Dave's Transimpedance Amplifiers:  Page 1,     Page 2,     Page 3

• 10MHz TO 20MHz LASER LIGHT DETECTOR
  This circuit was originally designed to detect laser light pulses for an optical Ethernet communications system. It has good ambient light immunity.

• 1uS LIGHT PULSE RECEIVER PLUS POST AMP
  This circuit is designed to detect very weak light pulses lasting 1uS. It uses a tuned LC feedback network to provide high sensitivity while giving high ambient light immunity. A post voltage amplifier is included with a gain of about X20. The circuit is described in more detail in the receiver section of my Handbook of Optical Through the Air Communications.  Note: The LF357 op amp is no longer available, this circuit is for reference only.

• 40KHz LASER BURST DETECTOR
  This circuit was originally designed to detect weak flashed of laser light bounced off of a fabric video projection screen. It was used as part of a firearm training system. It generates a 100mS output pulse whenever it detects a 3ms to 5ms-laser burst, modulated at 40KHz. It is very sensitive and could be modified for long-range laser communications.

• 40KHz LIGHT RECEIVER IS IMMUNE TO AMBIENT LIGHT
  If you want even more sensitivity than the above circuit, try this design. When used with a one-centimeter square photodiode, you can achieve a range of several hundred feet with a standard TV or VCR remote control module.

• 40KHz MODULATED LIGHT DETECTOR
  This circuit uses a unique cascode amplifier circuit to convert the current from a PIN photo diode to a current without any feedback network. It is very stable and very sensitive. The circuit shown has the potential for a conversion factor of 10 volts per microwatt at 900nm. I included a simple JFET post-amplifier with a gain of about 20.