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#Post#: 71521--------------------------------------------------
A simple CDI unit for Partner
By: chy_farm Date: April 29, 2016, 10:36 am
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Early last year an old Partner came to me with her CDI unit
broken, she was R417T manufactured from 1974 according to Mike's
site.
(HTM) http://www.acresinternet.com/cscc.nsf/ed1d619968136da688256af40002b8f7/9eda198b7f2281e588256afd004bb92e?OpenDocument
(Mike's site shows her displacement as 85cc but it's not
correct, may be 55cc. )
Here showing videos of first experiment, some modification to
the capacitor, and the last one with a small and simple circuit
for this homemade CDI.
1:
(HTM) https://www.youtube.com/watch?v=QOu8ocmSQY8
2:
(HTM) https://www.youtube.com/watch?v=m25HGBV9trw
3:
(HTM) https://www.youtube.com/watch?v=6XSMr7vu3yo
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Chy
#Post#: 71554--------------------------------------------------
Re: A simple CDI unit for Partner
By: chy_farm Date: April 30, 2016, 5:21 pm
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Here showing a segment from IPL below.
She has two coils,
one for
a) pulser coil and exciter coil
the other for
b) primary coil and secondary coil.
#Post#: 71555--------------------------------------------------
Re: A simple CDI unit for Partner
By: chy_farm Date: April 30, 2016, 5:28 pm
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And a schematic here;
A couple of pink stuffs in the schematic is oscillo proves, not
the parts of the circuit.
#Post#: 71559--------------------------------------------------
Re: A simple CDI unit for Partner
By: chy_farm Date: April 30, 2016, 8:16 pm
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Here it is the circuit for it.
This circuit sits under the flywheel cover.
#Post#: 71583--------------------------------------------------
Re: A simple CDI unit for Partner
By: sharkey Date: May 1, 2016, 6:53 pm
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WOW. Good Job! Can you tell us how to get rid of the limiters
on the cdi's used on these newer saw engines? They usually
start to drop spark around 12,500 rpm and make it really tough
to tune.
#Post#: 71595--------------------------------------------------
Re: A simple CDI unit for Partner
By: chy_farm Date: May 2, 2016, 6:45 am
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Hello Sharkey, thank you for visiting and leaving a nice and
interesting tip, but I did not know things about limiters on
today's saws. My saws are mostly very old except for Husky
550XP.
Do you have a schematic of these limiters?
#Post#: 71637--------------------------------------------------
Re: A simple CDI unit for Partner
By: chy_farm Date: May 4, 2016, 8:43 am
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>I did not know things about limiters on today's saws. My saws
are mostly very old except for Husky 550XP.
>Do you have a schematic of these limiters?
Doesn't any body have better information about this schematic?
Chy
#Post#: 71638--------------------------------------------------
Re: A simple CDI unit for Partner
By: 3000 FPS Date: May 4, 2016, 10:03 am
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Ok very nice and good work.
I have a few questions. First the pink on the schematic is
that for the Oscilloscope probes.
Second does the 1 microfarad capacitor have a faster discharge
time over the 2.2 microfarad cap and hence affecting the
timing.
You might want to coat all your components in epoxy to protect
them from moisture and oil.
Could you go to a larger working voltage on the capacitor to
prevent it from getting to hot when making long cuts.
Also did you wind the pulser coil your self.
How high in the RPM's will this circuit be good for. Like say
up to 14,000 or more.
Some great info and is good to know you can always come up with
an ignition for an old saw.
#Post#: 71639--------------------------------------------------
Re: A simple CDI unit for Partner
By: 3000 FPS Date: May 4, 2016, 10:14 am
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I do not know of any schematics for ignitions that have limiting
coils. Besides those coils are all incased with epoxy and I
doubt that you could get into one to modify it in any way.
If you could get into one of the newer limiting coils and since
these ignition systems are solid state devices there is probably
a component in there that could be changed so that the RPM range
could be made to go higher.
#Post#: 71641--------------------------------------------------
Re: A simple CDI unit for Partner
By: 3000 FPS Date: May 4, 2016, 10:21 am
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I also noticed that in your first schematic at the end of your
video you use a SCR to discharge the capacitor into the ignition
coil.
On your second schematic you use two transistors to discharge
the capacitor into the ignition coil.
Just two different ways to do the same thing or is there a
reason that one is preferred over the other due to reliability
or something else.
Also the first one looks to be much more simple in design than
the second one.
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