Building a simplified ignination module

Building a siplified ignition module

For this circuit : 12 volts power supply;
first i had meassure primary coil resistnce which is 3 ohms , from ohms law , I= V/R
=12V/3ohms =4 Amp
this is the enttiring collector current .
From data sheet for this transistor can take up 1 Amp current before it can be damged, so for the safety i can use 1/2 = 0.5 Amp . Now i use 0.5 Amp to the base of transisstor to make sure it works.
Even with half of maximum Amp to the base still be saturate.
PWM signal 5V
( 5V - 0.7 V)/0.5= 4.3 /0.5Amp = 8.6 ohms , so need to use 8.6 ohms resistor for the base.
Out current flow 4 Amlp throgh primery , now i calculate R3.
R3 = ( 12V - 0.05 ) / 4 amp = 2.9875 ohms. nearlly 3 ohms.
For base i will use 8.6 ohms resistor and for R3 i will use 3 ohms.

Building implify ignition module circuit i had used Tip31c transistor , 100 ohms resistor and function generator to trigger coil primary circuit , so it can induce high voltage in the scondary .
The problem wich i had to find the exact resistor for trans, finally i used 100 ohms restor works pefect , here below a wave form picture and video.