View Full Version : need hi speed photodiode

06-16-2010, 09:50 PM
I am trying to build a chronograph to Measure Projectile Velocity Optically
I need photodiode with response time less then 5 n sec & peek sensitivity 940 nm
Actual photodiode used in circuit is QSE773 with pair QEE123 (IR LED)
I am not able to get above mention parts can anybody help me

06-17-2010, 04:35 PM
mouser or farnell might have it. check out farnell.in.

06-18-2010, 12:12 PM
Thanks for info
I have placed an order for OP950 Photodiode

06-18-2010, 01:23 PM
where in india did u but it and at what price? dealer address and phone number please. It shoud be around 20Rs if u got 3-4 of them could u send me one of them!!!! I will pay for it


06-18-2010, 08:37 PM
I am from Mumbai & I order it from farnell Mumbai sales offices
Cost is Rs. 57/- each & I order 4 Nos.

For address http://in.farnell.com/jsp/content/freetoair.jsp?content=contact&_requestid=119176

For cost
http://in.farnell.com/jsp/search/browse.jsp;jsessionid=C0VM4WAO2XXJECWNBBSBFTY?N=50 0003+1002898&Ntk=gensearch_001|gensearch_001&Ntt=photodiode|op950&Ntx=mode+matchallpartial|mode+matchallpartial&displaytext=&_requestid=119262

06-19-2010, 04:46 PM
Thanks for sharing the info!!!!

06-20-2010, 11:32 PM
what will be the import duty (%) and other tax? I belive there will be beacuse farnell just have sales office, not a warehouse.

12-19-2010, 01:18 PM
Finally I got the compatible photodiode from farnell Bangalore office
For QSE 773 I got BPV22NF & for QEE123 I got SEP8706

I assemble the circuit as per the figure1 & the detail description of the figure1 circuit is given below

The screens consist of photodiodes and infrared LEDs.
The heart of the chronograph is the photodiode whose
reverse current is proportional to the amount of incident
light. Therefore, if you reverse bias the photodiode and
interrupt or diminish the amount of light as seen by the
photodiode, the reverse current will decrease. The momentary
decrease in reverse current develops a change in
voltage across R10 (Figure 1). This change in voltage is very
small (approximately 12 mV), so the op-amps U1A and
U1B (LM224) amplify it and feed it to the comparator U1C,
producing a TTL level trigger pulse which is sent to the μC
for timing purposes. This trigger pulse is also sent to a
monostable multivibrator U1D and illuminates the green
LED for about one second.

Now the problem is The Green LED (D1 LED2) continuously blinks when I connect the IR sensor
I assembled the circuit one more time on bread board also but same problem
Please help me to solve the problem