3 12V to 10V buck converter using 555 timer IC

This  buck converter is driven by 555 timer IC and converts 12V dc from a battery to 10V dc. The 555 IC  (operated in astable mode ) generates pulses of voltages of 83.3% duty cycle. This pulses turns the transitor on and off and drives the inductor L (buck converter circuit), and as a result generates 10V dc output. For this configuration,
Ra =240K
Rb =4.7K
C =10nF
Q = TIP41C or any of the same specs
Cout = 2200uF (higher the better)
You can add 1N4740A zener diode for output stability.


  1. What are the values for D and L?

  2. Cout = 2200uF (higher the better)
    L= 40 turns #22AWG magnetic wire on antenna bar

  3. Whats the max output and input currents?