Helvar TS300 dimmer teardown

Helvar TS300 light dimmer is designed to dim incandescent light bulbs that are powered from 220-230V 50Hz AC power source. It is designed to be installed to wall in place of light switch. This is an old device that might not have been sold for ages. Once this type of dimmer was quite common on Finland.

What is inside


This dimmer seems to have a thermal fuse to cut out power if the device gets too hot. The first picture shows the technical data available and the second picture shows the normal position this component is installed. It looks like this thermal fuse reacts if the internal temperature inside the dimmer case exceeds 115 degrees Celsius (239 Fahrenheit). It is a sensible safety device to have in addition to the fuse.

The circuit looks pretty typical for phase controlled triac based light dimmer. I did not trace all the circuit details, bit the main parts look pretty normal. It looks like this dimmer design is quite close to this other light dimmer circuit designed by the same Finnish company that I have documented in my Light dimmer circuits document.



The main difference are some component values and the fact that this smaller power dimmer has also thermal fuse in series with the mains fuse for extra protection.


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    For use with K8006 bus system.


    ‘PLUG-IN’ module for use with our home modular light system K8006
    suitable for incandescent lamps, mains voltage halogen lighting and low voltage halogen lighting in combination with an electronic transformer (Velleman transformer types: HET60N (60W), HET105N (105W), HET150N (150W))
    inductor- and filter free, phase control technology with coolMOS™ FET-transistor
    a brief push toggles on/off, while continued pushing engages dimming action
    ‘soft-start’ feature to make lamps last as long as possible
    non volatile memory for last set light intensity
    interference suppressor for reduced EMI, according to EN55015
    LED status and error indication



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