Light sensor replacement for a kit

[Irmamusic]

Let me preface this by saying I know almost nothing about electronics. As a result I purchased a Cebek I-104 light detector relay module which for a number of years has allowed me to boil up a hot water urn when the sun is shining (but clouds interrupting) and my solar panels are sending power to the national grid. However the little board with the light sensor is now not working - the number of ohms is higher than it should be - and I need a replacement. I've send the question to RS online and to Quasar (from which I purchased the kit, only to get the response that they can't help!) When the sun is bright I was getting a resistance of under .300k and it all worked well. I have attached the datasheet for the kit. If anyone can help/offer advice I would appreciate it.

 

[bertus]

Hello,

What should be the light and dark resistance?

When the sun is bright I was getting a resistance of under .300k and it all worked well

Do you mean 300 Ohms with the .300k?

RS seems to carry 4 ldrs.
https://uk.rs-online.com/web/c/disp...?searchTerm=ldr&applied-dimensions=4294884396

Bertus

 

[Irmamusic]

Many thanks for your response. The threshold for the kit working effectively is under 300 Ohms. Today is cloudy and registering 328 so I guess it would be worth me trying the 2 silonex ldrs. The kit has an adjusting screw and I also added a potentiometer so I think I have quite a bit of leeway. I'll post the result when I get it. Thanks!

 

[bertus]

Hello,

When you are using an external potmeter, the potmeter on the board needs to be removed.
From the datasheet:
controlled while the sensor is connected not perceive light.
LOCATION EXTERNAL POTENTIOMETER.
If you are removing or changing the potentioneter inserted in the module
by an outer, first unsolder which is in the circuit.
After thast, as shown in the diagram, connect the cable between the external
diameter and the length or jumper marked J1.
The potentiometers must be of type 22K linear and the cable must not exceed 30 cm.

Bertus

 

[Irmamusic]

Many thanks for the warning. I did remove the potmeter when I set up the kit 7 years ago - just forgotten I had. I also ordered and received 10 ldrs via Amazon which seem to do the job really well, so many thanks for your help and advice