# How would you select an 'ignition coil' ?

#### dknguyen

##### Well-Known Member
A spool zilion turns would be perfect, I could insert the core of choice but... There is no access to connect to the winding start wire...
Get the store to respool it for you in a specific way.

Also, pretty sure in many spools the other end of the wire is in the middle

#### ChrisP58

##### Well-Known Member
If you wind something up yourself, you'll need to segment the the winding onto sections like chemelec showed in post #19.

Otherwise you'll get internal arcing.

#### chemelec

##### Well-Known Member
Winding a Coil.
Ideally it should be Potted in transformer Oil.
NEVER Operate a Car Coil WITHOUT A SPARK GAP OR A LOAD.

This Coil in Operation.

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#### Externet

##### Active Member
Nice!, chemelec. But have no winding equipment.
Only the secondary is what I would need. 2 pieces. About 10K turns.
Will canibalize generic ignition coils... Went to Autozone, O'rileys, Napa, mechanic shops and... surprise ! Not stocked any more unless fancy 'performance' 'racing' types at $50. Modern times just passed me. Fast. #### chemelec ##### Well-Known Member Nice!, chemelec. But have no winding equipment. Only the secondary is what I would need. 2 pieces. About 10K turns. Will canibalize generic ignition coils... Went to Autozone, O'rileys, Napa, mechanic shops and... surprise ! Not stocked any more unless fancy 'performance' 'racing' types at$50. Modern times just passed me. Fast.
10,000 Turns wouldn't do much for a HV Output.

Was that coil you took apart, OIL Filled?

There are many of these Older Car Coils on ebay.com.
Usually around \$15.00 Plus Shipping cost.
https://www.ebay.com/itm/UNIVERSAL-...hash=item1a10bc7819:m:mcIxVV9k2VC84b9bqRMpp1Q

I make my Bobbins on my Metal Lathe, and I also Wind the coils on it at a High Speed.
I have a Digital Counter on it, so I can accurately count the Turns.

Want to TALK, Send me your Phone Number.
The USA is a Free call for me.

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#### OlPhart

##### Member
I agree with buying a performance engine ignition coil.
I Guarantee that with the correct firing pulse circuit, it Ain't No 1200 Volts.
Maybe with a steady state sine wave, but I'm talking hard core shunted primary field collapse.
P.S. Do Not check it with body parts... it HURTS (BTDT 2 MT). <<<)))

#### chemelec

##### Well-Known Member
Olphart, He is NOT Using this as a Car Coil.
He will Take it Apart as he Only wants the High Voltage Winding, for NON-HV Purposes.

#### OlPhart

##### Member
WOW, did I misinterpret the intended purpose (or was it somewhat obtuse?).
I'm now clueless of intent, is it a Big choke?, magnetic field?
Since I don't get it, I'm Out... GFL <<<)))

#### chemelec

##### Well-Known Member
POST #6, Am building a differential gradiometer

He Just wants a LOT OF TURNS Of Small Wire.

#### OlPhart

##### Member
Ok, had to look that up "gradiometer" wasn't familiar with term. (kinda vague term to me...)
So, ignorance query -- is a wire coil as sensor better than So Many hall effect based field strength sensors?
Not being facetious, just "ignorant" Tnx <<<)))

P.S. Maybe the difference is an "averaging" aspect to a wire coil, that a hall would "micro measure"?

P.P.S. maybe a high voltage small relay coil ?

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#### chemelec

##### Well-Known Member
Ok, had to look that up "gradiometer" wasn't familiar with term. (kinda vague term to me...)
So, ignorance query -- is a wire coil as sensor better than So Many hall effect based field strength sensors?
Not being facetious, just "ignorant" Tnx <<<)))

P.S. Maybe the difference is an "averaging" aspect to a wire coil, that a hall would "micro measure"?

P.P.S. maybe a low voltage "large" contactor relay coil ?
There are Pros and Cons, Verses Hall Effect and using Coils.

He was asking me to wind him Two, 10,000 Turn Coils with 40 AWG Wire on 1/2 inch ID, PVC Pipe (20 CM Winding Length)
But they had to be IDENTICAL.
I told him I could come Close, But not really Absolutely IDENTICAL.

So he was going to buy two car coils and take them apart to try them.
I Seriously DOUBT they will be Identical.

#### OlPhart

##### Member
That and Good Luck cutting open an ignition coil and Not Destroying the primary winding (it's on the outside (IIRC)).

ARF... 40 AWG and an even distribution, across ~ 8 inches ?? A tip of My cap..

I suspect if OP Really described the application, a Much Better answer would be evident.

#### chemelec

##### Well-Known Member
I can Easily Wind the Coil with 40 AWG.
I have a Digital Turns counter on my Metal Lathe and can Come Very Close to Perfect layers.
(I Wound One Layer to see if I could do it.)
10,000 Turns Would work out to 5 Layers with a layer of paper between wire layers.

#### OlPhart

##### Member
Again, a Hat tip to you. I'm dubious dealing with <32 AWG stuff.
I have a turns counter on my lathe, it's the gauge I'd goof up on.

Oh well, if OP doesn't reveal nature of measurement needed, he'll get proportional results.
TFB... <<<)))

#### chemelec

##### Well-Known Member
Again, a Hat tip to you. I'm dubious dealing with <32 AWG stuff.
I have a turns counter on my lathe, it's the gauge I'd goof up on.

Oh well, if OP doesn't reveal nature of measurement needed, he'll get proportional results.
TFB... <<<)))
Look at My Picture on Post 23.
"Middle Picture wound with 40 AWG".
Slight Gap near Beginning and end, No Overlaps and Almost Perfect.

#### gary350

##### Well-Known Member
An ignition coil from an old vehicle like a 1968 Chevy truck will give you a 1/4" to 3/8" spark on 12 volts if you can adjust the Hz with a 555 timer to get maximum output. You can still get replacement ignition coils at Auto Zone and O'Reilly auto parts. These are not made for high RF efficiency drops off at about 5K.