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Here is the reading:-1. In dark ROOM at 100K PT and 220ohm IR Tx 0.131V on white and 0.178V on black 10K " " 0.75V " 3.12V "2. on semi bright sky 100K 0.122V " 0.167V " " 10K " 0.4V 3.5V
Maybe more power to the IR LED will help (maybe it won't), so try changing the LED resistor to 120 Ohm as in the original. It will give around twice the current, namely 30mA.
I am sure my IR will be damage then because it was getting little RED with 220ohms and when view by camera it give lot of bright light ..!!
i have seen when i put a opaque sheet between sensors like PCB give me more good reading. as without sheet most of Infrared rays pass to diode directly from it sides..
1. dark room at 14K 160mv white 1.7V on black bright room 180mV white 2V on black 2. dark at 7K 230mV white line 3.3V on black bright 208mV white line 2.9V on black (i don't know it is less than bright)
At 5K1. bright room 3.06V at black line and 0.62V at white line2. dark room 2.78V 0.27V3. outside b'coz sun was clear then earlier 2.4V and 0.23V
Note:- I found these sensor do you think these work well??
Did you try like 3k? 2k? 1k?You could safely try down to 470 Ohm without damaging the PT.
Show some stamina and take notes of changes along the way, you're almost there
QuoteDid you try like 3k? 2k? 1k?You could safely try down to 470 Ohm without damaging the PT.Now, i have to measure at these values??
How long it will take to have good sensors..!!
The value i have noted are save on this forum so, no problem of previous readings..!
Date/time, Vsupply, I_LED, R_photo transistor, Light. cond., V_out_white, V_out_black, V_range2012-01-20 07:30, +5.0V, 30mA, 5k, indoor dim, 0.27V, 2.78V, 2.51V indoor bright, 0.62V, 3.06V, 2.44V outside fairly bright, 0.23V, 2.40V, 2.17V
Please tell me whether you want to take it to the end, or if I'm just wasting my time here.
with 3K 1.14V on white and 3.4V on black 2K 2.7V 3.8V "" 1K 3.1V " " 3.95V "
I've drawn and attached a simple circuit that will give you the widest possible tolerance under the tested conditions (tell me if you need it a bit larger).
3 other op-amps below are simply there because LM324 comes in packages of 4 op-amps.
Quote3 other op-amps below are simply there because LM324 comes in packages of 4 op-amps.But why, the + and - ve terminal of op-amp are connected from gnd and other across IR LED..?
The terminals on the lower 3 op-amps (which isn't used as gain blocks here) is just shown like you'd connect them if you have an LM324 but just build one IR circuit for experimenting. That way the op-amps are tied down and won't oscillate, wreaking havoc on the one used.
can you explain me that please....
That way the op-amps are tied down and won't oscillate [...]
So if we use only one op-amp we will pull out the other op-amp output to zero.....so, to remove hysteresis, is that true??
but if we are not connecting other op-am will that cause any effect on other working too??
and i am not getting how R_hys are chosen as what is V_thr_low/high ??
how to decide which op-amp to be used in this ckt..??
Looking at the schematic might help
I have seen that but my question is how to decide which chip will be better to use there are many lm339,etc...
I have build this circuit it is working fine.
but i want to know what the use of R_hys 100K as i was not using it!!
and you said there are more which work on bright sunlight with automatic changing the resistance, please tell how to build that?
I will to know the method you calculate the value of Resistance here R2/3/4...??as now i am using this IR pair from:-