Hello all,

years ago I was given a 10 MHz Heathkit oscilloscope.  Both channels work 
fine, and I use it to probe circuit boards powered up on the workbench.  I 
now own an old hobby car with the old fashioned plugs/points/capacitor 
ignition.  Is there any way I could use the 'scope to observe the ignition 
signals, and would there be any value to it, besides academic information?

Thank you in advance for any and all thoughts!

Regards,
Dan 

On Sat, 13 Sep 2008, Dan Beck wrote:

> Hello all,
>
> years ago I was given a 10 MHz Heathkit oscilloscope.  Both channels work
> fine, and I use it to probe circuit boards powered up on the workbench.  I
> now own an old hobby car with the old fashioned plugs/points/capacitor
> ignition.  Is there any way I could use the 'scope to observe the ignition
> signals, and would there be any value to it, besides academic information?
>
That sort of thing was done in the old days, I've never had a car so
I don't know how useful it was, or even if it matters now (I gather
a lot of cars are now beyond the ability of the average person to
do much repair work).

It would have been detailed in countless magazine articles, and
likely in all those "101 Things To Do With Your Oscilliscope".
That sort of book can be quite useful when starting out with
an oscilliscope, you might want to dig up a used copy.

   Michael

On Sat, 13 Sep 2008 08:14:49 -0700, Dan Beck wrote:

> Hello all,
> 
> years ago I was given a 10 MHz Heathkit oscilloscope.  Both channels
> work fine, and I use it to probe circuit boards powered up on the
> workbench.  I now own an old hobby car with the old fashioned
> plugs/points/capacitor ignition.  Is there any way I could use the
> 'scope to observe the ignition signals, and would there be any value to
> it, besides academic information?
> 
> Thank you in advance for any and all thoughts!
> 
> Regards,
> Dan

I've used my 1-channel, 5MHz Heathkit to set the dwell on my '71 Vega, 
and to diagnose problems with a bad throttle sensor on newer cars.  It's 
a lot less direct than using a dwell meter, but you get to see more of 
what's going on.

Use a 10:1 probe, set the voltage scale to lots -o- volts/division, hook 
the thing across the points and -- voila!  You can see not only the 
dwell, but you can see the profile of the low-tension side of the coil as 
it fires.

-- 
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

On Sep 13, 8:14=A0am, "Dan Beck" <biscuitbecks@*nospam*cableone.net>
wrote:


> years ago I was given a 10 MHz Heathkit oscilloscope.
>... own an old hobby car with the old fashioned plugs/points/capacitor
> ignition. =A0Is there any way I could use the 'scope to observe the ignit=
ion
> signals

Two ways.  First, you can look at the primary winding on
the spark coil; the opening of the points will make a
few hundred volts spike (an attenuator probe is wise
here), and the sparkplug firing will determine the trailing
edge of that transient.  Imbalance of cylinders in
breakover voltage  is clearly visible, can be caused by
obvious things (dirty or misgapped plugs) or unobvious
ones (gas mixture in the cylinder changes the breakdown
characteristic).

Second, you can use a clamp-on transformer to monitor the
current through the HV wires (either the wire to
the coil, OR the distributor wires to one plug at a time).
Be careful about grounding here, of course.  A burden
(shunt) resistor on the secondary of your transformer is
VERY IMPORTANT; ten to a hundred ohms should
be sufficient.   The transformer can be a pair of ferrite
core halves and a single turn of wire for the secondary.

"Dan Beck" <biscuitbecks@*nospam*cableone.net> wrote in message 
news:gagld5$erd$1...@registered.motzarella.org...
> Hello all,
>
> years ago I was given a 10 MHz Heathkit oscilloscope.  Both channels work 
> fine, and I use it to probe circuit boards powered up on the workbench.  I 
> now own an old hobby car with the old fashioned plugs/points/capacitor 
> ignition.  Is there any way I could use the 'scope to observe the ignition 
> signals, and would there be any value to it, besides academic information?
>
> Thank you in advance for any and all thoughts!
>
> Regards,
> Dan
>

The LT back emf could spike as high as 600V (maybe even higher) if the scope 
is all tube you should be OK, but if it uses transistors in the Y amplifiers 
some caution might be wise. Study the spec for the x10 probe and if it isn't 
rated for that voltage then make a voltage divider yourself, here again you 
need to check the voltage rating of the resistors - if necessary make the 
dropper section of the divider out of a number of series resistors. 

"ian field" <g...@ntlworld.com> wrote in message 
news:UoVyk.685$1...@newsfe27.ams2...
>
> "Dan Beck" <biscuitbecks@*nospam*cableone.net> wrote in message 
> news:gagld5$erd$1...@registered.motzarella.org...
>> Hello all,
>>
>> years ago I was given a 10 MHz Heathkit oscilloscope.  Both channels 
>> work fine, and I use it to probe circuit boards powered up on the 
>> workbench.  I now own an old hobby car with the old fashioned 
>> plugs/points/capacitor ignition.  Is there any way I could use the 
>> 'scope to observe the ignition signals, and would there be any value to 
>> it, besides academic information?
>>
>> Thank you in advance for any and all thoughts!
>>
>> Regards,
>> Dan
>>
>
> The LT back emf could spike as high as 600V (maybe even higher) if the 
> scope is all tube you should be OK, but if it uses transistors in the Y 
> amplifiers some caution might be wise. Study the spec for the x10 probe 
> and if it isn't rated for that voltage then make a voltage divider 
> yourself, here again you need to check the voltage rating of the 
> resistors - if necessary make the dropper section of the divider out of a 
> number of series resistors.


It might be prudent to add a neon lamp or a TVS bidirectional zener type 
suppressor across the scope inputs. I'm not sure how fast a neon lamp 
triggers, but the type of suppressors used in telephone equipment should be 
pretty good, and rated about 60 volts.

Here are links:
http://www.onsemi.com/PowerSolutions/supportDoc.do?type=datasheets&category=824
http://www.rectron.com/data_sheets/1.5ke.pdf

Paul 

On Sep 13, 10:14=A0am, "Dan Beck" <biscuitbecks@*nospam*cableone.net>
wrote:
> Hello all,
>
> years ago I was given a 10 MHz Heathkit oscilloscope. =A0Both channels wo=
rk
> fine, and I use it to probe circuit boards powered up on the workbench. =
=A0I
> now own an old hobby car with the old fashioned plugs/points/capacitor
> ignition. =A0Is there any way I could use the 'scope to observe the ignit=
ion
> signals, and would there be any value to it, besides academic information=
?
>
> Thank you in advance for any and all thoughts!
>
> Regards,
> Dan

You could take this oscilliscope, and check the rate of transfer
during disconnect of the 12V btty.
This will show you when your wires are degrading.  And, might even
indicate moisture due to acidic influence, a common ailment.

On 2008-09-14, Paul E. Schoen <p...@smart.net> wrote:
> It might be prudent to add a neon lamp or a TVS bidirectional zener type 
> suppressor across the scope inputs. I'm not sure how fast a neon lamp 
> triggers, but the type of suppressors used in telephone equipment should be 
> pretty good, and rated about 60 volts.

at 60 they'd fire on the ring voltage.

Bye.
   Jasen

"Jasen Betts" <j...@xnet.co.nz> wrote in message news:gaip33$33q$3@gonzo...
> On 2008-09-14, Paul E. Schoen <p...@smart.net> wrote:
>> It might be prudent to add a neon lamp or a TVS bidirectional zener type
>> suppressor across the scope inputs. I'm not sure how fast a neon lamp
>> triggers, but the type of suppressors used in telephone equipment should 
>> be
>> pretty good, and rated about 60 volts.
>
> at 60 they'd fire on the ring voltage.
>
> Bye.
>   Jasen

Might not be so bad if the OP builds a scope lead breakout box to add the 
neon so it can be shunt connected between a x10 probe and the scope input. 

Dan Beck wrote:

> Hello all,
> 
> years ago I was given a 10 MHz Heathkit oscilloscope.  Both channels work 
> fine, and I use it to probe circuit boards powered up on the workbench.  I 
> now own an old hobby car with the old fashioned plugs/points/capacitor 
> ignition.  Is there any way I could use the 'scope to observe the ignition 
> signals, and would there be any value to it, besides academic information?
> 
> Thank you in advance for any and all thoughts!
> 
> Regards,
> Dan 
> 
> 
  If you're interested in the HV current Pulse, You can wrap a couple of
turns around a plug wire and load the output to a low value resistor. 
This will act as a current xformer and provide you a safe a low voltage
reference signal for your scope to monitor the current pulse at the 
electrode on the plug.
   They make engine scope probes to clamp on plug wires and in line taps
accessories.
    At work, we actually use an automotive HV inline coupling to monitor 
a signal via a scope on irradiation units.

    You could also consider using a HV probe for scopes. The one you 
would need could be expensive.



http://webpages.charter.net/jamie_5";