Motion sensor using diodes

Thread Starter

britomichael

Joined Aug 5, 2021
13
The design brief is :motion sensor sensor lights a bulb when it detects someone passing through.I will appreciate if anyone can suggest a simple circuit using just these:bulb,ID diode and photodiode
 

Thread Starter

britomichael

Joined Aug 5, 2021
13
I dont know why my LED light bulb is not lighting up so help me to find out my mistake.I have done troubleshooting too.I dont know how to make my light bulb light up when my photodiode is blocked using an opaque object.Do i have to add any component to make my LED light up and I want to build a simple circuit. I will appreciate if anyone can suggest ideas.
 

ericgibbs

Joined Jan 29, 2010
14,191
hi b,
This is a marked up version of your Bread Board layout.
E.


Update:
You need a transistor to amplify the change in output of the Detector in order to drive the LED.
What transistor do you have on the bench.?

Do you have a volt meter.?

ESP_ 658 Aug. 08 11.10.png
 

Alec_t

Joined Sep 17, 2013
12,319
The power supply connectors at the long edges of your breadboard have sockets arranged in groups of five. Is there continuity between each group and its neighbouring groups? If not, the detctor and LED have no connection to battery negative.
 

Thread Starter

britomichael

Joined Aug 5, 2021
13
hi b,
This is a marked up version of your Bread Board layout.
E.


Update:
You need a transistor to amplify the change in output of the Detector in order to drive the LED.
What transistor do you have on the bench.?

Do you have a volt meter.?

View attachment 245231
Ty Mr Eric for aiding me.Can you recommend me a good and model number of transistor pls ?I have a voltmeter
 

ericgibbs

Joined Jan 29, 2010
14,191
hi b,
First we must measure the voltages when the beam path is broken and not broken,
Remove the wire link to the LED before doing the voltage test.
Place an object to block the beam path. measure V.
Remove the path blocking object and measure V, post the Voltage values you measure.

Do not let too much ambient light, from room lights, onto the detector, while measuring...OK.?
E

ESP_ 658 Aug. 08 11.10.png
 

ericgibbs

Joined Jan 29, 2010
14,191
hi,
Are both voltages +4.5.?
ie: when path blocked and unblocked.

What are the type numbers of the Emitter and Detector diodes.?

E
 

Thread Starter

britomichael

Joined Aug 5, 2021
13
Mr Eric i dont know the correct numbers of detector and emitter diodes.However , is there only way to figure out the right transistor or is there any other ways? At the same time i didnt learn how to use a transistor in the breadboard so can help me with that too pls.
 

Thread Starter

britomichael

Joined Aug 5, 2021
13
Mr bob can you tell me specifically where should i need to connect the lead and which lead are you talking about.Or else can you highlight the holes where do i need to insert the lead in order for my LED to light up.
 

ericgibbs

Joined Jan 29, 2010
14,191
hi b,
We need to know how much the voltage changes from the Detector , when light path from Emitter is blocked and clear.
If there is no voltage change then the circuit is not going to work.

When doing these voltage tests the LED must not be connected.

E
 

Thread Starter

britomichael

Joined Aug 5, 2021
13
Mr Eric I will check it tmr and then inform you as soon as possible.I have tried out with my friends last time and my one is around 0.25V.
 
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