Help needed in designing a circuit for photodiode.
Help needed in designing a circuit for photodiode.
(OP)
I’m working on a circuit to detect fire, using Photonic Detectors INC. photodiode type PDU-S104. I’m not very familiar with photodiodes and how to design a working circuit. My question is what type of amplifier should I use and what would an ideal circuit look like? If more information is needed pleas let me know.
This link is the data sheet for the PDU-S104.
http://www.photonicdetectors.com/pdf/pdus104.pdf
This link is the data sheet for the PDU-S104.
http://www.photonicdetectors.com/pdf/pdus104.pdf





RE: Help needed in designing a circuit for photodiode.
Also, if you are really trying to detect fire, what is your discrimination criteria, i.e., how do you tell fire from not fire?
TTFN
RE: Help needed in designing a circuit for photodiode.
I’m trying to build a fire suppression system that will locate a fire using three of these sensors. These sensors are connected to comparators that operate motors for controlling the X and Y movement of a nozzle to guide it to the fire. Once this is done it will then trigger a timer and open a valve to distinguish the fire.
It is my understanding that these sensors can detect flame due to the wavelength they use, which is 200nm to 400nm. Other than that I don’t know enough about photodiodes to make any discrimination criteria.
I have already designed and tested most of the circuit, which includes the arming of the sensors, the motor control, turning the valve on, and the time for which the valve is on.
My intentions for the sensors is to use them in a way that gives me a varying voltage, which then would be put into a comparator. The output of the comparator would have three states A>B, A=B, and A<B. This information is then used to control the movement of the motors.
RE: Help needed in designing a circuit for photodiode.
Moreover, because of the smoke, the position determination can be rather dubious, as the smoke billows and changes, your calculated fire position will fluctuate wildly.
TTFN
RE: Help needed in designing a circuit for photodiode.
IRstuff I sure appreciate your insight and help on this.
RE: Help needed in designing a circuit for photodiode.
There also also the usual difficulties with false alarms and discrimination aganist expected things, such as people and smokers, as well as what do you do with the kitchen?
That's why standard fire control is done with straight-forward heat or smoke detection and broad area coverage with sprinklers. Consider that once your fire gets going and spreads, how would a single nozzle system deal with a spreading fire?
Standard smoke alarms are relatively simple conceptually, simply a light beam that's interrupted when smoke particles are present. BUT, they use a radioactive source to ionize the particles and there's some engineering to do to get the thresholds right.
TTFN
RE: Help needed in designing a circuit for photodiode.
RE: Help needed in designing a circuit for photodiode.
Here is a good start with some theory: http://www.siliconsensors.com/AN.html
RE: Help needed in designing a circuit for photodiode.
for the lenes i would use a polycarbonate one used for CD transport mechanisms. This can be purchased from Edmund Scientific along with the optical filter. For the PD, Talk to the guys at Fermionics in Simi Valley, CA. let me know if this helps!
RE: Help needed in designing a circuit for photodiode.
IRStuff is correct - these detectors are good at seeing fires which have low smoke evolution such as saturated hydrocarbons (the ones ending in ...ane), and alcohols for example.
A couple of manufacturers to have a look at are: Forney Fireye; Detronics. No doubt there are others.
RE: Help needed in designing a circuit for photodiode.