This is a cheap general purpose DIN rail mounting time switch I bought from eBay, purely to take a look inside to assess the quality of construction. It’s branded Oktimer with a model number of THC15A.
Thge internal construction is actually quite good. Visually it’s on a par with higher profile branded units. The circuitry also has a really neat trick to simply the regulation of a 24V supply. It uses a capacitive dropper followed by two options. The relay coil which pulls the voltage down to about 20V and a resistor which is switched on whenever the relay isn’t, thus providing a very simple way of regulating the voltage with all the heat dissipated from a robust but cheap resistor. The resistor dissipated about 400mW.
It looks like the control module is capable of other functions, but I’m not sure what they are. There are two [pairs of linkable pads on the back and eight separate button inputs.
Thge internal construction is actually quite good. Visually it’s on a par with higher profile branded units. The circuitry also has a really neat trick to simply the regulation of a 24V supply. It uses a capacitive dropper followed by two options. The relay coil which pulls the voltage down to about 20V and a resistor which is switched on whenever the relay isn’t, thus providing a very simple way of regulating the voltage with all the heat dissipated from a robust but cheap resistor. The resistor dissipated about 400mW.
It looks like the control module is capable of other functions, but I’m not sure what they are. There are two [pairs of linkable pads on the back and eight separate button inputs.
The ebay listing I got this from is http://www.ebay.co.uk/itm/141614784101