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# Electrical Specifications for Bosch Ignition Coil No. 0221119027

09/19/2017 6:09 AM

I am looking for this information which I could not find on internet or from company.

Electrical specifications for BOSCH ignition coil No. 0221119027. Key parameters I am looking for are Maximum input coil voltage and maximum input coil current Minimum and maximum pulse width required for coil and maximum repeat rate Output voltage and current ratio with respect to input voltage and current

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#1

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/19/2017 6:19 AM

It looks like the input voltage is a nominal 12VDC, from what it says on the tin. The current will be this divided by its resistance across the primary terminals, which will be found from measurement.

Surely the maximum repeat rate will be in excess of the maximum speed of the engine to which it is attached multiplied by its number of cylinders? This will also determine the maximum pulse width, for if the engine turns any faster than that, the coil won't do its job.

The width of the pulse depends upon the rate of rise and collapse of the magnetic field in the primary windings, which are functions of external circuits and components.

Perhaps that's why the specification called for cannot be found?

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#2

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/19/2017 6:41 AM

Hi PWSlack:

These coils are usually fired at 12V and for 0.1ms to 1ms. Coil resistance is about 0.5 ohms and that means 24A peak current may flow consuming peak power of V*I=288W. Considering. Perhaps if I fire it with small pulses, it may not burn.

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#6

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/19/2017 3:08 PM

Current would depend on inductance L as well as resistance R.

V = R*I + L*dI/dt

Neglecting resistance for the moment, current would ramp up at rate V/L.

(Figuring in resistance, the "ramp" would be the beginning of an exponential curve converging on I=V/R.)

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#16

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/20/2017 5:04 PM

Yes, the rise time is expected of 100us. My concern is open circuit voltage which is expected to be about 20kV and the peak current in open air discharge in 3mm-5mm dry air spark gap.

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#8

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/19/2017 7:01 PM

What does BOSCH International say about it?

It looks to be an older-style inductive-ignition spark plug coil, which may be out of production.

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#12

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/20/2017 10:05 AM

It looks like the same coil I had on my 1967 type ll.

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#9

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/19/2017 9:42 PM

The optimum pulse width, or dwell time, decreases with battery voltage. The optimum is when the magnetic field in the coil core reaches saturation. Any more just increases heat generation and less means less spark voltage. Many coils have tables or plots of battery voltage versus dwell time. (I have not found a table for your particular coil. You might want to contact Bosch and request that information.)

https://spdispark.com/pages/frequently-asked-questions-dwell.html#Q: How Can I Determine How Much Dwell Time My Coil Needs?

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#17

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/20/2017 5:07 PM

That sounds very reasonable.

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#11

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/20/2017 3:38 AM

0.5ohm seems way too low if it's an ordinary ignition coil. In the old days of simple coil + contact breaker ignition if you just switched on the ignition, current was more like 3-4amp than 24. And that's steady state, so inductive effects don't come into it.

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#22

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/21/2017 4:06 AM

If it is 3-4A steady state current then resistance has to be 3-4 ohms which is not in this coil. Maximum primary coil resistance reported by a friend is 0.75 ohms. I am not sure if heated coil has greater resistance for some reason. However, it may be possible. Inrush current 16A itself looks on high side.

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#23

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/21/2017 6:12 AM

I just checked the resistance of a coil I’ve had kicking about for 35-odd years. It’s a Motorcraft (Ford) coil, from a nominal 12volt car, but it was fed via a resistor which dropped the voltage when running. The resistor was bypassed during cranking, via an extra contact on the starter motor, to give higher voltage at the coil, better spark, easier starting.

Measured resistance is 1.4ohm. I don’t know running voltage, it’s not stamped on the coil, but assuming 6volt (Ford may have had some 6volt coils going spare from 6volt car days!) that gives 4.3amp, much in line with what I would expect. I’m talking about a cold coil, just switching on first thing. The ammeter typically went to +/- 30amp, so not possible to read 3-4 amp accurately, but it wasn’t 24amp. My guess is average current when running is much lower, as the contact breaker is only closed part of the time.

If current 16A itself looks on high side, 24amp looks worse. Was your friend’s coil a regular 12volt, or maybe like mine? Still comes to ~ 8amp, but getting more reasonable.

Why would there be a high inrush current? With the self-inductance, I’d expect current to ramp up to steady state. Heated coil has greater resistance, a filament-type light bulb has inrush several times running current, but a coil doesn’t get all that hot, and it takes a while to warm up.

Maybe coils designed for CD systems (if that’s what yours is) are different.

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#24

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/21/2017 8:54 AM

That is a great amount of information. Thank you.

I am in UK right now and in first week of October I will be back in India and then I can verify the details by recording in oscilloscope. Catalogs don't even show proper details. I did find details for some high voltage coils and perhaps they are for race cars with huge voltage and current.

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#26

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/21/2017 12:41 PM

A little bit of info that might help. From Jan 1970 "Wireless World" electronic ignition article. Welcome to UK! The "energy requirements" are stored energy in coil or capacitor - rather than what reaches the spark gap. For gas turbine ignition, only 1/4 of capacitor stored energy reaches plug - about 1/4 remains in capacitor, rest disappears in resistance.

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#30

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/22/2017 12:38 PM

Thanks for information.

I think this magazine "Wireless World" was Reed Publication and there was some extra name to it. I published few articles in it 25 years ago. I also won editor's prize. I think they were paying 100 pounds for normal idea and double for selected editor's best.

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#31

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/22/2017 1:26 PM

Many years ago, when I was a lad in middle school, as I recall, there was an assembly at my school, and the presenters were two, maybe it was three gentlemen from India, and although I cannot remember their names, it seems I can remember their faces, and one of them I think was part of my inspiration for going into science later on.

So thank you whomever you are, for that.

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#32

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/22/2017 4:20 PM

That is graceful. Thanks.

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#29

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/21/2017 6:38 PM

http://www.st.com/en/applications/automotive-and-transportation.html

Search for "ignition" - application notes for "car ignition with igbts" & "Capacitive Discharge Ignition AN819"

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#36

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/30/2017 11:21 AM

If you're still interested, I got access to a standard Lucas 12 volt coil (also very old), and checked resistance. It was 3 - 3.5 ohm, which tallies pretty well with the figure in #23 (if the assumption about 6 volt normal operating voltage is correct)

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#5

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/19/2017 3:02 PM

Surely the maximum repeat rate will be in excess of the maximum speed of the engine to which it is attached multiplied by its number of cylinders? If 4 stroke cycle, number of cylinders divided by 2.

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#14

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/20/2017 11:33 AM

Thanks!

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#18

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/20/2017 5:09 PM

It is electronic fired for testing right now but yes, whatever you have stated is true.

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#3

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/19/2017 12:17 PM

No joy.

Here's the

 OEM Part Number 043905115C
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#4

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/19/2017 1:42 PM

The time constant involved in any Bode plot on the input side of this device is determined by the equivalent tank circuit, correct? Just as a capacitor (a so-called pure one) when combined with a resistor will exhibit a well-defined time constant of decaying voltage across said resistor, so will the current across the resistor decay when placed in a circuit (with minimal capacitance) with an inductor, according to the known laws of voltage and current. In this case, it may be somewhat complicated by the existence of the secondary winding, of many many turns, and whatever feedback it presents to the decaying field of the primary coil.

Why not just connect the bad boy up to a signal generator, and look at the attenuated output on a scope? You should be able to sweep frequency, and get the roll off of the ignition coil, and then determine the practical maximum frequency of pulsation.

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#7

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/19/2017 3:45 PM

You likely won't get any specification details on this as these ignition coils are built for a specific purpose only and datasheets are kept as proprietary information by the manufacturers. If you want to use it for another purpose other than an internal combustion engine then it is totally on the user to figure it out.

Your best bet is to buy a few and either test them to destruction or try to test and model the output to get a vague idea of their characteristics (you will need to use an oscilloscope to monitor the waveform shape in either case). Fortunately they are fairly inexpensive so it won't matter if you destroy a few finding out what they can handle.

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#10

### Re: Electrical specifications for BOSCH ignition coil No. 0221119027

09/19/2017 9:52 PM

The coil is for a 67-79 VW 4 cyl engine. You can find more info here and here. Check the schematic of the ignition for that engine and make sure to include the ballast resistor in your calculations. You may also want to try measuring the parameters using an old distributor run by a variable speed motor, plus adjusting the points for gap/dwell time to see how the pulse width affects the output voltage.

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#13

### Re: Electrical Specifications for BOSCH ignition coil No. 0221119027

09/20/2017 11:27 AM

It looks like a contact breaker fed ignition coil of 1960s vintage. I fed a similar coil, Lucas LA12 from capacitor discharge electronics in 1970s. Nominal capacitor voltage of 400 was 800 for starting & idle (with choke in!). Pulse was "half sine", 100 microsecond wide spark on HV, 8 amp peak on primary and 0.16 amp on secondary - looks like 50:1. Spark gap of 1 cm - 2cm easily broke down: 20 to 40 kV.

As inductive discharge, Contact breaker fed, with CB capacitor, peak current was about 4.5 amp, L/R around 2 to 10 ms- I guess it depended on whether you had 4, 6, 8, 12 cylinders. Peak voltage LV about 300. Secondary rise time was about 125 microseconds. I think pulse length was less than 1 ms - 6000 rev/min, 4 cylinder is 5 ms between sparks.

I suggest you try 12V 50 Hz on SECONDARY and measure primary volts (nominal 12V) for ratio. Or use a house bell transfo - usually give 4/6V. You could get primary L/R from oscilloscope measure of primarycurrent.

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#15

### Re: Electrical Specifications for BOSCH ignition coil No. 0221119027

09/20/2017 5:00 PM

Yes, I am also expecting 5A peak current at 12V by limiting pulse width 1ms and repeat rate, average power can be brought down. 20kV is expected at the secondary at about 3mA peak current.

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#19

### Re: Electrical Specifications for BOSCH ignition coil No. 0221119027

09/20/2017 6:04 PM

Note that there would be no point in having longer pulse than 0.5 ms for 4 cyl (less for 6 cyl) since 36 degrees = 1/10 rev is maximum ignition advance before top dead centre of cylinder. HV rise-time is limited by leakage inductance and the capacitance of the HV winding, these coils were oil filled. I guess the brutal way to drive is rectified 230VAC transfo, large electrolytic reservoir [front end of PC computer PSU] and IGBJT. In 1970s, I used 1 microfarad capacitor for discharge and 10 ohm carbon resistor to measure HV current - the thyristor did not seem to be damaged by anode-cathode voltage breakdown triggering, I guess the leakage inductance stopped excessive gate current.

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#20

### Re: Electrical Specifications for BOSCH ignition coil No. 0221119027

09/20/2017 7:30 PM

Yes, lower pulse width is ideal. 0.05 ms to 0.5 ms looks like a good range to work on. MOSFET are faster and for current up to 30A easily available. IGBT can take much higher current and are robust for low frequency switching. IRF510 MOSFET looks alright to me

https://www.vishay.com/docs/91015/sihf510.pdf

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#25

### Re: Electrical Specifications for BOSCH ignition coil No. 0221119027

09/21/2017 9:59 AM

You should look into GaN transistors.

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#27

### Re: Electrical Specifications for BOSCH ignition coil No. 0221119027

09/21/2017 2:07 PM

May be I will use GaN for high frequency switching and high temperature applications.

At present I am using MOSFETs from IXYSRF USA.

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#28

### Re: Electrical Specifications for BOSCH ignition coil No. 0221119027

09/21/2017 2:14 PM

Salute! Good luck with project!

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#34

### Re: Electrical Specifications for BOSCH ignition coil No. 0221119027

09/24/2017 1:51 PM

Apologies for late read of your pdf. You have not actually written that your application is auto ignition, rather than a convenient HV pulse transfo. If it were ignition, since others have indicated your specified coil is about 0.5 ohm, an ON resistance of o.54 ohm seems inadequate, while a max drain voltage of 100 would limit to 5 to 10 kV at HV for ratio 50- 100 to one.

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#21

### Re: Electrical Specifications for BOSCH ignition coil No. 0221119027

09/21/2017 3:48 AM

OK but do you agree with my #11 about resistance? Maybe coils specifically designed for a CD system have lower resistance (I wouldn't know), but you could fit an add-on CD system to a standard coil. I did it in late 70s. I didn't notice any big improvement, possibly more reliable starting. Poor starting was a bit of a tradition back then. They don't make cars like that any more, thank God!

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#33

### Re: Electrical Specifications for Bosch Ignition Coil No. 0221119027

09/23/2017 7:43 AM

Keep in mind the "12 Volts" on the label is not necessarily reality depending on what you are doing with it. Most charging systems are regulated to approximately 14.4 Volts since this is required to fully charge a "12 Volt" automotive battery to it full charge of 12.6 Volts. (Fully charged the Shorai Lithium-Ion battery in my motorcycle measures 14.4 Volts).

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#35

### Re: Electrical Specifications for Bosch Ignition Coil No. 0221119027

09/25/2017 1:28 AM

Coil can handle much larger pulsed voltages and limited by pulse heat generated and not reaching melting point of wire or killing coil wire insulation.

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