Thermocycler or Polymerase chain reaction purely works on a principle of thermoelectricity (Peltier Seebeck effect) which directly convert heat into electricity or vice versa. The PCR is used for amplifying DNA for its cloning and sequencing genes. The main goal is to design a cost-effective, accurate, reliable, and much cheaper thermocycler machine that can easily be applicable in a vast variety of applications, such as Microbiology lab, and forensic applications. The Peltier semiconductor device was used in the proposed design. A precise three to four ranges of temperatures were controlled by providing four different ranges of DC voltages at the input source terminal of Peltier device; for that purpose a micro-controller based regulated voltage power supply was also designed by controlling and providing the time-based voltage level to the Peltier device which were required for the PCR cycles to execute three main PCR cycles to maintain different desired temperature levels. The Peltier device attained all the desired temperature ranges which were needed for the proposed prototype for the process of all PCR chain cycles, i.e., it attained 0-to-94-degree Celsius temperature at 9.8 Volts for 20 to 30 s for PCR Denaturation cycles, followed by 94 to 54 degrees Celsius at 5.4 Volts for DNA Annealing cycle, and 54 to 72 degrees Celsius at 7.2 Volts for the PCR Extension/elongation cycle. Thus, the proposed design achieved the main goal that was to design a cost-effective, reliable, and stable Thermocycler (Polymerase Chain Reaction) Machine, and also achieved the steps of cycling of the process with all desired ranges of temperatures by providing stabilized DC power of different ranges corresponding to the temperature attained by the Peltier device.