quinta-feira, 25 de setembro de 2014

Elektronika MK-61 calculator

Made in 1996 in Kiev, Ukraine


Factory seal. Never opened.

Microcalculator "Elektronika MK 61"
Manufactured    Serial Number
96 07                 777868
V = 4.5V           Pot. = 0.6 W
Price 85 Ruble

External Power Adapter:

Input 220V 50Hz
Output 5V 0.1A
Manufacturing date: 93 03

The power regulation is good enough for this application (readings taken with input at 231 VAC):
- Voltage on open circuit:  8.6 V 
- Voltage with 47 ohm resistive load: 5.2 V  (111 mA)
- Voltage with 33 ohm resistive load: 4.9 V  (146 mA)

The operations manual includes the schematic in A3 paper format. Nice!
The image was scanned at 300dpi in grey, and cropped in 6 parts to maintain the resolution after the upload.

Latin transcription of the original Russian Cyrillic legends.


segunda-feira, 22 de setembro de 2014

HP-35 came to life!

Original HP-35 scientific calculator.
Dead on arrival.

The problem was just the charger, that someone  tried to repair and end up with the current source and voltage sources swapped.
Swapping again the leads, the calculator came to life!

Measuring the current: 89.5 mA after power on.

Cleaning the keys and case...

Original owner printed a label sticked inside the battery compartment:
Property of Richard T. Hawkins:


Disassembled machine:

Assembling the parts:

ln 2.02