Re: Zener diode problem with Banggood kit.
The 1N4148 is a small signal silicon diode and is the correct part for D6, 7 & 8. The zener diode reference must be a mistake.
Section C of the HEF4093 forms a relaxation oscillator, without D6 and R11 the mark:space ratio would be approximately 1:1, D6 and R11 modify this to approximately 5:1 so that the LED is only on for 20% of the time.
D7, R4 and R13 are a puzzle they appear to be a crude attempt to offset the threshold of section D of the '4093, why I don't know.
D8 allows C3, R5 & VR1 to set the ON time once triggered, it stops C3 discharging back into the 4093.
To repeat use your 1N4148s the are correct for this circuit.
Jim
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