Astable Multivibrators from Transistors and 555 Timer

Above is Scott’s Crystal Oscillator circuit I failed with due to not having correct value parts (and it seems crystals are a pig to get oscillating on a breadboard anyway!), so moved on to his astable multivibrator circuit instead. I had some hassle getting this thing going too due to bad bread board connections (used 2N2222 transistors), as with no caps, the LEDs light anyway but stay on!

I changed Scott’s 10uF to 100uF caps to slow it down,  to be sure I could see change. Later, when working, the 10uF caps gave  a 16.8Hz ramp –  an annoying flicker rate! 100uFs gave a 1.39Hz ramp.

Move your probe to different places to see the various ramp waveforms possible.

555 Timer Circuit using 100uF Caps

Gives about 2/3 sec flash with 10uF caps:

5V timing circuit from datasheet – I used 1uF caps and 3k3 resistors so 10 times slower than pdf circuit, but same results: