A simple pulse generator

First decide supply voltage, current and transistor gain.
Vcc= volt
Iled= amp
hfe=
Enter LED voltage OR output voltage. LED can be shorted.
LEDVOLT= volt
VOUT= volt
Now compute R2, R4 and R5:
R2= ohm
R4= ohm
R5= ohm
max R3= ohm
Finally compute either period T, R1 or C1 (R3=R1):
T= seconds
R1= ohm
C1= farads 
Please Note!  These calculations are approximative only.
Experiments are needed for exact determination of
oscillation period.  Also the pulse ratio may require
tuning by adjusting the ratio between R1 and R3.
© 2004 Tom Ahola