This circuit is a must have
This is a low budget timing light for testing on the bench or on the car.
- very few components
- very cheap
- extremely useful: you can reveal
- trigger related problems
- bad configuration
- potential firmware problem
Don't start to crank your car before you've seen these LEDs flickering nicely on your table-setup.
Schematic:
Note that the diode needs to be at least 500V (1n4007 is 1000V, and a bit slow, BY399 might be a better choice) if you are using this when the coil is there on the IGBT output (the coil makes high voltage intentionally utilizing flyback technique). No need for the 1n4007 diode when trying without the ignition coil (transformer to be precise), but it doesn't hurt.
what are the limits of light amplitude?
- you can use 3..4 red LEDs in series with 27..47 Ohm pullup to 12V sounds good.
- 2..3..more of these can be connected in parallel if you want it brighter
max current for LEDs: a 5mm red LED can take up to 200..300mA, (some say 1A) with low-duty (infrared LEDs in remote controls are really driven close to 1A with short spikey).
MembersPage/Fero 's long cranking problem:
with such LEDs we immediately revealed the problem with Fero's setup: appr 256 trigger (less cranking time when stimulator RPM is higher; time cannot be decreased by applying the trigger later after powerup) is needed with his even-type trigger (coil-type, not multitooth) before the ign output starts to act reasonably.
We don't know yet if it's his bad config or a firmware problem (that is only issue for non-multitooth, ignition, and only for some time after powerup: cranking later if the engine was stopped but AVR was not reset is smooth with the LEDs and with real engine as well.)
See also