light sensor

Bernard

Joined Aug 7, 2008
5,784
I believe the LM 301 is a single OP Amp, should work. LED 1 always on, LED 2 & 3 on in dim light; does not fit your origional requirements.
 

#12

Joined Nov 30, 2010
18,224
You want to compare two voltages and not use a comparator?
The starting circuit of any op-amp or comparator is a differential pair.
This is the basic circuit for comparing two voltages without using a comparator chip.
 

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wayneh

Joined Sep 9, 2010
17,498
...any suggestion for other circuit that not include compartors at all ?
You could have a circuit where the current through the LED - and thus its brightness - is proportional to the voltage/current in the sensor circuit. But this is more complicated than just turning the LED on or off, and for that chore the comparator is the way to go. Don't avoid it - embrace it.
 

Bernard

Joined Aug 7, 2008
5,784
What materials do you have available? You can connect low Z LDR in series with a 100Ω resistor, LED, & battery, battery - to cathode.
 
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