oscilloscope hookup? ?

Started by Ivan Vegvary March 30, 2015
Trying to find hookup instructions for using an older oscilloscope  (heathkit) to do
auto ignition analysis. (1948 Pontiac, 8cyl).
Searched the web to no avail. All advice appreciated. 
Ivan Vegvary 
On Mon, 30 Mar 2015 07:12:52 -0700, Ivan Vegvary wrote:

> Trying to find hookup instructions for using an older oscilloscope > (heathkit) to do auto ignition analysis. (1948 Pontiac, 8cyl). Searched > the web to no avail. All advice appreciated. Ivan Vegvary
I was given an old Champion scope to 'look at'. Trigger the scope with an inductive pickup on #1 plug lead, and observe the coil output (center distributor) through an El Hugeo (big-ass) resistor. You should see a string of 8 pulses, and you can compare the shapes to evaluate each cyl. Search the Champion spark-plug info for pulse shapes etc. This is all I know about that!
On Monday, March 30, 2015 at 8:58:27 AM UTC-7, Wond wrote:
> On Mon, 30 Mar 2015 07:12:52 -0700, Ivan Vegvary wrote: > > > Trying to find hookup instructions for using an older oscilloscope > > (heathkit) to do auto ignition analysis. (1948 Pontiac, 8cyl). Searched > > the web to no avail. All advice appreciated. Ivan Vegvary > > ... Trigger the scope with > an inductive pickup on #1 plug lead, and observe the coil output (center > distributor) through an El Hugeo (big-ass) resistor.
NO! That 'center distributor' is tens of kilovolts, rather probe the primary (low voltage) side of the coil (it'll be a few hundred volts, might be wise to plan for +12V... -500V and use a resistive voltage divider). The 'inductive pickup' is a very sloppy current transformer, you want a small-value burden resistor on its secondary (and the primary is just a #1 plug wire threaded through the open center of the C-I transformer core).
I would pick it up capacitively. No tampering with the system and it will protect
the scope. 

Actually the main thing that type of scope shows you is cylinder balance when it
comes to compression ratio. If you are at the coil wire, the higher spikes indicate
higher cylinder pressure at the time of firing. 
On Mon, 30 Mar 2015 15:41:11 -0700 (PDT), jurb6006@gmail.com wrote:

>I would pick it up capacitively. No tampering with the system and it will protect
the scope. roger that . If the probe is near the wires you'll have plenty of signal. I'd wrap a few turns of insulated wire on the insulated HT lead and use a times ten probe.
> >Actually the main thing that type of scope shows you is cylinder balance when it
comes to compression ratio. If you are at the coil wire, the higher spikes indicate higher cylinder pressure at the time of firing.
On Mon, 30 Mar 2015 07:12:52 -0700 (PDT), Ivan Vegvary
<ivanvegvary@gmail.com> wrote:

>Trying to find hookup instructions for using an older oscilloscope (heathkit) to
do auto ignition analysis. (1948 Pontiac, 8cyl).
>Searched the web to no avail. All advice appreciated. >Ivan Vegvary
You don't say which scope you have. The heath CO-1015 Ignition analyzer? The manual is on ebay, http://tinyurl.com/o7qxc2f I'd guess you just aren't looking very hard, because I've managed to find a lot of old Heathkit manuals on line. I'm generally just looking for schematics, but sometimes the whole manual is there. AND utoob has the heath ignition analyzer and shows something about the setup. But do tell the model number of the scope. I did see a reference to an inductive pickup (not capacitive like I suggested and like I've been using with my cheap Elenco scope)
On Tuesday, March 31, 2015 at 6:23:13 AM UTC-7, default wrote:
> On Mon, 30 Mar 2015 07:12:52 -0700 (PDT), Ivan Vegvary > <ivanvegvary@gmail.com> wrote: > > >Trying to find hookup instructions for using an older oscilloscope (heathkit) to
do auto ignition analysis. (1948 Pontiac, 8cyl).
> >Searched the web to no avail. All advice appreciated. > >Ivan Vegvary > > You don't say which scope you have. The heath CO-1015 Ignition > analyzer? The manual is on ebay, http://tinyurl.com/o7qxc2f > > I'd guess you just aren't looking very hard, because I've managed to > find a lot of old Heathkit manuals on line. I'm generally just > looking for schematics, but sometimes the whole manual is there. > > AND utoob has the heath ignition analyzer and shows something about > the setup. > > But do tell the model number of the scope. > I did see a reference to an inductive pickup (not capacitive like I > suggested and like I've been using with my cheap Elenco scope)
Thank you, Default The scope is a Heathkit Model 10-18. I do have the manual, it is not an automotive scope. Please clarify. Wrap a wirt around the hight tension lead from coil to distributer, and, from that wire make a connection to the scope input. Ground the other scope input to chassis ground? I also have an 'inductive' clip on that I can borrow from my timing light. Would that be better? Thank you very much for your comments. Ivan Vegvary
On Tue, 31 Mar 2015 19:03:26 -0700 (PDT), Ivan Vegvary
<ivanvegvary@gmail.com> wrote:

>On Tuesday, March 31, 2015 at 6:23:13 AM UTC-7, default wrote: >> On Mon, 30 Mar 2015 07:12:52 -0700 (PDT), Ivan Vegvary >> <ivanvegvary@gmail.com> wrote: >> >> >Trying to find hookup instructions for using an older oscilloscope (heathkit)
to do auto ignition analysis. (1948 Pontiac, 8cyl).
>> >Searched the web to no avail. All advice appreciated. >> >Ivan Vegvary >> >> You don't say which scope you have. The heath CO-1015 Ignition >> analyzer? The manual is on ebay, http://tinyurl.com/o7qxc2f >> >> I'd guess you just aren't looking very hard, because I've managed to >> find a lot of old Heathkit manuals on line. I'm generally just >> looking for schematics, but sometimes the whole manual is there. >> >> AND utoob has the heath ignition analyzer and shows something about >> the setup. >> >> But do tell the model number of the scope. >> I did see a reference to an inductive pickup (not capacitive like I >> suggested and like I've been using with my cheap Elenco scope) > >Thank you, Default >The scope is a Heathkit Model 10-18. I do have the manual, it is not an automotive
scope.
>Please clarify. Wrap a wirt around the hight tension lead from coil to
distributer, and, from that wire make a connection to the scope input. Ground the other scope input to chassis ground?
>I also have an 'inductive' clip on that I can borrow from my timing light. Would
that be better?
> >Thank you very much for your comments.
You probably mean your scope is an IO18 (India Oscar -not 10) a tube type scope? http://www.vintage-radio.info/download.php?id=722 Looking up the Heath ignition analyzer http://www.vintage-radio.info/download.php?id=537 They show an inductive pickup, feeding a transistor type vertical amp. I can't say if the inductive pickup on your timing light will work but if you don't mind the effort of trying it, it should (may) produce better results since it is a low impendence source, the signal should reflect the actual wave form closer than a high Z capacitive pickup. I generally wrap some 22 gauge insulated solid hookup wire around the coil lead for 1/2" wide, and twist the ends so it stays tight without moving then connect one stripped end to the scope and leave the other floating. Scope gets grounded to the motorcycle chassis. My bike has two coils and four high tension spark plug wires - so there's no syncing involved, but my scope has two channels and I can compare two ignition wire signals. You might want to sync on one HT (#1 cyl) lead, then put the vertical input on the coil wire, which would require two pickups. (distributor ignition and multiple cylinders) The schematic for the CO-1015 shows one inductive pickup then a wire running off to a "secondary pickup clamp" (presumably another pickup for syncing) It will probably take some tinkering before you have what you want. My problem is working outdoors and scope brightness becomes another issue. A heavy dark cloth like the old view cameras used to focus on ground glass works. The signal on the primary of the coil may be up to ~400 volts with the inductive kick and the ringing with the condenser in the kilo-hertz range. Good luck.
Default, thank you for the time you have invested in this.  Will try your
suggestions as soon as it stops raining. (Northwest ).
BTW I am working on an 8 cylinder 1948 Pontiac, however, it is good to know that
your technique also applies to my vintage 1964 BMW cycle. 
Thanks again. 
On Wed, 1 Apr 2015 07:03:45 -0700 (PDT), Ivan Vegvary
<ivanvegvary@gmail.com> wrote:

>Default, thank you for the time you have invested in this. Will try your
suggestions as soon as it stops raining. (Northwest ).
>BTW I am working on an 8 cylinder 1948 Pontiac, however, it is good to know that
your technique also applies to my vintage 1964 BMW cycle.
>Thanks again.
I covered most of the country on a 71 Triumph and bought a 72 BMW in 73, when I got to California. The bmw bike transited the country a few times.