scopes with a "sync" control instead of a trigger?
It has a free running sweep. It was a hobby grade or audio scope for a TV shop.
On Tue, 27 Nov 2012 06:35:22 -0800 (PST) Ivan Vegvary
<ivanvegvary@gmail.com> wrote in Message id:
<81e1341a-f0ae-457a-93d7-aeec2bc12391@googlegroups.com>:

>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.
On Wed, 28 Nov 2012 06:00:39 -0500 JW <none@dev.null> wrote in Message id:
<mgrbb85d2oj385st1rksoubr2febo94k75@4ax.com>:

>On Tue, 27 Nov 2012 06:35:22 -0800 (PST) Ivan Vegvary ><ivanvegvary@gmail.com> wrote in Message id: ><81e1341a-f0ae-457a-93d7-aeec2bc12391@googlegroups.com>: > >>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.
There's some links here that might be of use. http://discovercircuits.com/F/function.htm
On Tue, 27 Nov 2012 06:35:22 -0800 (PST), Ivan Vegvary
<ivanvegvary@gmail.com> wrote:

>Heathkit IO-18 >
<snip>
>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!
On Tue, 27 Nov 2012 18:12:48 -0500, Michael A. Terrell wrote:

> Tim Wescott wrote: >> >> Is this one of the scopes with a "sync" control instead of a trigger? > > > It has a free running sweep. It was a hobby grade or audio scope for > a TV shop.
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. Or, modify the horizontal sweep circuit into something that has a trigger. 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. -- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
On Wed, 28 Nov 2012, Tim Wescott wrote:

> On Tue, 27 Nov 2012 18:12:48 -0500, Michael A. Terrell wrote: > >> Tim Wescott wrote: >>> >>> Is this one of the scopes with a "sync" control instead of a trigger? >> >> >> It has a free running sweep. It was a hobby grade or audio scope for >> a TV shop. > > 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
On Wed, 28 Nov 2012 12:13:32 -0600, Tim Wescott
<tim@seemywebsite.com> wrote:

<snip>
>* 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!