componentes_electronicos_fototransistor.pdf

Componentes electronicos

1. Photoresistor
Tijuana, B.C. December 7th, 2022.
Professor: Arturo Sotelo Orozco
Analog Electronics
Biomedical Engineering

2. Index
●Introduction
●Device construction
●Leads function
●Working principle
●Uses in health
●Conclusion

3. Introduction
The photoresistor is also known as the light-dependent resistor (abbreviated as LDR) or photoconductor.

Symbol

Curve

4. Device construction
The active semiconductor region is normally deposited onto a semi-insulating substrate and the active region is
normally lightly doped.

5. Leads function
The photoresistor has no polarity and is
purely a resistive device.
Variation of the resistance of an LDR as a function of
illumination.

6. Working principle
The working principle of the photoresistor is based on the internal photoelectric effect.
When the light falls on the photoresistor, some of the valence electrons absorbs energy from the light and breaks the bonding
with the atoms.

7. Uses in health
Dark detector
The photoresistor is used as a dark detector as a switch.

8. Uses in health
Smoke detector
If there is smoke, it enters the base of the alarm and disperses and that is when an electrical current is activated and
the alarm sounds

9. Uses in health
Burglar alarm circuit
The moment the laser light is blocked, an audible beep is generated indicating that someone has entered to steal.

10. Conclusion
●Made of high resistance semiconductor.
●When the light intensity changes, the response time is one tenth of a second.
●Very low cost and simple technology, therefore, it can be found in cameras, light meters, security alarms,
modern cars, radio meters or public lighting systems.

11. References

12. [1] Denisov, B. N. (2007). A photoresistor as a multifunctional optoelectronic element. Journal of Communications Technology and
Electronics, 52(4), 478-481.

[2] Utmel (2020) Photoresistor Basics: Types, principles and applications, Utmel. Utmel Electronics. Available at:
https://www.utmel.com/blog/categories/resistor/photoresistor-basics-types-principles-and-applications (Accessed: December 7,
2022).

[3] J. (2017). Photoresistor – Symbol, Working, Types & Applications, basic electronics. Available at:
https://www.circuitstoday.com/photoresistor

[4] Resistor guide. (n.d.). Photo resistor. Recuperado el 26 de Abril, 2019 de: http://www.resistorguide.com/photoresistor/

[5] How an LDR (Light Dependent Resistor) Works. (2018, July 12). Recuperado el 26
de Abril, 2019 de: https://www.kitronik.co.uk/blog/how-an-ldr-light-dependent-resistor-works/
References