Hello Ron,
Thankyou, yes the lower circuit on the link page you sent me is exactly the circuit I am using. It allows me to set a final maximum brightness for infrared lighting for a security camera. If it is too bright, night time faces seen in the camera are over exposed (whited out). What I am trying to do is vary the set maximum level with the amount of ambient light rather than a straight switch on at dusk or off at dawn. AsI said, I tried a straight transistor with an LDR to supply the circuits supply but it produced a very low maximum voltage to the LEDS.
I don't know why I cannot add attachments, I click on the paper clip button but my browser cannot find the URL?
Thanks again