Infrared detector

[JShtaway]

Hi! I have design project in an engineering class I am currently enrolled in and hoped I could get a couple questions answered. The project I have is basically to design a circuit that can take a ir photodiode and turn on some Led's when the diode detects IR.

My question is that since the diode only lets 5u amps through when it detects IR light I need to find a way to provide more current to the LED's. I was thinking of using an op-amp and having the op-amp supply the current and the necessary voltage, but how much current can an op-amp supply? and if it cannot supply enough can you give me any ideas on what else I can try?

Note. I only have +12volt supply and a ground (car battery)

Of course Im not looking for anyone to do my project, Im just looking for ideas.

Thanks alot!
Jennifer

 

[crutschow]

An op amp is a good choice to amplify the current (use a transimpedance amplifier configuration) but, for a typical op amp, you will need to add a transistor driver on the output to supply the current for the LEDs. Since you only have a single supply, you will also want an op amp designed for single supply use such as these National Semiconductor devices. Most other op amp manufacturers also make single-supply or rail-to-rail type op amps.

 

[Space Varmint]

An op amp is a good choice to amplify the current (use a transimpedance amplifier configuration) but, for a typical op amp, you will need to add a transistor driver on the output to supply the current for the LEDs. Since you only have a single supply, you will also want an op amp designed for single supply use such as these National Semiconductor devices. Most other op amp manufacturers also make single-supply or rail-to-rail type op amps.

I saw a trick today on YouTube. He used a small solar cell as an IR detector which could give more drive. Also you might try a buffer amp on the output of the IR detector. An emitter follower or even better a Darlington pair.