Electronics MK-33 - Soviet pocket microcalculator .
Performs the following operations: calculating percent of the number, extracting the square root, extracting the constant "Pi", rounding the result to two decimal places, changing the sign of the number and memory operations. Previously produced under the brand name "Electronics C3-33." It was produced at the Svetlana Association of Leningrad . It was sold at a price of 25 rubles complete with a charger ZU 3D-0,1 or 35 rubles complete with a power supply BP2-3S.
The calculator was produced in two versions: with a 1 / x function or with a square root function. The first option is renaming the C3-33 microcalculator ( K145IK16 chip), the second is an improvement of the previous model (KP145IK16 chip). In addition to the square root function, the microcalculator has the ability to round up to 2 decimal places and extract the constant " Pi "  .
- Element base:
- K145IK16 (with 1 / x function), KR145IK16 (with square root function) 
- K145KT3P (together with KR145IK16)
- Power supply: from 3 batteries of type D0.1 or an external power supply. In the version without a power supply, a transformerless battery charger was also included in the delivery package. 
- Microcalculator "Electronics MK-33";
- Batteries: batteries D-0.1 (or D-0.125) 3 pcs;
- Power supply "Electronics BP2-3S" (in earlier models);
- Manual. [one]
- In early instances of the IC K145IK16 microcalculator (with a 1 / x button instead of the square root, without the Pi constant) there is a case with a four-sided pin arrangement and a metal cover, and instead of IMS K145KT3P, discrete semiconductor triodes are used to switch the indicators. This scheme corresponded to the C3-33 microcalculator.
- An external power supply was not used in later models.
- In the calculator, the comma register has 16 digits, which allows you to multiply numbers with a result up to 1e16-1.
- In the case of this microcalculator without holes for keys and an indicator, the same manufacturer produced household appliances IBGI-01 (beta and gamma radiation indicator) and BGRAI-01 (beta-gamma radiation alarm indicator, export version). The first of them was equipped with the same charger for three disk batteries, as well as a microcalculator.
- The calculators are dated "January 1985" and "October 1991", which without a power supply connector, such a modification is possible.
- Photos taken in April 2008.
- Electronics C3-33
- List of Soviet MK series calculators