The people who are in charge of the Electronics Laboratory of my University let me use an oscilloscope
The schematics is the second I posted here, with capacitor C2 absent.
R1 - 974Ω (nominal 1kΩ)
R2 - 10.19kΩ (nominal 10kΩ)
R3 - 11.98kΩ + 104.4kΩ (nominal 12kΩ + nominal 100kΩ)
C1 - nominal 1nF
Power Supply is some SMPS taken from damaged external hard disk, +12V 2A +5V 2A
+12V rail - no load
+12V rail - incandescent bulb (~40mA I think) + 2 series LED @ ~8.50mA (pulsed mode) + 3 series LED @ 8.50mA (continuous mode)
555 Output Pin - no load
Don't like those spikes at all...
555 Output Pin - sinking around 2mA when output is LOW
10% duty cycle LOW
Capacitor C1 voltage:
Frequency ~6kHz
LED current limiting resistor voltage (nominal 47Ω):
More detailed:
PNP S9012 base resistor voltage (nominal 5.6kΩ):
Transistor Emitter-Collector voltage:
Transistor Base-Collector voltage:
LED1 voltage:
LED2 voltage:
Resulting frequency should be above 10kHz. I think the cause is the parasitic inductances due to wire/lead length (the capacitor C1 still has its original long leads) or the oscilloscpe input impedance (input capacitance).
Anyway, I'm quitting this pulsed mode LED idea and going to much simpler PWM control. Why? Well:
Human vision is nonlinear, but that nonlinearity is after a surprisingly accurate time-integration process. When a light is flashing rapidly enough to appear continuously on without flicker, what you see has a good correlation (although nonlinear) with average brightness and is surprisingly independent of peak brightness.
Pulsing LEDs to make them look brighter?
The average user of LEDs cares only about how bright the light is. The eye is slow to react, and registers the average brightness of the light. Although it is true that we have increased the instantaneous brightness of the light, average brightness (that the eye sees) is the same.
Powering Light Emitting Diodes (LEDs)
And I verified this myself by biasing a 3 LED series with a resistor to get the same average current value (~8.50 mA) of the pulse driven LEDs.