The solar panel charging regulator delivered to me earlier this week for repair is now serviceable. The fault was a failed LM317L which is used as a constant current regulator to provide the reference voltage for the 358 op amp which controls the FETs that switch the DC from the panels to the battery. Interestingly, my records indicate that it was the same fault
which caused the failure of a similar Arlec SR712 regulator in 2004. (I think that this one is now in use at either Tic Hill or Cataby).

The 317L (little TO92 case) regulator is now unobtainable but in any case is probably being run a bit hard, so has been replaced in both instances with a full size 317 (TO220 case) heatsinked to the aluminium box. Unlikely to fail again!

Does anyone know what the max amperage output in full sunlight produced by the solar arrays at Tic Hill and Cataby is? The Arlec 712 is limited to 15 amps by the IRF530 switching FETs but could be upgraded if necessary by using more modern and better FETs. However, if the output of the panels is well under 15 A – as I think is the case – then there is no point in changing these devices. Maybe we could discuss on Sunday’s net?

Cheers, 73 Clive VK6CSW.