Want to build a HEI ignition module similar to 70's style

default · Sep 23, 2008

Does anyone have a schematic for a simple four pin HEI ignition module
from 1970's+ ignition systems. They appear to contain an SCR and a
pair of diodes and resistors.

Pickup Coil connects to two terminals and battery and induction coil
primary the other two, mounting screw provides a ground connection.

Original type mounted to the distributor plate on GM cars and others
and was ~1/4 round shape - I want to adapt it to a motorcycle that has
pickup coils mounted remote from the modules.
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Ross Herbert · Sep 24, 2008

On Tue, 23 Sep 2008 15:26:42 -0400, default <default@defaulter.net> wrote:

oes anyone have a schematic for a simple four pin HEI ignition module
:from 1970's+ ignition systems. They appear to contain an SCR and a

air of diodes and resistors.
:

ickup Coil connects to two terminals and battery and induction coil

rimary the other two, mounting screw provides a ground connection.
:
:Original type mounted to the distributor plate on GM cars and others
:and was ~1/4 round shape - I want to adapt it to a motorcycle that has

ickup coils mounted remote from the modules.

Most 70's era street bikes would run from the 12V battery supply so you would
have to buy a kit suitable for this power supply. I don't know where you are but
here is one kit http://www.jaycar.com.au/productView.asp?ID=KC5442

If your bike doesn't have a battery which is chaarged from an
alternator/generator then it will probably use an generator supply winding to
produce the input voltage. In this case a simpler kit can be used
http://www.jaycar.com.au/productView.asp?ID=KC5466

default · Sep 24, 2008

On Wed, 24 Sep 2008 11:15:34 GMT, Ross Herbert
<rherber1@bigpond.net.au> wrote:

On Tue, 23 Sep 2008 15:26:42 -0400, default <default@defaulter.net> wrote:

oes anyone have a schematic for a simple four pin HEI ignition module
:from 1970's+ ignition systems. They appear to contain an SCR and a
air of diodes and resistors.
:
ickup Coil connects to two terminals and battery and induction coil
rimary the other two, mounting screw provides a ground connection.
:
:Original type mounted to the distributor plate on GM cars and others
:and was ~1/4 round shape - I want to adapt it to a motorcycle that has
ickup coils mounted remote from the modules.

Most 70's era street bikes would run from the 12V battery supply so you would
have to buy a kit suitable for this power supply. I don't know where you are but
here is one kit http://www.jaycar.com.au/productView.asp?ID=KC5442

The bike is 80's runs from the battery. They call it a CDI but it
isn't - runs from 12V with no HT generator coil - the module just has
4-5 components in it (potted in black goo) induction coil is ~3.5
ohms.

The advance is managed in the pickup coil end of things.

The dealer wants $200 per module and I need two for a bike worth
~$1,000. The 70's style module for cars runs about $40 now (was $15)
each.

If your bike doesn't have a battery which is chaarged from an
alternator/generator then it will probably use an generator supply winding to
produce the input voltage. In this case a simpler kit can be used
http://www.jaycar.com.au/productView.asp?ID=KC5466

Physically too large even if it was suitable. The originals are only
one cubic inch with mostly heat sink.

turned this up in my searching
http://members.aol.com/pullingtractor/ignition.htm
Interesting site with lots of DIY mods for small gas engines.
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Jim Thompson · Sep 24, 2008

On Wed, 24 Sep 2008 08:18:24 -0400, default <default@defaulter.net>
wrote:

On Wed, 24 Sep 2008 11:15:34 GMT, Ross Herbert
rherber1@bigpond.net.au> wrote:

On Tue, 23 Sep 2008 15:26:42 -0400, default <default@defaulter.net> wrote:

oes anyone have a schematic for a simple four pin HEI ignition module
:from 1970's+ ignition systems. They appear to contain an SCR and a
air of diodes and resistors.
:
ickup Coil connects to two terminals and battery and induction coil
rimary the other two, mounting screw provides a ground connection.
:
:Original type mounted to the distributor plate on GM cars and others
:and was ~1/4 round shape - I want to adapt it to a motorcycle that has
ickup coils mounted remote from the modules.

Most 70's era street bikes would run from the 12V battery supply so you would
have to buy a kit suitable for this power supply. I don't know where you are but
here is one kit http://www.jaycar.com.au/productView.asp?ID=KC5442

The bike is 80's runs from the battery. They call it a CDI but it
isn't - runs from 12V with no HT generator coil - the module just has
4-5 components in it (potted in black goo) induction coil is ~3.5
ohms.

[snip]

default · Sep 24, 2008

On Wed, 24 Sep 2008 07:45:10 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

Doesn't take much to make a CD Ignition, see....

http://analog-innovations.com/SED/CD-Ignition-Basic.pdf

Thanks. What is the theory of operation? What I have now, connects
one side of the coil to the battery and the other side to the ignition
module. In that circuit, D3 D2 would stay forward biased if the coil
goes to B+.

This circuit is supposed to dump a largish negative spike to the coil?

What kind of voltage does the transistor have to stand off?
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DaveM · Sep 25, 2008

Life is like a roll of toilet paper; the closer it gets to the end, the faster
it goes.

"Ross Herbert" <rherber1@bigpond.net.au> wrote in message
news:ls7kd410gaot8mdvsoletbfnde962i7j7h@4ax.com...

On Tue, 23 Sep 2008 15:26:42 -0400, default <default@defaulter.net> wrote:

oes anyone have a schematic for a simple four pin HEI ignition module
:from 1970's+ ignition systems. They appear to contain an SCR and a
air of diodes and resistors.
:
ickup Coil connects to two terminals and battery and induction coil
rimary the other two, mounting screw provides a ground connection.
:
:Original type mounted to the distributor plate on GM cars and others
:and was ~1/4 round shape - I want to adapt it to a motorcycle that has
ickup coils mounted remote from the modules.

Most 70's era street bikes would run from the 12V battery supply so you would
have to buy a kit suitable for this power supply. I don't know where you are
but
here is one kit http://www.jaycar.com.au/productView.asp?ID=KC5442

If your bike doesn't have a battery which is chaarged from an
alternator/generator then it will probably use an generator supply winding to
produce the input voltage. In this case a simpler kit can be used
http://www.jaycar.com.au/productView.asp?ID=KC5466

Here's a link to the Delta Mark 10 CDI.
http://www.selectric.org/delta/index.html
I used to have a couple of these units back in the day... sure saved points and
plugs after I installed them. Never had a moment's trouble from either of
them... built both from kits.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Jim Thompson · Sep 25, 2008

On Wed, 24 Sep 2008 14:36:05 -0400, default <default@defaulter.net>
wrote:

On Wed, 24 Sep 2008 07:45:10 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

[snip]

Doesn't take much to make a CD Ignition, see....

http://analog-innovations.com/SED/CD-Ignition-Basic.pdf

Thanks. What is the theory of operation?

All of the control circuitry is not shown.

(1) Transistor turns on
(2) When current in inductor reaches 5A, transistor turns off, dumping
energy into capacitor (~350V)
(3) When transistor turns on again, capacitor dumps into ignition coil
(conventional ratio) firing plug; and inductor charging begins again.

Works great... I've used it to saw Plexiglas ;-)

What I have now, connects
one side of the coil to the battery and the other side to the ignition
module. In that circuit, D3 D2 would stay forward biased if the coil
goes to B+.

This circuit is supposed to dump a largish negative spike to the coil?

What kind of voltage does the transistor have to stand off?

Tim Williams · Sep 25, 2008

On Sep 24, 1:36 pm, default <defa...@defaulter.net> wrote:

On Wed, 24 Sep 2008 07:45:10 -0700, Jim Thompson

To-Email-Use-The-Envelope-I...@My-Web-Site.com> wrote:
[snip]

Doesn't take much to make a CD Ignition, see....

http://analog-innovations.com/SED/CD-Ignition-Basic.pdf

Thanks. What is the theory of operation?

Let's see, Q1 charges L1 thru D1, then when Q1 lets go, L1 charges C1
through D1 and D2. After a quarter sine wave, current reverses and
the diodes drop out, leaving C1 more or less charged inbetween
cycles. (Without D1, L1+C1 could oscillate, the current being carried
through D2 and D3; D1 produces a clean break after exactly a quarter
wave.) This puts a considerable voltage on Q1, something like, let's
see, 5A in 5mH is 62.5mJ so... about 353V. When the transistor turns
on again, C1 is discharged through D3 and the ignition coil, so it
will need to handle whatever the peak current is (Ice > 10A), and the
peak voltage (Vceo > 400V).

If possible, a 2ms one-shot should be used to charge the inductor,
since V = L * dI/dt --> 12V = 5mH * 5A/2ms. This circuit can repeat
as soon as the inductor is done whipping around, which takes about 0.1
ms.

The lynch pin of this circuit is the transistor, which must be quite
beefy. If nothing else, a stout base drive must be provided, which I
suppose isn't hard to do in an automotive environment. hFE = 5, if
not 3 or 2, is probably the kind of drive needed for a relatively high
Vce, ampy transistor in deep saturation. (Incidentially, t_stg will
probably end up something absurd like, 5us, 10us if you don't pull as
much current out of the base- but this delay isn't at all critical, as
long as t_f is reasonable, it won't burn up much switching power.
It's switching at audio frequencies after all.)

This circuit is supposed to dump a largish negative spike to the coil?

Yup!

Tim

default · Sep 25, 2008

On Wed, 24 Sep 2008 18:03:28 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

Doesn't take much to make a CD Ignition, see....

http://analog-innovations.com/SED/CD-Ignition-Basic.pdf

Thanks. What is the theory of operation?

All of the control circuitry is not shown.

(1) Transistor turns on
(2) When current in inductor reaches 5A, transistor turns off, dumping
energy into capacitor (~350V)
(3) When transistor turns on again, capacitor dumps into ignition coil
(conventional ratio) firing plug; and inductor charging begins again.

Works great... I've used it to saw Plexiglas ;-)

What I have now, connects
one side of the coil to the battery and the other side to the ignition
module. In that circuit, D3 D2 would stay forward biased if the coil
goes to B+.

This circuit is supposed to dump a largish negative spike to the coil?

What kind of voltage does the transistor have to stand off?

I used 500V BVCEO (NPN) devices.

There are probably Power MOSFET's now that would work better... HV
NPN's have lousy beta, requiring beta correction circuits in the
current sensing.

...Jim Thompson
Thanks, I'll give it a try.

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default · Sep 25, 2008

On Wed, 24 Sep 2008 20:50:46 -0400, "DaveM"
<masondg4499@comcast99.net> wrote:

Here's a link to the Delta Mark 10 CDI.
http://www.selectric.org/delta/index.html
I used to have a couple of these units back in the day... sure saved points and
plugs after I installed them. Never had a moment's trouble from either of
them... built both from kits.

--
Thanks. This isn't something I can use on this bike - too large. I

did build two of these myself in the 70's one went on a BMW motorcycle
and the other a Land Cruiser.

I think Jim's circuit is more viable given the components we have
today - and my size constraints. (although I could run one inverter
to boost voltage for both spark coils then just double up the SCR cap
circuits).

Appreciate the feedback, and I'll save the schematic
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Jim Thompson · Sep 25, 2008

On Thu, 25 Sep 2008 09:08:09 -0400, default <default@defaulter.net>
wrote:

On Wed, 24 Sep 2008 18:03:28 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

Doesn't take much to make a CD Ignition, see....

http://analog-innovations.com/SED/CD-Ignition-Basic.pdf

Thanks. What is the theory of operation?

All of the control circuitry is not shown.

(1) Transistor turns on
(2) When current in inductor reaches 5A, transistor turns off, dumping
energy into capacitor (~350V)
(3) When transistor turns on again, capacitor dumps into ignition coil
(conventional ratio) firing plug; and inductor charging begins again.

Works great... I've used it to saw Plexiglas ;-)

What I have now, connects
one side of the coil to the battery and the other side to the ignition
module. In that circuit, D3 D2 would stay forward biased if the coil
goes to B+.

This circuit is supposed to dump a largish negative spike to the coil?

What kind of voltage does the transistor have to stand off?

I used 500V BVCEO (NPN) devices.

There are probably Power MOSFET's now that would work better... HV
NPN's have lousy beta, requiring beta correction circuits in the
current sensing.

...Jim Thompson
Thanks, I'll give it a try.

default · Sep 25, 2008

On Thu, 25 Sep 2008 08:16:16 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

Thoughts coming back to me... with a conventional ignition coil (from
a car points-type system), peak primary current was 11 Amps! So size
your MOSFET accordingly.

Coil resistance is 3.5 ohms, that's only 4 amps.
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Jim Thompson · Sep 25, 2008

On Thu, 25 Sep 2008 12:08:22 -0400, default <default@defaulter.net>
wrote:

On Thu, 25 Sep 2008 08:16:16 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

Thoughts coming back to me... with a conventional ignition coil (from
a car points-type system), peak primary current was 11 Amps! So size
your MOSFET accordingly.

Coil resistance is 3.5 ohms, that's only 4 amps.

When hit with 350V ?

default · Sep 25, 2008

On Thu, 25 Sep 2008 09:23:10 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

On Thu, 25 Sep 2008 12:08:22 -0400, default <default@defaulter.net
wrote:

On Thu, 25 Sep 2008 08:16:16 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

Thoughts coming back to me... with a conventional ignition coil (from
a car points-type system), peak primary current was 11 Amps! So size
your MOSFET accordingly.

Coil resistance is 3.5 ohms, that's only 4 amps.

When hit with 350V ?

...Jim Thompson
Oh.

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Jim Thompson · Sep 25, 2008

On Thu, 25 Sep 2008 12:39:44 -0400, default <default@defaulter.net>
wrote:

On Thu, 25 Sep 2008 09:23:10 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

On Thu, 25 Sep 2008 12:08:22 -0400, default <default@defaulter.net
wrote:

On Thu, 25 Sep 2008 08:16:16 -0700, Jim Thompson
To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:

Thoughts coming back to me... with a conventional ignition coil (from
a car points-type system), peak primary current was 11 Amps! So size
your MOSFET accordingly.

Coil resistance is 3.5 ohms, that's only 4 amps.

When hit with 350V ?

...Jim Thompson
Oh.

Yep! You missed that the cap acquires charge when the inductor dumps

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