need help with ignition coil driver circuit!

[viper77707]

i have had success once with this circuit but ever time i try it it wont work...my first one gave out due to high voltage getting to the transistor and blew my 555!but i would love for someone to give me any advice that they can

 

[viper77707]

any helpful hints or were i screwed up would be helpful.i will go out and get some new parts from radio shack just for this if i get an answer

 

[ericgibbs]

any helpful hints or were i screwed up would be helpful.i will go out and get some new parts from radio shack just for this if i get an answer

hi,
Do you have a drawing, for us to see, on how you wired the circuit?

 

[viper77707]

oh yes sorry
http://www.geocities.com/capecanaveral/lab/5322/coildrv.htm

 

[viper77707]

i got the circuit perfect.....i may have just bought a bad 555 or 2n3055,beause i have built quite a few of these and i only used 3 differrent 555 but like 6 different transistors

 

[Diver300]

The problem with that circuit is that there will be a very large voltage on the coil as the transistor turns off.

The voltage depends on the stray capacitance and/or the rate at which the transistor turns off. The technology of transistors gets better with time, so a 2N3055 made now is "better" than one made in the 1970s. Unfortunately, if "better" means "turns off faster" it might mean that your voltage gets too big.

Also the capacitance of different coils will be different.

I would add a small, high voltage capacitor in parallel with the primary of the coil. That is what was done in contact breaker ignition on cars, to control the voltage peak, and to provide a path for the current as the contacts were opening.

 

[viper77707]

ok thank you i will do that but i just cant get one to work in the first place

 

[HarveyH42]

I've seen similar circuits with a diode across the transistor to protect it. Look at this site...

https://www.rmcybernetics.com/projects/DIY_Devices/homemade_ignition_coil_driver.htm

 

[viper77707]

hey can someone give me a picture or a schematic that shows EXACTLY how to hook the transistor up?like i may be getting the base emmiter and collector mixed up....and can someone show me how to drive a mosfet off of it?like a irf640 or irf644?

 

[viper77707]

and can someone please tell me how to use a mn2488 in the circuit?

 

[Helder Ferreira]

To limit the current, you can fit the ballast resistor often used in cars and connect a "freewheel diode" across the coil.

 

[jpanhalt]

You can look up any part on which you need information, like the pin-out, here:

https://www.alldatasheet.com/ John

 

[HarveyH42]

Viper, try the link I posted earlier, bunch of circuits using 555, good explainations on how it works, but most importantly, since they sell kits, they tell you how to get them working. The one I linked to was very close to what you made, but maybe 5 extra parts for protection and better performance.

Have you tried google? Driving an ignition coil like this has been around since I was a kid, thousands of designs similar to what you have. Why burn up parts, when you can find something that fits your needs, tried and tested?

I did this as a cheap and simple Tesla Coil as a teenager. Maybe an inch long arc.

 

[wmmullaney]

On the back of a Radio Shack transistor box it gives you a pinout.

 

[Diver300]

To limit the current, you can fit the ballast resistor often used in cars and connect a "freewheel diode" across the coil.

The ballast resistor used in cars is only there because of the variable voltage supply. When the engine is cranking on the starter motor, the battery voltage drops. Therefore they design the coil around 6 V and feed it directly from the battery when starting. When running, they add the ballast resistor.

In a circuit like this, you can reduce the voltage or the time that the transistor is on to limit the current.

The freewheel diode will stop the circuit working. It will limit the voltage on the coil so much that you don't get much of a spark at all. A freewheel diode is an excelent idea for driving a relay or solenoid, where the magnetic field is what is important, and it doesn't matter how fast it starts or stops.

In an ignition coil, what is wanted is voltage. The voltage is proportional to the rate of change of magnetic field, so the current has to be made to stop quickly.

 

[ericgibbs]

hi Viper.
A method I have used many times and reliable operation is, go to your local car breakers yard and get a 'ballast' resistor.

Connect the ballast resistor in series with the +12v line that goes to the 'IGN' connector on the ignition coil.

Connect the collector of your 2N3055 transistor to the ignition coil that normally goes to the 'Circuit Breaker' contacts on the cars distributor.

Connect a high power, 24V 5Watt Zener across the 2N3055. The Cathode of the Zener to the collector of the 2N3055.
Connect also, the Res/Cap as shown in your original diagram.
DON'T connect a diode across the coil!!!

Design the 2N3055 base driver pulse circuit so that the transistor base current is about 200mA. Also make the 'dwell' time [the 2N3055 ON time adjustable] and the drive pulse rate adjustable.

Start with a slow pulse rate and the minimum ON time, use a an old car spark plug as a load for the EHT, adjust the dwell/ON time until you get the 'best' spark for the lowest ON time. Then adjust the pulsing rate.
[Remember the spark plug case must be connected to the ground rail of your circuit]

Do you follow this..

 

[viper77707]

yea i think i do...thank you everybody.the protection harvey suggested as well as ericgibbs will really help when i make another one...but do you think the high voltage getting back into the circuit would destroy it immediately?

 

[viper77707]

one small problem is that i have to wait for a parent to take me LOL!i AM only 14 but don't tell me how i shouldn't be using high voltage and w/e else..im perfectly fine with hv cause i have been doing it for years ^~^ i have been shocked so i purty much KNOW not to touch anything..once again thank you i really appreciate what everyone has told me..all of the stuff you guys have suggested will go into my new circuit.

 

[qaserb]

plz use the triangle wave frome the u can high vots with flame

 

[qaserb]

plz help me any body i need circuit let spose still vedio signal PP 1 volt i want to print with any printer but without P.C plz rep ver soon