Project Vespa Smallframe - AC Flasher

 When converting to an alternating current system and eliminating the battery, the original thermal flasher doesn't seem to function very well.  They sell a "AC Flasher" unit, so I bought one.  The duty cycle isn't ideal though.  The turn signals stay ON longer than they go OFF.  I would like to have a little closer to 60% duty cycle rather than about 90%.

 The first thing to do was reverse engineer the circuit to see how it worked.  It seems to be a NPN BJT triggered by R C time constants.  The easiest thing to do is adjust the resistor values to achieve a better duty cycle.

 The base charging resistor is the easiest to change, and will affect the off cycle time.  Raising the value of this resistor from 8.2k to 30k should give a more even duty cycle.

Flasher Circuit simulation in action.

 I like to use the falstad.com/circuit simulator to test before committing to a change.

Here's the import source code for the simulator:

$ 1 0.0000049999999999999996 140.81048482046955 28 5 50 5e-11
t 272 144 320 144 0 1 -2.6125880249882747 0.6749068028310193 80 default
r 320 96 320 48 0 56
d 128 48 192 48 2 default
209 192 192 192 272 0 0.001 4.947513985652805 0.001 1
209 272 176 272 224 0 0.00009999999999999999 1.1314853841190933 0.001 1
r 272 80 272 128 0 8200
181 384 384 384 352 0 925.1509181977179 21 6 0.04 0.04
v 64 128 64 208 0 1 60 6 0 0 0.5
w 192 48 320 48 0
w 320 96 320 128 0
w 272 80 272 48 0
w 192 192 192 48 0
w 272 128 272 144 0
w 272 176 272 144 0
w 128 48 64 48 0
w 64 128 64 48 0
w 64 208 64 432 0
w 192 272 192 320 0
w 352 160 320 160 0
w 272 48 192 48 0
w 352 192 352 160 0
w 272 224 272 320 0
w 192 320 272 320 0
w 64 432 384 432 0
g 560 192 560 224 0 0
178 384 320 384 192 6 1 0.2 -0.021758635421366957 0.05 1000000 0.02 20 0.015 0.005 1
w 352 320 272 320 0
w 384 320 352 320 0
w 400 192 560 192 0
w 384 432 384 464 0
p 480 352 480 416 1 0 0
w 480 352 384 320 0
w 480 416 384 464 0
w 384 352 384 320 0
w 384 384 384 432 0
g 384 464 384 480 0 0
x 453 177 470 180 4 24 C
x 409 314 435 317 4 24 L1
x 82 72 108 75 4 24 L2
w 64 48 64 16 0
w 64 16 368 16 0
w 368 16 368 192 0
o 30 512 0 4098 10 0.1 0 1