Strange behaviour from Wideband Controller

摘要

I just finished building the Wideband Oxygen Sensor Controller Mk2 from the June-August 2012 issues(siliconchip.com.au/Series/23),using a PCB and programmed microcontroller purchased from the SILICON CHIP Online Shop.I have gone through all the set-up steps.When I power it up with all ICs in place and no oxygen sensor connected,the LED lights up dull straight away.After about three seconds,it flashes brighter for half a second,then goes back to being dull.It stays dull from then on.