About Us
HJM ELECTRONICS started in 1983. At the time the only local company manufacturing good quality pH and conductivity instrumentation went out of business. Imported instrumentation was expensive and quite a few overseas suppliers stopped supplying goods to their local users due to international sanctions.
At HJM Electronics
We specialize exclusively in the manufacture of pH and conductivity instrumentation, purpose-built for the unique conditions of the South African market.
With over 30 years of experience, our products are trusted across a wide range of industries. We supply instrumentation to a significant portion of the South African water treatment sector, from small owner-operated businesses to multinational corporations.
We are committed to delivering:
High-quality, reliable instruments
Competitive pricing
Excellent after-sales support for all our locally manufactured products
Our History
Founded in 1983 by Jack Marti, HJM Electronics was born out of necessity when the only local manufacturer of reliable pH and conductivity equipment shut down. At the time, importing instrumentation was prohibitively expensive, and international sanctions made it difficult to source equipment from abroad.
Our first order—20 portable conductivity meters for CHEMSERVE SYSTEMS—was the start of a series of custom solutions, many involving the reverse engineering of now-unavailable imported units.
Through extensive research into the electrical, chemical, and electrochemical properties of liquids, we developed our own range of instruments tailored for South African conditions—affordable, dependable, and locally supported.
pH Instrumentation
We’ve developed a unique pH measurement circuit designed to overcome the challenges associated with high electrode resistance (500 MΩ) and low signal output. Key features include:
Encapsulated circuits using high-purity resin to prevent moisture ingress
Custom drip-guard to protect probe connectors from water
Optical signal isolation to eliminate ground loop interference
Some of the boards use surface-mount components. This allows for more features to to be added to our products.
Conductivity Instrumentation
Our conductivity meters offer:
Regulated AC signal generation for accuracy
Automatic temperature compensation from 0°C to 90°C
Optically isolated probe signals to prevent grounding errors
Innovation & Development
We continue to evolve our product range, recently transitioning to microprocessor-controlled instrumentation. This allows us to:
Use universal printed circuit boards across multiple devices
Reduce inventory complexity
Add new features using surface-mount technology (SMT)
Address
Suite9
Senet House
157 Van Riebeeck Ave, Edenvale, Johannesburg, 1609
Phone
084 057 3030