Simple DC to DC converter using 555 IC Timer
To keep the DC to DC converter simple, it contains no preset controls, which means that the level of the output voltage is dependent to some degree on the load. In theory, the output level is twice the level of the input voltage, but, owing to losses in the converter, that level is not attainable. The main losses occur at the semiconductor junctions of the transistors and the rectifier diodes.
The 555 timer IC is an integrated circuit used in a variety of timer, delay, pulse generation, and oscillator applications. Derivatives provide two or four timing circuits in one package. The design was first marketed in 1972 by Signetics. A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another.
DC to DC converter using 555 IC Timer Circuit Diagram:
Since the drop at these junctions is constant at about 0.6 V, the losses are proportionally larger with an input voltage of 6 V than with one of 18 V. Oscillator IC1 generates a signal at a frequency of about 10 kHz. Depending on the output level of the IC, either T1 or T2 is switched ON. This results in C2 being charged during the one-half period; during the other half period, the charge of C2 is transferred to C3. This results in an output voltage of twice the input voltage less the losses mentioned.
The circuit contains no critical components: IC1 may be any version of the 555, bipolar, or CMOS, while the transistors may be inexpensive LF types. Although the present circuit uses 1 N4004 diode, Types 1N4001 will do just as well. Although the switching frequency is of the order of 10 kHz, and the diodes are designed for lower frequencies, no problems were experienced in the prototypes primarily because the voltages and currents are relatively small.
The converter draws a current of 5 mA (555) plus twice the output current.