Creating sparks with a mosfet and ignition coil

I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.

I found this 555 circuit online:
http://www.sci-experiments.com/HighVoltagePulser/

My questions:
(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?

(2) Does the 0.1 uF, 250V capacitor take the place of a Schottky snubber diode? Which is preferable?

(3) Would this circuit work properly for several hours, or would something (the coil, the mosfet) give up?

Thanks!

Michael

 

On Thursday, May 22, 2014 9:23:10 AM UTC-7, Jim Thompson wrote:

On Thu, 22 May 2014 09:02:00 -0700 (PDT), mrdarrett@gmail.com wrote:



I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.



I found this 555 circuit online:

http://www.sci-experiments.com/HighVoltagePulser/



My questions:

(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?



(2) Does the 0.1 uF, 250V capacitor take the place of a Schottky snubber diode? Which is preferable?



Change C4 to 1uF 100V, then use IRF530... should be OK.... no

warranties, express or implied ;-)

One microfarad! Huh. Ok!

(3) Would this circuit work properly for several hours, or would something (the coil, the mosfet) give up?



Thanks!



Michael



Hard to know, the circuit is a mess of uncontrol.

...Jim Thompson

Thanks!

Michael

 

On Thursday, May 22, 2014 9:57:21 AM UTC-7, Jim Thompson wrote:

On Thu, 22 May 2014 09:30:23 -0700 (PDT), mrdarrett@gmail.com wrote:



On Thursday, May 22, 2014 9:23:10 AM UTC-7, Jim Thompson wrote:

On Thu, 22 May 2014 09:02:00 -0700 (PDT), mrdarrett@gmail.com wrote:







I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.







I found this 555 circuit online:



http://www.sci-experiments.com/HighVoltagePulser/







My questions:



(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?







(2) Does the 0.1 uF, 250V capacitor take the place of a Schottky snubber diode? Which is preferable?







Change C4 to 1uF 100V, then use IRF530... should be OK.... no



warranties, express or implied ;-)





One microfarad! Huh. Ok!



A guess based on inductive energy, the original C4 value at 250V ;-)

Should I add a Schottky snubber diode in parallel with the primary coil, for extra MOSFET protection? Or would that interfere with the cap?

Thanks,

Michael

 

[Jim Thompson]

On Thu, 22 May 2014 09:02:00 -0700 (PDT), mrdarrett@gmail.com wrote:

I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.

I found this 555 circuit online:
http://www.sci-experiments.com/HighVoltagePulser/

My questions:
(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?

(2) Does the 0.1 uF, 250V capacitor take the place of a Schottky snubber diode? Which is preferable?

Change C4 to 1uF 100V, then use IRF530... should be OK.... no
warranties, express or implied ;-)

(3) Would this circuit work properly for several hours, or would something (the coil, the mosfet) give up?

Thanks!

Michael

Hard to know, the circuit is a mess of uncontrol.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jim Thompson]

On Thu, 22 May 2014 09:30:23 -0700 (PDT), mrdarrett@gmail.com wrote:

On Thursday, May 22, 2014 9:23:10 AM UTC-7, Jim Thompson wrote:
On Thu, 22 May 2014 09:02:00 -0700 (PDT), mrdarrett@gmail.com wrote:



I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.



I found this 555 circuit online:

http://www.sci-experiments.com/HighVoltagePulser/



My questions:

(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?



(2) Does the 0.1 uF, 250V capacitor take the place of a Schottky snubber diode? Which is preferable?



Change C4 to 1uF 100V, then use IRF530... should be OK.... no

warranties, express or implied ;-)


One microfarad! Huh. Ok!

A guess based on inductive energy, the original C4 value at 250V ;-)

(3) Would this circuit work properly for several hours, or would something (the coil, the mosfet) give up?



Thanks!



Michael



Hard to know, the circuit is a mess of uncontrol.

...Jim Thompson


Thanks!

Michael

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jim Thompson]

On Thu, 22 May 2014 10:15:17 -0700 (PDT), mrdarrett@gmail.com wrote:

On Thursday, May 22, 2014 9:57:21 AM UTC-7, Jim Thompson wrote:
On Thu, 22 May 2014 09:30:23 -0700 (PDT), mrdarrett@gmail.com wrote:



On Thursday, May 22, 2014 9:23:10 AM UTC-7, Jim Thompson wrote:

On Thu, 22 May 2014 09:02:00 -0700 (PDT), mrdarrett@gmail.com wrote:







I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.







I found this 555 circuit online:



http://www.sci-experiments.com/HighVoltagePulser/







My questions:



(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?







(2) Does the 0.1 uF, 250V capacitor take the place of a Schottky snubber diode? Which is preferable?







Change C4 to 1uF 100V, then use IRF530... should be OK.... no



warranties, express or implied ;-)





One microfarad! Huh. Ok!



A guess based on inductive energy, the original C4 value at 250V ;-)


Should I add a Schottky snubber diode in parallel with the primary coil, for extra MOSFET protection? Or would that interfere with the cap?

Thanks,

Michael

That will interfere with the energy transfer.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[o pere o]

On 05/22/2014 06:02 PM, mrdarrett@gmail.com wrote:

I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.

I found this 555 circuit online:
http://www.sci-experiments.com/HighVoltagePulser/

My questions:
(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?

(2) Does the 0.1 uF, 250V capacitor take the place of a Schottky snubber diode? Which is preferable?

(3) Would this circuit work properly for several hours, or would something (the coil, the mosfet) give up?

Thanks!

Michael

The link incorrectly states that "Energy flows back and forth resonantly
between the magnetic field in the coil and the electric field in the
capacitor, with a period given approximately by 2 pi x Sq. Rt. (LxC),
the energy decaying rapidly as energy is transferred to the secondary
side spark and to the wiring resistance."

This would certainly be the case if there was no spark at the secondary.
As soon as there is a spark you have to switch in a new circuit model
with a low resistance which rapidly absorbs the stored energy. So only
the first part (less than T/4) of a sinusoid is seen after switching.

Pere

 

On Thursday, May 22, 2014 3:39:13 PM UTC-7, Maynard A. Philbrook Jr. wrote:

In article <937da223-9089-4d09-9082-ff101fc48ba2@googlegroups.com>,

mrdarrett@gmail.com says...



I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.



I found this 555 circuit online:

http://www.sci-experiments.com/HighVoltagePulser/



My questions:

(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?

yes, it should be used for maximum effect!



(2) Does the 0.1 uF, 250V capacitor take the place of a Schottky snubber diode? Which is preferable?

It's a controlled release. In other words, it does not completely clamp

the voltage, which is why you need a High Voltage fet.



(3) Would this circuit work properly for several hours, or would something (the coil, the mosfet) give up?



Should work just fine.



Thanks!



Michael





Jamie

Okie doke! Thanks!

Michael

 

[Maynard A. Philbrook Jr.]

In article <937da223-9089-4d09-9082-ff101fc48ba2@googlegroups.com>,
mrdarrett@gmail.com says...

I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.

I found this 555 circuit online:
http://www.sci-experiments.com/HighVoltagePulser/

My questions:
(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?
yes, it should be used for maximum effect!

(2) Does the 0.1 uF, 250V capacitor take the place of a Schottky snubber diode? Which is preferable?

It's a controlled release. In other words, it does not completely clamp
the voltage, which is why you need a High Voltage fet.

(3) Would this circuit work properly for several hours, or would something (the coil, the mosfet) give up?

Should work just fine.

Thanks!

Michael

Jamie

 

[Bob Masta]

On Thu, 22 May 2014 09:02:00 -0700 (PDT),
mrdarrett@gmail.com wrote:

I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.

I found this 555 circuit online:
http://www.sci-experiments.com/HighVoltagePulser/

My questions:
(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?

Back in the day (late '60s, early '70s) when I worked for
the auto industry, the voltage across the breaker points in
the primary of a mechanical-type system could easily go over
300V. I don't recall checking the equivalent in the
electronically-switched types, but they did put out a lot
more secondary volts. So you probably ought to stick with
the 500V part.

Best regards,



Bob Masta

DAQARTA v7.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, Pitch Track, Pitch-to-MIDI
FREE Signal Generator, DaqMusiq generator
Science with your sound card!

 

On Friday, May 23, 2014 4:59:58 AM UTC-7, Bob Masta wrote:

On Thu, 22 May 2014 09:02:00 -0700 (PDT),

mrdarrett@gmail.com wrote:



I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.



I found this 555 circuit online:

http://www.sci-experiments.com/HighVoltagePulser/



My questions:

(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?



Back in the day (late '60s, early '70s) when I worked for

the auto industry, the voltage across the breaker points in

the primary of a mechanical-type system could easily go over

300V. I don't recall checking the equivalent in the

electronically-switched types, but they did put out a lot

more secondary volts. So you probably ought to stick with

the 500V part.



Best regards,







Bob Masta

Ok, I will! It's time to place another order with Mouser anyway...

Thanks!

Michael

 

[Jim Thompson]

On Fri, 23 May 2014 09:10:55 -0700 (PDT), mrdarrett@gmail.com wrote:

On Friday, May 23, 2014 4:59:58 AM UTC-7, Bob Masta wrote:
On Thu, 22 May 2014 09:02:00 -0700 (PDT),

mrdarrett@gmail.com wrote:



I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.



I found this 555 circuit online:

http://www.sci-experiments.com/HighVoltagePulser/



My questions:

(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?



Back in the day (late '60s, early '70s) when I worked for

the auto industry, the voltage across the breaker points in

the primary of a mechanical-type system could easily go over

300V. I don't recall checking the equivalent in the

electronically-switched types, but they did put out a lot

more secondary volts. So you probably ought to stick with

the 500V part.



Best regards,







Bob Masta


Ok, I will! It's time to place another order with Mouser anyway...

Thanks!

Michael

The voltage across the points (_and_ the effective spark voltage) is a
function of the value of the capacitor across the points.

Here's my basic self-inverting CD ignition from the 1968-1973 time
frame...

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

<http://www.analog-innovations.com/SED/CDI_Inductor.jpg>

when I was designing chips for Ford, GM, Chrysler, and American
Motors... you do remember American Motors don't you ?:-} (Mitt
Romney's father, George W. Romney.)

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

Bipolar transistor? Why?

 

[Jim Thompson]

On Sat, 24 May 2014 00:48:18 -0700 (PDT), mrdarrett@gmail.com wrote:

>Bipolar transistor? Why?

Power/DMOS MOSFET's didn't exist in 1970.

To further complicate matters, the HV NPN's of the day had lousy beta,
as in ~3 at IC=5.5A

So the tricky part, not shown, was how I developed a chip to calculate
IC from IE measured at ground, to get the current trip point to stay
right at 5.5A irrespective of temperature.

With today's Power MOSFET's it's a trivial task.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

#BringBackOurBalls

 

On Friday, May 23, 2014 9:20:43 AM UTC-7, Jim Thompson wrote:

On Fri, 23 May 2014 09:10:55 -0700 (PDT), mrdarrett@gmail.com wrote:



On Friday, May 23, 2014 4:59:58 AM UTC-7, Bob Masta wrote:

On Thu, 22 May 2014 09:02:00 -0700 (PDT),



mrdarrett@gmail.com wrote:







I would like to generate a series of ~1000 volt sparks continuously, for several hours, using a spare automotive ignition coil I have lying around.







I found this 555 circuit online:



http://www.sci-experiments.com/HighVoltagePulser/







My questions:



(1) Is a 500-volt MOSFET really necessary? Would a 100-volt IRF530 work alright without frying?







Back in the day (late '60s, early '70s) when I worked for



the auto industry, the voltage across the breaker points in



the primary of a mechanical-type system could easily go over



300V. I don't recall checking the equivalent in the



electronically-switched types, but they did put out a lot



more secondary volts. So you probably ought to stick with



the 500V part.







Best regards,















Bob Masta





Ok, I will! It's time to place another order with Mouser anyway...



Thanks!



Michael



The voltage across the points (_and_ the effective spark voltage) is a

function of the value of the capacitor across the points.

I have a dual 60+10 uF, 440V capacitor I salvaged from the AC unit after installing a new cap. Would this work alright?

I finally have some spare time and maybe I can build this with parts I have lying around (irf530, dual cap, etc.)

Could you give the equations which would dictate the voltage across the spark gap and the voltage across the mosfet, as a function of capacitance?

Thanks!

Michael

 

On Friday, July 4, 2014 11:13:54 AM UTC-7, Jim Thompson wrote:

On Fri, 4 Jul 2014 11:02:43 -0700 (PDT), mrdarrett@gmail.com wrote:



On Friday, May 23, 2014 9:20:43 AM UTC-7, Jim Thompson wrote:

On Fri, 23 May 2014 09:10:55 -0700 (PDT), mrdarrett@gmail.com wrote:



[snip]





The voltage across the points (_and_ the effective spark voltage) is a



function of the value of the capacitor across the points.





I have a dual 60+10 uF, 440V capacitor I salvaged from the AC unit after installing a new cap. Would this work alright?



I finally have some spare time and maybe I can build this with parts I have lying around (irf530, dual cap, etc.)



Could you give the equations which would dictate the voltage across the spark gap and the voltage across the mosfet, as a function of capacitance?



Thanks!



Michael



For a typical automotive coil (from a point type ignition), ~1uF is

the proper value... NON-electrolytic.



L*I^2 = C*V^2 dominates until the secondary "sparks"



And you need to time shut-off based on coil current.



I ought to write that up one of these days ;-)



...Jim Thompson

L*I^2 = C*V^2... V is Vds across the mosfet, right? So, the greater the C, the lower the V (which keeps my mosfet from frying), right?

 

[Jim Thompson]

On Fri, 4 Jul 2014 11:02:43 -0700 (PDT), mrdarrett@gmail.com wrote:

On Friday, May 23, 2014 9:20:43 AM UTC-7, Jim Thompson wrote:
On Fri, 23 May 2014 09:10:55 -0700 (PDT), mrdarrett@gmail.com wrote:

[snip]


The voltage across the points (_and_ the effective spark voltage) is a

function of the value of the capacitor across the points.


I have a dual 60+10 uF, 440V capacitor I salvaged from the AC unit after installing a new cap. Would this work alright?

I finally have some spare time and maybe I can build this with parts I have lying around (irf530, dual cap, etc.)

Could you give the equations which would dictate the voltage across the spark gap and the voltage across the mosfet, as a function of capacitance?

Thanks!

Michael

For a typical automotive coil (from a point type ignition), ~1uF is
the proper value... NON-electrolytic.

L*I^2 = C*V^2 dominates until the secondary "sparks"

And you need to time shut-off based on coil current.

I ought to write that up one of these days ;-)

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jim Thompson]

On Fri, 4 Jul 2014 11:35:01 -0700 (PDT), mrdarrett@gmail.com wrote:

On Friday, July 4, 2014 11:13:54 AM UTC-7, Jim Thompson wrote:
On Fri, 4 Jul 2014 11:02:43 -0700 (PDT), mrdarrett@gmail.com wrote:



On Friday, May 23, 2014 9:20:43 AM UTC-7, Jim Thompson wrote:

On Fri, 23 May 2014 09:10:55 -0700 (PDT), mrdarrett@gmail.com wrote:



[snip]





The voltage across the points (_and_ the effective spark voltage) is a



function of the value of the capacitor across the points.





I have a dual 60+10 uF, 440V capacitor I salvaged from the AC unit after installing a new cap. Would this work alright?



I finally have some spare time and maybe I can build this with parts I have lying around (irf530, dual cap, etc.)



Could you give the equations which would dictate the voltage across the spark gap and the voltage across the mosfet, as a function of capacitance?



Thanks!



Michael



For a typical automotive coil (from a point type ignition), ~1uF is

the proper value... NON-electrolytic.



L*I^2 = C*V^2 dominates until the secondary "sparks"



And you need to time shut-off based on coil current.



I ought to write that up one of these days ;-)



...Jim Thompson


L*I^2 = C*V^2... V is Vds across the mosfet, right? So, the greater the C, the lower the V (which keeps my mosfet from frying), right?

Correct, And also limits the spark voltage.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

On Friday, July 4, 2014 11:46:32 AM UTC-7, Jim Thompson wrote:

On Fri, 4 Jul 2014 11:35:01 -0700 (PDT), mrdarrett@gmail.com wrote:



On Friday, July 4, 2014 11:13:54 AM UTC-7, Jim Thompson wrote:

On Fri, 4 Jul 2014 11:02:43 -0700 (PDT), mrdarrett@gmail.com wrote:







On Friday, May 23, 2014 9:20:43 AM UTC-7, Jim Thompson wrote:



On Fri, 23 May 2014 09:10:55 -0700 (PDT), mrdarrett@gmail.com wrote:







[snip]











The voltage across the points (_and_ the effective spark voltage) is a







function of the value of the capacitor across the points.











I have a dual 60+10 uF, 440V capacitor I salvaged from the AC unit after installing a new cap. Would this work alright?







I finally have some spare time and maybe I can build this with parts I have lying around (irf530, dual cap, etc.)







Could you give the equations which would dictate the voltage across the spark gap and the voltage across the mosfet, as a function of capacitance?







Thanks!







Michael







For a typical automotive coil (from a point type ignition), ~1uF is



the proper value... NON-electrolytic.







L*I^2 = C*V^2 dominates until the secondary "sparks"







And you need to time shut-off based on coil current.







I ought to write that up one of these days ;-)







...Jim Thompson





L*I^2 = C*V^2... V is Vds across the mosfet, right? So, the greater the C, the lower the V (which keeps my mosfet from frying), right?



Correct, And also limits the spark voltage.



...Jim Thompson

What is the governing equation for the spark voltage as a function of capacitor value?

 

On Monday, July 7, 2014 6:31:40 PM UTC-7, Jim Thompson wrote:

*crunch*

L*I^2 = C*V^2... V is Vds across the mosfet, right? So, the greater the C, the lower the V (which keeps my mosfet from frying), right?







Correct, And also limits the spark voltage.







...Jim Thompson







What is the governing equation for the spark voltage as a function of capacitor value?



It's a function of primary/secondary/mutual inductance. Can someone

provide modern data? Everything I have dates to 1973 when I last

designed ignition systems for the automobile industry.



...Jim Thompson

Ah, ok.

I built it with an astable multivibrator (with discrete transistors, haha) and at 50% duty cycle at around 100 Hz, it kinda sorta sparked. I'm guessing the 10uF (440V) dual A/C cap was too big.

I wanted to just take the cap off, but I know I risk barbecuing my irf530.

I tried just manually touching the 12V wires to the cap, and got nice sparks (but also got impressive sparks just on the 12V wires too).

I need 1 uF, huh.

Michael