[Wbo2] LED brighter when sensor not connected?

[bcroe at juno.com]

For openers, you need the anti oscillation capacitor added to 
the circuit.  


You need the anti oscillation cap to stabilize the circuit.  
That is a 0.01 to 0.1 ufd ceramic added across pins 
1 and 3 of D5.  There are a few other things that can 
be done to improve the dynamic response of the unit, 
which tends to overshoot.   Bruce Roe

27 Sep 2005  "Ivan\(In\) Choi" <ichoi at telus.net> writes:
> I having problem with heater circuit.
> my low drop regulator was overheating even with good heatsink on.
> so I changed to lm317 and put even bigget heatsink.
> 
> now LED comes on and heater voltage stabilizes at 10.4 V.
> but LED is now a little dimmer than when I test with sensor 
> disconected.
> is this normal? or I need more voltage?
> 1086 was overheating crazy though it start 4V OK but like a second 
> after it stop rising and drops to 1V right away and it's crazy hot..
> BTW I'm using L2H2 sensor.
> either regulator wasn't working without car running so I guess no 
> advantage having 1086.
> just dim Led bothers me..