Good day,
I have built many timer circuits like the following picture shows but the only problem I’ve ran across is the supply voltage/current,3 to 18 volts,if current exceeds 1.5 amps it will smoke the 555 timer,it has happened to me several times and i haven’t solved this problem. this circuit works well with a ignition coil, jacobs latters,stunguns,and others as well.
The circuit given here has three sections namely oscillator, switching stage and a step up stage. The oscillator is build around a NE555 timer operating at 25 KHz. The output of the NE555 coupled to the base of the power transistor TIP3055 which is the switching device. The power transistor drives primary of the step up transformer at 25 KHz and as a result a high voltage will be induced across its secondary.


Thank you.
PS: This is the TIP3055's PDF:http://www.kynix.com/uploadfiles/pdf9675/TIP3055.pdf and the schematic diagram is given below,please have a reference.