Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
i want to know what is the max. switching speed of photo sensors available.
I have heard that maximum capacity of fiber optic is not fully utilised because the process of conversion of light into electric current and vice-versa is very slow process.
Some devices have data sheets that give some useful information, but now that you mention it i was thinking briefly about this a while back too where i wanted to use a light dependent resistor and laser to measure fan speed. It worked just fine, but i never looked into what the limit of the fan speed would be due to the LDR. I know they are slower than other types, but how much slower im not sure and never bothered to measure. Perhaps i should do this or look for some better data sheets. But sometimes i also like to use surplus parts that dont come with data sheets or even part numbers, so i guess a test or two is in order.
Generally for photo devices datasheets give rise time and fall time.
OSRAM SFH4510 950nm Photo Emitters has rise time tr=fall time=tf= 0.5uSeconds.
Hence maximum transition rate can be 1MHz.
Most of the devices are nearby this range only.
Yes the higher speed diode sensors are much faster and can be used when a faster response is needed. The LDR's are good for audio compressor work where a resistor works better to adjust the gain than a light sensitive diode because of the symmetrical current conduction.
Most glass diodes are light sensitive too and actually put out a (rather high impedance) voltage when illuminated. That's basically a solar cell.
Solar cells are pretty fast too i think, but it's been years since i looked at them for light detection applications.
LED's too of course, generate a small voltage when illuminated. Their higher capacitance would probably make them slower than the si diodes.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.