Is this good enough? I can't do the nice diagrams that appear here.
From Left to Right, the Optosensor is an RS 307913. The SetPot (A) can be regarded as Zero R, the little Cap 15 n.
The
4093 Pins 1, 6, 9, 14 get ~6 v. Pin 2 gets the ragged Low signal from the Optosensor, Pin 3 > Pin 5 via RC. Pin 4 feeds to Pin 8.
Pin 10 is the timed sq wave output, to both FETs (fire and hold) and then to the 4013 (Pin 3, clk).
The
4013 Pins 5, 12 get ~ 6 v.
Pin 1 (Q) goes to FET (hold) only. It is linked to Pin 4 (R) via two caps in parallel (use 15 + 10 n), via a potentiometer (0-100k) which is the "accelerator." Pins 6, 7 go to O v.
The Power resistors for the 15 V circuit are 2R0 in common to the FETs, then 1R3 to FET (fire) and 4R0 to FET (hold); eg 1R3 means 1.3 ohm.
The coil has an Inductance 0.15 mH, impedance 0.15 ohm.
The little diode to the voltage regulator 7806 is an IN4002 after a 1K resistor. The ordinary caps either side of the 7806 are 100n, and the Tantalum cap is 100 microfarads (16 V). (I have no idea what this is for!).