MOTM

I finally sat down tonight at got my Tektronix to give me some
waveform views of one of my oscillators. There was more than a little
trial-and-error at first, but once I got in the ballpark I was able to
zero in on clear, static waveforms that changed shape in predictable
and expected ways, which was immensely satisfying (and will no doubt
impress my musical buddies, for whom a MOTM cabinet is already like
seeing something out of Close Encounters - this now adds that last mad
scientist touch).

And I got the onboard frequency counter working, which is a nice plus.

All this was done using a rather painful method whereby I clipped the
ground to one exposed terminal on the end of a phone cable and touched
the probe to the other. While this worked, it was not at all easy to
do one-handed, and clearly not a long-term methodology. What I really
want is to make this kind of connection permanent, ie just have some
sort of probe terminating in a phone plug that I can tap into any jack
without worrying about fiddly connections. Does such a thing exist,
either ready-to-use or in some combination of probes+adaptors?

What do people who know what they're doing do? (he said, and not for
the first time...)

Thanks!
JN

I went to radio shack and bought a bunch of bnc jacks of various types, and attached the business end of a patch cord to one of them. I also made a homebrew probe by taking a switchcraft jack and attaching wires terminating in alligator clips to the appropriate terminals. With these 2 tools, I'm covered. Note - this is NOT what people who know what they're doing do necessarily - consider the fact that i bought my scope on ebay for 21$ (a nice, fully functional heath). Whenever I visit any of our local electronics stores, I contemplate buying some real probes, but then contemplate having a few extra dollars left over, and pass.

On Wed, Jan 28, 2009 at 9:24 PM, jneilnyc <jneil@...> wrote:

I finally sat down tonight at got my Tektronix to give me some
waveform views of one of my oscillators. There was more than a little
trial-and-error at first, but once I got in the ballpark I was able to
zero in on clear, static waveforms that changed shape in predictable
and expected ways, which was immensely satisfying (and will no doubt
impress my musical buddies, for whom a MOTM cabinet is already like
seeing something out of Close Encounters - this now adds that last mad
scientist touch).

And I got the onboard frequency counter working, which is a nice plus.

All this was done using a rather painful method whereby I clipped the
ground to one exposed terminal on the end of a phone cable and touched
the probe to the other. While this worked, it was not at all easy to
do one-handed, and clearly not a long-term methodology. What I really
want is to make this kind of connection permanent, ie just have some
sort of probe terminating in a phone plug that I can tap into any jack
without worrying about fiddly connections. Does such a thing exist,
either ready-to-use or in some combination of probes+adaptors?

What do people who know what they're doing do? (he said, and not for
the first time...)

Thanks!
JN

--
------------------------------------------------------------------
Stephen Drake
sduck409@...
makeme1witheverything@...

I was hoping it was as simple as this! But seeing all the funky
looking probes out there with all the odd connectors and built-in
electronics I just assumed that I was being naive thinking I could
just make a cable.

The Tektronics probes that came with my scope have BNC connectors with
additional contact pins coming out of them - I take it these aren't
necessary in a homebrew cable?

--- In motm@yahoogroups.com, David Abbey <abbeysynth@...> wrote:
>
> Beg, borrow, make or buy yourself a coaxial cable with a BNC
connector on at least one end. Solder a 1/4" phone plug to the other
end (tip to center conductor and sleeve to the braid, but be careful
not to over heat the braid and melt the dielectric). You can break
out a signal with a multiple by routing your signal into one jack,
taking it out of another in that multiple and plugging your 'scope
cable into a third. I made 2 for my 'scope (A and B channels). I
also made one with bananna plugs on one end to use with my DMM.
>
>
>
>
> ________________________________
> From: jneilnyc <jneil@...>
> To: motm@yahoogroups.com
> Sent: Wednesday, January 28, 2009 8:24:37 PM
> Subject: [motm] Scope question
>
>
>
> I finally sat down tonight at got my Tektronix to give me some
> waveform views of one of my oscillators. There was more than a little
> trial-and-error at first, but once I got in the ballpark I was able to
> zero in on clear, static waveforms that changed shape in predictable
> and expected ways, which was immensely satisfying (and will no doubt
> impress my musical buddies, for whom a MOTM cabinet is already like
> seeing something out of Close Encounters - this now adds that last mad
> scientist touch).
>
> And I got the onboard frequency counter working, which is a nice plus.
>
> All this was done using a rather painful method whereby I clipped the
> ground to one exposed terminal on the end of a phone cable and touched
> the probe to the other. While this worked, it was not at all easy to
> do one-handed, and clearly not a long-term methodology. What I really
> want is to make this kind of connection permanent, ie just have some
> sort of probe terminating in a phone plug that I can tap into any jack
> without worrying about fiddly connections. Does such a thing exist,
> either ready-to-use or in some combination of probes+adaptors?
>
> What do people who know what they're doing do? (he said, and not for
> the first time...)
>
> Thanks!
> JN
>

The way I did it way too many moons ago was to get a BNC to RCA adaptor and then use a cable with an RCA connector on one end and a 1/4" connector on the other. Another option is BNC-RCA adaptor --> RCA-RCA cable --> RCA-1/4" adaptor.

James




To: motm@yahoogroups.com
From: jneil@...
Date: Thu, 29 Jan 2009 05:50:04 +0000
Subject: [motm] Re: Scope question

This might be the ticket:

http://www.testpath.com/Items/BNC-Female-to-14-in-Audio-Phone-Plug-Adapter-112-130.htm

--- In motm@yahoogroups.com, JAMES GALLANT <middlearthling@...> wrote:
>
>
> The way I did it way too many moons ago was to get a BNC to RCA
adaptor and then use a cable with an RCA connector on one end and a
1/4" connector on the other. Another option is BNC-RCA adaptor -->
RCA-RCA cable --> RCA-1/4" adaptor.
>
> James
>
>
>
>
> To: motm@...: jneil@...: Thu, 29 Jan 2009 05:50:04 +0000Subject:
[motm] Re: Scope question
>
>
>
> I was hoping it was as simple as this! But seeing all the
funkylooking probes out there with all the odd connectors and
built-inelectronics I just assumed that I was being naive thinking I
couldjust make a cable.The Tektronics probes that came with my scope
have BNC connectors withadditional contact pins coming out of them - I
take it these aren'tnecessary in a homebrew cable?--- In
motm@yahoogroups.com, David Abbey <abbeysynth@> wrote:>> Beg, borrow,
make or buy yourself a coaxial cable with a BNCconnector on at least
one end. Solder a 1/4" phone plug to the otherend (tip to center
conductor and sleeve to the braid, but be carefulnot to over heat the
braid and melt the dielectric). You can breakout a signal with a
multiple by routing your signal into one jack,taking it out of another
in that multiple and plugging your 'scopecable into a third. I made 2
for my 'scope (A and B channels). Ialso made one with bananna plugs on
one end to use with my DMM.> > > > > ________________________________>
From: jneilnyc <jneil@>> To: motm@yahoogroups.com> Sent: Wednesday,
January 28, 2009 8:24:37 PM> Subject: [motm] Scope question> > > > I
finally sat down tonight at got my Tektronix to give me some> waveform
views of one of my oscillators. There was more than a little>
trial-and-error at first, but once I got in the ballpark I was able
to> zero in on clear, static waveforms that changed shape in
predictable> and expected ways, which was immensely satisfying (and
will no doubt> impress my musical buddies, for whom a MOTM cabinet is
already like> seeing something out of Close Encounters - this now adds
that last mad> scientist touch). > > And I got the onboard frequency
counter working, which is a nice plus.> > All this was done using a
rather painful method whereby I clipped the> ground to one exposed
terminal on the end of a phone cable and touched> the probe to the
other. While this worked, it was not at all easy to> do one-handed,
and clearly not a long-term methodology. What I really> want is to
make this kind of connection permanent, ie just have some> sort of
probe terminating in a phone plug that I can tap into any jack>
without worrying about fiddly connections. Does such a thing exist,>
either ready-to-use or in some combination of probes+adaptors? > >
What do people who know what they're doing do? (he said, and not for>
the first time...)> > Thanks!> JN>
>

From: motm@yahoogroups.com [mailto:motm@yahoogroups.com] On Behalf Of jneilnyc
Sent: Wednesday, January 28, 2009 8:25 PM
To: motm@yahoogroups.com
Subject: [motm] Scope question

I finally sat down tonight at got my Tektronix to give me some
waveform views of one of my oscillators. There was more than a little
trial-and-error at first, but once I got in the ballpark I was able to
zero in on clear, static waveforms that changed shape in predictable
and expected ways, which was immensely satisfying (and will no doubt
impress my musical buddies, for whom a MOTM cabinet is already like
seeing something out of Close Encounters - this now adds that last mad
scientist touch).

And I got the onboard frequency counter working, which is a nice plus.

All this was done using a rather painful method whereby I clipped the
ground to one exposed terminal on the end of a phone cable and touched
the probe to the other. While this worked, it was not at all easy to
do one-handed, and clearly not a long-term methodology. What I really
want is to make this kind of connection permanent, ie just have some
sort of probe terminating in a phone plug that I can tap into any jack
without worrying about fiddly connections. Does such a thing exist,
either ready-to-use or in some combination of probes+adaptors?

What do people who know what they're doing do? (he said, and not for
the first time...)

Thanks!
JN

The extra pins on a tek scope probe typically indicate to the
scope what type of probe is attached, specifically the
attenuation of the probe (usually x1 or x10). This allows the
on screen display of voltage levels (assuming your scope
supports that) to be scaled appropriately. So when you measure
a 5V signal with your x10 probe, the scope displays it as
5V and not 0.5V.

All you need (as others have mentioned) is a BNC cable with
an appropriate plug on the end. Go buy a 6' to 12' BNC to BNC
cable, and then cut it in half. Put 1/4 plugs on the cut ends
and you have two cables to hook up your scope and make
lissajous patterns...

--- On Wed, 1/28/09, jneilnyc <jneil@...> wrote:

From: jneilnyc <jneil@...>
Subject: [motm] Re: Scope question
To: motm@yahoogroups.com
Date: Wednesday, January 28, 2009, 9:50 PM

I was hoping it was as simple as this! But seeing all the funky
looking probes out there with all the odd connectors and built-in
electronics I just assumed that I was being naive thinking I could
just make a cable.

The Tektronics probes that came with my scope have BNC connectors with
additional contact pins coming out of them - I take it these aren't
necessary in a homebrew cable?

--- In motm@yahoogroups. com, David Abbey <abbeysynth@ ...> wrote:
>
> Beg, borrow, make or buy yourself a coaxial cable with a BNC
connector on at least one end. Solder a 1/4" phone plug to the other
end (tip to center conductor and sleeve to the braid, but be careful
not to over heat the braid and melt the dielectric). You can break
out a signal with a multiple by routing your signal into one jack,
taking it out of another in that multiple and plugging your 'scope
cable into a third. I made 2 for my 'scope (A and B channels). I
also made one with bananna plugs on one end to use with my DMM.
>
>
>
>
> ____________ _________ _________ __
> From: jneilnyc <jneil@...>
> To: motm@yahoogroups. com
> Sent: Wednesday, January 28, 2009 8:24:37 PM
> Subject: [motm] Scope question
>
>
>
> I finally sat down tonight at got my Tektronix to give me some
> waveform views of one of my oscillators. There was more than a little
> trial-and-error at first, but once I got in the ballpark I was able to
> zero in on clear, static waveforms that changed shape in predictable
> and expected ways, which was immensely satisfying (and will no doubt
> impress my musical buddies, for whom a MOTM cabinet is already like
> seeing something out of Close Encounters - this now adds that last mad
> scientist touch).
>
> And I got the onboard frequency counter working, which is a nice plus.
>
> All this was done using a rather painful method whereby I clipped the
> ground to one exposed terminal on the end of a phone cable and touched
> the probe to the other. While this worked, it was not at all easy to
> do one-handed, and clearly not a long-term methodology. What I really
> want is to make this kind of connection permanent, ie just have some
> sort of probe terminating in a phone plug that I can tap into any jack
> without worrying about fiddly connections. Does such a thing exist,
> either ready-to-use or in some combination of probes+adaptors?
>
> What do people who know what they're doing do? (he said, and not for
> the first time...)
>
> Thanks!
> JN
>

I've been getting by with the simple approach of just clipping a 10x
probe to a 1/4-inch plug without its housing. I like the idea of
preserving the impedance features of the probe, rather than just
connecting directly to the scope BNC input.

Richard Brewster
http://www.pugix.com

Adam Schabtach wrote:

> Aside from all of the suggestions that have been aired for connecting
> a 1/4"audio plug to a BNC connector, there's another solution that's
> somewhat more flexible: buy a scope probe with a clip-on probe
> cover, then clip it to a 1/4" plug with its shell removed. This will
> give you hands-free operation with both the 1/4" plug and anything
> else you need to look at with a scope.
>
> Here's a random example of what I'm talking about:
> http://www.testpath.com/Items/Passive-Oscilloscope-Probe-15MHz-X1-110-564.htm
> (No, I've never used that particular probe. It was just the first
> example I found.)
>
> --Adam
>
> ------------------------------------------------------------------------
> *From:* motm@yahoogroups.com [mailto:motm@yahoogroups.com] *On
> Behalf Of *jneilnyc
> *Sent:* Wednesday, January 28, 2009 8:25 PM
> *To:* motm@yahoogroups.com
> *Subject:* [motm] Scope question
>
>
> I finally sat down tonight at got my Tektronix to give me some
> waveform views of one of my oscillators. There was more than a little
> trial-and-error at first, but once I got in the ballpark I was able to
> zero in on clear, static waveforms that changed shape in predictable
> and expected ways, which was immensely satisfying (and will no doubt
> impress my musical buddies, for whom a MOTM cabinet is already like
> seeing something out of Close Encounters - this now adds that last mad
> scientist touch).
>
> And I got the onboard frequency counter working, which is a nice plus.
>
> All this was done using a rather painful method whereby I clipped the
> ground to one exposed terminal on the end of a phone cable and touched
> the probe to the other. While this worked, it was not at all easy to
> do one-handed, and clearly not a long-term methodology. What I really
> want is to make this kind of connection permanent, ie just have some
> sort of probe terminating in a phone plug that I can tap into any jack
> without worrying about fiddly connections. Does such a thing exist,
> either ready-to-use or in some combination of probes+adaptors?
>
> What do people who know what they're doing do? (he said, and not for
> the first time...)
>
> Thanks!
> JN
>
>

You can always put a series resistor in the plug body if you're really
concerned. Most scopes have a 1M input impedance. The method
I described is really a X1 probe with some pF's of capacitance/ft due to the
coax. For audio frequencies it probably isn't going too matter much.
Put a 9M resistor in series in the plug and you have a X10 probe.

Note many Tek scopes aren't going to recognize it as a X10 probe
due to the autosense mentioned earlier.

(If you really want to compensate it, you can put a little (variable)
cap inside the plug body as well.)

--- On Thu, 1/29/09, Richard Brewster <pugix@...> wrote:

From: Richard Brewster <pugix@...>
Subject: Re: [motm] Scope question
To: lists@...
Cc: motm@yahoogroups.com
Date: Thursday, January 29, 2009, 4:37 PM

I've been getting by with the simple approach of just clipping a 10x
probe to a 1/4-inch plug without its housing. I like the idea of
preserving the impedance features of the probe, rather than just
connecting directly to the scope BNC input.

Richard Brewster
http://www.pugix. com

Adam Schabtach wrote:
> Aside from all of the suggestions that have been aired for connecting
> a 1/4"audio plug to a BNC connector, there's another solution that's
> somewhat more flexible: buy a scope probe with a clip-on probe
> cover, then clip it to a 1/4" plug with its shell removed. This will
> give you hands-free operation with both the 1/4" plug and anything
> else you need to look at with a scope.
>
> Here's a random example of what I'm talking about:
> http://www.testpath .com/Items/ Passive-Oscillos cope-Probe- 15MHz-X1- 110-564.htm
> (No, I've never used that particular probe. It was just the first
> example I found.)
>
> --Adam
>
> ------------ --------- --------- --------- --------- --------- -
> *From:* motm@yahoogroups. com [mailto:motm@yahoogroups. com] *On
> Behalf Of *jneilnyc
> *Sent:* Wednesday, January 28, 2009 8:25 PM
> *To:* motm@yahoogroups. com
> *Subject:* [motm] Scope question
>
>
> I finally sat down tonight at got my Tektronix to give me some
> waveform views of one of my oscillators. There was more than a little
> trial-and-error at first, but once I got in the ballpark I was able to
> zero in on clear, static waveforms that changed shape in predictable
> and expected ways, which was immensely satisfying (and will no doubt
> impress my musical buddies, for whom a MOTM cabinet is already like
> seeing something out of Close Encounters - this now adds that last mad
> scientist touch).
>
> And I got the onboard frequency counter working, which is a nice plus.
>
> All this was done using a rather painful method whereby I clipped the
> ground to one exposed terminal on the end of a phone cable and touched
> the probe to the other. While this worked, it was not at all easy to
> do one-handed, and clearly not a long-term methodology. What I really
> want is to make this kind of connection permanent, ie just have some
> sort of probe terminating in a phone plug that I can tap into any jack
> without worrying about fiddly connections. Does such a thing exist,
> either ready-to-use or in some combination of probes+adaptors?
>
> What do people who know what they're doing do? (he said, and not for
> the first time...)
>
> Thanks!
> JN
>
>

This is the technique that I have used with success.

George

Adam Schabtach wrote:

> Aside from all of the suggestions that have been aired for connecting a
> 1/4"audio plug to a BNC connector, there's another solution that's
> somewhat more flexible: buy a scope probe with a clip-on probe
> cover, then clip it to a 1/4" plug with its shell removed. This will
> give you hands-free operation with both the 1/4" plug and anything else
> you need to look at with a scope.
>
> Here's a random example of what I'm talking about:
> http://www.testpath.com/Items/Passive-Oscilloscope-Probe-15MHz-X1-110-564.htm
> (No, I've never used that particular probe. It was just the first
> example I found.)
>
> --Adam

<snip>

I've got a mult panel (a copy of the MOTM-910 cascaded multiple) that
I made with two BNC connectors. This allows me to look at any AC or
DC voltage patched in the system or add an external voltage from my
lab equipment.

You'll need a multiple connection panel sooner or later...

Chub, destroyer of ivy.

Have you got a part number for a BNC connector that fits into a 3/8-inch
jack hole?

Thanks,

Richard Brewster

Charles Osthelder wrote:

> I've got a mult panel (a copy of the MOTM-910 cascaded multiple) that
> I made with two BNC connectors. This allows me to look at any AC or
> DC voltage patched in the system or add an external voltage from my
> lab equipment.
>
> You'll need a multiple connection panel sooner or later...
>
> Chub, destroyer of ivy.
>

Chub meant to send this to the list.

Charles Osthelder wrote:

> OK, I should have replied to the group. I answered Richard from my
> home email:
>
> "Amphenol part number 112424 (Mouser # 573-112424) is the closest
> you'll get, as far as I know. You really want a "D"-shaped hole,
> though. Otherwise you'll be re-tightening the connector a lot and
> that means pulling the panel.
>
> I made my own panel. Two BNCs, each wired to three 1/4" sockets.
> Below that are eight 1/4" sockets in the MOTM cascade arrangement."
>
> This actually gets a lot of use. There is a small oscilloscope
> patched into the Engine of Chaos at all times. When people come to
> see it, I can easily teach them about waveforms that they can see as
> well as hear. It's also nice to understand the results I'm hearing
> when things aren't as expected - you think you've got a bad module
> only to find that your patch makes a noise out of the range of human
> hearing! Trust me, I'm not always too clever...
>
> You can buy a simple banana-to-BNC adapter for patching in modules and
> test gear with that format as well. My favorite is the Pomona 1296 -
> Mouser part number 565-1296. It allows multiple stacks and the banana
> jacks are also binding posts for bare wire. $13.70 apiece but worth it!
>
> Remember - the more wires and cables you have hanging off your system,
> the more likely that people will just leave you alone in your room.
>
> Chub - from deep within the evil lair
>
>
> --- In motm@yahoogroups.com, Richard Brewster <pugix@...> wrote:
>
>> Have you got a part number for a BNC connector that fits into a
>>
> 3/8-inch
>
>> jack hole?
>>
>> Thanks,
>>
>> Richard Brewster
>>
>> Charles Osthelder wrote:
>>
>>> I've got a mult panel (a copy of the MOTM-910 cascaded multiple) that
>>> I made with two BNC connectors. This allows me to look at any AC or
>>> DC voltage patched in the system or add an external voltage from my
>>> lab equipment.
>>>
>>> You'll need a multiple connection panel sooner or later...
>>>
>>> Chub, destroyer of ivy.
>>>
>>>
>
>
>
>

Thanks to everyone who responded, it was most helpful. I did end
up getting a couple BNC->phone adaptors and sticking them on some
cheap cables, and things are working fine. I think the actual
measurements are probably off by 10x or whatever, but that's not
really what I need it for scoping MOTM audio.

Speaking of which, I already had a chance to put it to good use the
other day (and by good I mean "as something other than a light show")...

I was getting confusing results from a module as seemingly obvious as
the 910 multiple -- I had misinterpreted the less-than-crystal-clear
note on the product page and signals were showing up where I didn't
expect them and vice versa. Five minutes on the scope and I was able
to see exactly where signals were coming out correctly and where they
were adding together unpredictably, and eventually I divined the
mysteries of the jack logic.

--- In motm@yahoogroups.com, "jneilnyc" <jneil@...> wrote:
>
>
> This might be the ticket:
>
>
http://www.testpath.com/Items/BNC-Female-to-14-in-Audio-Phone-Plug-Adapter-112-130.htm
>
> --- In motm@yahoogroups.com, JAMES GALLANT <middlearthling@> wrote:
> >
> >
> > The way I did it way too many moons ago was to get a BNC to RCA
> adaptor and then use a cable with an RCA connector on one end and a
> 1/4" connector on the other. Another option is BNC-RCA adaptor -->
> RCA-RCA cable --> RCA-1/4" adaptor.
> >
> > James
> >
> >
> >
> >
> > To: motm@: jneil@: Thu, 29 Jan 2009 05:50:04 +0000Subject:
> [motm] Re: Scope question
> >
> >
> >
> > I was hoping it was as simple as this! But seeing all the
> funkylooking probes out there with all the odd connectors and
> built-inelectronics I just assumed that I was being naive thinking I
> couldjust make a cable.The Tektronics probes that came with my scope
> have BNC connectors withadditional contact pins coming out of them - I
> take it these aren'tnecessary in a homebrew cable?--- In
> motm@yahoogroups.com, David Abbey <abbeysynth@> wrote:>> Beg, borrow,
> make or buy yourself a coaxial cable with a BNCconnector on at least
> one end. Solder a 1/4" phone plug to the otherend (tip to center
> conductor and sleeve to the braid, but be carefulnot to over heat the
> braid and melt the dielectric). You can breakout a signal with a
> multiple by routing your signal into one jack,taking it out of another
> in that multiple and plugging your 'scopecable into a third. I made 2
> for my 'scope (A and B channels). Ialso made one with bananna plugs on
> one end to use with my DMM.> > > > > ________________________________>
> From: jneilnyc <jneil@>> To: motm@yahoogroups.com> Sent: Wednesday,
> January 28, 2009 8:24:37 PM> Subject: [motm] Scope question> > > > I
> finally sat down tonight at got my Tektronix to give me some> waveform
> views of one of my oscillators. There was more than a little>
> trial-and-error at first, but once I got in the ballpark I was able
> to> zero in on clear, static waveforms that changed shape in
> predictable> and expected ways, which was immensely satisfying (and
> will no doubt> impress my musical buddies, for whom a MOTM cabinet is
> already like> seeing something out of Close Encounters - this now adds
> that last mad> scientist touch). > > And I got the onboard frequency
> counter working, which is a nice plus.> > All this was done using a
> rather painful method whereby I clipped the> ground to one exposed
> terminal on the end of a phone cable and touched> the probe to the
> other. While this worked, it was not at all easy to> do one-handed,
> and clearly not a long-term methodology. What I really> want is to
> make this kind of connection permanent, ie just have some> sort of
> probe terminating in a phone plug that I can tap into any jack>
> without worrying about fiddly connections. Does such a thing exist,>
> either ready-to-use or in some combination of probes+adaptors? > >
> What do people who know what they're doing do? (he said, and not for>
> the first time...)> > Thanks!> JN>
> >
>