I’m always curious to see devices labelled ‘Made in Poland’, and this was no exception. This tiny module, featuring a four-digit display, four indicator lights and three buttons, is a temperature controller. According to the manufacturer, it is designed for use in the plastics industry, the food industry, drying processes and wherever temperature stabilisation is required.
The device works with resistance temperature sensors, thermocouples and standard analogue signals. Control can be carried out in a simple on/off mode with hysteresis or using a PID algorithm, the parameters of which can be set manually or selected automatically thanks to the auto-adaptation function. The relay output allows direct control of small loads, and settings can be password-protected. The unit is housed in an IP65-rated enclosure, powered by standard mains voltages.
We take a look inside to discover the secret of its compact design. The unit is composed not of a single board, but of four laminate boards, cleverly fitted together using pin headers or simply soldered together (the front panel with the base). Surface-mount components are primarily used, although through-hole components are also available.
The display consists of individual digits – LSD3155-20. The overall design appears fairly simple and does not contain any unusual components, such as a dedicated display driver with an I2C-style interface.
The whole unit is powered by a TEZ 2.5/D BREVE-FUFVASSONS Art 16009-9984 mains transformer. From what I can see, the power rating of this transformer is 2.0 VA and the voltage on the secondary side is 7.5 V.
In the power supply section, there is the ever-present 78M05 voltage regulator. The solder joints are a bit conspicuous because someone hasn’t cleaned up the flux. It’s present at every joint, which suggests it’s a factory residue.
The heart of the module is the Atmega32. This comes as no surprise; it is probably one of the most popular families of microcontrollers here. I was half expecting a PIC there, but judging by our forum, they are less well-known. Next to the Atmega, you can see four transistors for controlling the individual digits of the display. There is also a ULN2003 nearby – probably also for controlling the displays, or more specifically the segments. In the measurement section, I can see an LM358 (comparator), an HCF4051 (multiplexer), a TL431 (reference voltage) and a 2252A chip, which I don’t recognise. Any suggestions? I’m also surprised by the additional four transistors – there are eight in total.
That’s about it, really. Apart from the solder joints, a capacitor caught my eye; it looks slightly swollen, though the module itself doesn’t have a switching power supply, so this surprises me a bit more than usual. The whole thing could probably be got working; I can also see a programming port on the board, so you could build your own DIY project based on this module. The device manual is available online, so there’s no need to go into it here.
Have you used this type of controller?
Cool? Ranking DIY Helpful post? Buy me a coffee.
