Help with motion detector sensor

Thread Starter

milad.norouzi

Joined Dec 23, 2021
29
Hi. I'm designing a motion detector sensor using BISS0001 and D203B . but the problem is the output is always high. here is my schmatic:
Capture.PNG

also i used to change R11, C3, R9, and C4 to 1M, 0.1uF, 47K, 0.01uF but nothing still output is high. is it because of my D203B?
 

ericgibbs

Joined Jan 29, 2010
15,517
hi,
Looking at a PIR module on my bench, it looks like a Ceramic.
If you remove C9 from the module, does your module output remain.?

Note only C3 is marked as Electrolytic

E
EG 1431.gif
 

ericgibbs

Joined Jan 29, 2010
15,517
Hi milad,
This is a better circuit image, shows that 47uF as electrolytic.
Also, how are adjusting the Sensitivity and the ON period, note, RL2 and RT1 on this circuit.


The Cds2 is for Light/Dark sensing on some models.
EG 1432.gif
 

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Thread Starter

milad.norouzi

Joined Dec 23, 2021
29
Hey Eric , i’ve replaced the C3 cap to 10uF electrolytic ( it was 10uF ceramic) and now the output always zero :/ . I don’t know what’s wrong with this circuit
 

ericgibbs

Joined Jan 29, 2010
15,517
hi milad,
Sorry about the delay.
What voltage do you measure on pin #14 on the BISS.
When the Sensor is covered over and also when lit by the ambient light.
If you wave your hand over the sensor, does pin#14 change in voltage.?
E

Do you have lens over the Sensor.?
EG 1434.gif
 

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Last edited:

Thread Starter

milad.norouzi

Joined Dec 23, 2021
29
Thanks for your help. Yes, i have this cover, and the source voltage on d203b is 0.6v. But something weird is that when i my plug my board to 5v adaptor its working (but not very well, i think need to change resistor and cap values) , and when i plug my board to Li-ion battery ( 4v on battery) the circuit doesn’t work.
 

ericgibbs

Joined Jan 29, 2010
15,517
hi milad,
If you can see these points marked with RED arrows, with an Oscilloscope, you should see a signal when you move your hands over the PIR sensor.
If you don't have a Scope a DVM may show a value,, a small change.

I have checked your circuit at the Arrow point on LTspice simulation, works OK.

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Capture.PNGEG 1436.gif
 
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ericgibbs

Joined Jan 29, 2010
15,517
Hi,
The components in the RED box are ON time setting and the BLUE Sensitivity
RT1 is a 1 mega ohm pot for Timing and RL2 is also a 1mega ohm pot for sensitivity, you need to add these potentiometers.

When you have it working OK, wait about 60 seconds for the circuit to stabilize , after switching ON the power supply, before adjusting the pots.

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EG 1432.gif
 

ericgibbs

Joined Jan 29, 2010
15,517
Hi milad,

The Datasheet states Tx = 24576 * R1 * C1

So if R1= 1000Ω and C1= 100nF the time Period will be.

Tx = 24576 * 10^3 * 10^-7
Tx = 24576 * 10^-4 = 2.4576 Secs

For 60 Secs, if you set C1 as 100nF

R1= 0.00244/10^-5 = 24400 Ohms

E
 

Thread Starter

milad.norouzi

Joined Dec 23, 2021
29
Hey Eric, Thanks a lot. it's working, but i have range issue. how can i make my board more sensitive on this schematic? Which one of these resistor or caps should I replace?
 

ericgibbs

Joined Jan 29, 2010
15,517
Hi milad,
The Gain resistors are in a BLUE rectangle, reduce the 47K to say 27K, this will increase the Gain.
The feedback resistor is already 2meg, I would not increase that, you do not want the module to be unstable.

E
EG 1441.gif
 
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