After a many days of research I turned to stack overflow once again to help me.

I'm looking for High speed IR receiver circuit for laser-tag weapon. Requirements are High noise cancelation, high distance, high speed and low latency.

For obvious reason I can't use IrDA because of complicated protocols which are big overhead to latency. The only suitable solution for me is TSOP7000, but Vishay discontinued it's production.

Is there any way to build a receiver circuit, that replaces TSOP7000 or is there any replacement of this great receiver ?

Thank you very much.

EDIT: High level expectations: 16bits of data@<2ms.

For obvious reasons there is a problem with data collision. In ideal case, there will be one transmitter (gun) and one receiver (sensor) transferring data at once. But the main problem of laser tag guns is the collision. If multiple guns shoot at one sensor in the same time a data collision can occur. That's whole transfer should be executed in shortest time possible. IrDA cause massive overhead.

Most of the classical lasertag equipment is used in dark rooms completely restricted from son or lighting. That's the reason I need to think of the filters, to make game playable at classic hall.

Obviously, the data loss caused by technical background should be as small as possible. (I don't want some raging kid to smash my weapon on the ground)

  • 1
    \$\begingroup\$ First you define a spec that is realizable so we know you know what you are doing or at least how it is supposed to work... Bit rate, energy per bit, path loss, latency, packet length, SNR , BER . You can use IRDA 1 bit rates at 100kbps maybe up to 10m with an LED and further with a Laser, but you need to understand Friis Loss and BER vs SNR to design this. Sorry This is not an instructable site. BTW that chip is still avail but hard to find. and others exist. \$\endgroup\$ Commented Jul 15, 2017 at 0:41
  • \$\begingroup\$ If you want to copy an existing wireless protocol that is efficient , low latency and high energy/bit, then this chip with suitable Laser driver and Pin diode is a good choice to start after you have a protocol and spec in mind. digikey.com/product-detail/en/maxim-integrated/MAX3120CSA-T/… but dont reinvent the wheel find out what has been done already. In case you dont know bit rate or E/bit is inverse with range of energy for SNR considerations \$\endgroup\$ Commented Jul 15, 2017 at 2:14
  • \$\begingroup\$ did you define a bit & message rate and range yet? \$\endgroup\$ Commented Jul 15, 2017 at 5:09
  • \$\begingroup\$ @TonyStewart.EEsince'75 thank you for your comments. The terms you use are yet unknown to me. I'm mainly a software engineer and I'm just learning electronics. I added a closer specification to the question for you. About bit/message rate and range... Range is (I think) less relevant, as long as I use a lens directed light cone. The range with 8cm diameter cylinder should be > 70m. Carrier frequency vs data are not relevant, as long as i can deliver 2 byte message @ < 2ms \$\endgroup\$
    – Po1nt
    Commented Jul 15, 2017 at 7:18

2 Answers 2


For obvious reason I can't use IrDA because of complicated protocols which are big overhead to latency.

Of course you can use an IrDA receiver. All it does is handle the physical layer, this means convert light into electrical signals. It includes the circuitry you need, like filtering to get rid of slow ambient light variations, etc.

It doesn't know about the protocol at all, which will be implemented in some other chip like an IrDA controller or a micro.

You can use your choice of infrared emitter, and your own choice of signal... the chip will receive it. Example:


Now, you should:

  • Match laser optical wavelengths and sensor's maximum sensitivity
  • Put an optical filter in front of your sensor to filter out light at other wavelengths
  • Decide where to put the sensors on the target to get good coverage, maybe use some diffusers to ensure a hit anywhere on a large area is picked up by the sensor

Now, if you want it to work in daylight... that's gonna be more difficult. Most likely a modulated signal would work best over ambient light. In this case the simplest option could be an amplitude modulated signal at a rather high frequency (like 4-10 MHz). The receiver would be an AM receiver. This wouldn't be an IrDA chip though.

EDIT: Here's a suggestion.

  • Photodiode
  • Fast low noise amplifier
  • Tuned bandpass centered around your frequency (say, 10MHz)
  • Simple diode envelope detector

This would be rather crummy as a radio receiver, as it would detect all frequencies inside the bandpass' pass band equally, but you're unlikely to encounter other sources of pulsed infrared in the thick of the woods anyway. However it is rather simple, and does not need a PLL to track the incoming signal frequency (thus it has no lock time). The bandpass could be a highpass (but a tuned LC would provide better enhancement of your carrier). It would reject ambient light variations rather well, however care must be taken to avoid saturation in sunlight... maybe AC couple the input? I'm not really familiar with photodiode amplifiers.

  • \$\begingroup\$ Basically that's the problem. IrDA is not suitable for high noise environment. That's why they recommend so small distance. \$\endgroup\$
    – Po1nt
    Commented Jul 15, 2017 at 15:42
  • \$\begingroup\$ See edit for suggestion. \$\endgroup\$
    – bobflux
    Commented Jul 15, 2017 at 23:33

For reliable data reception, you need 15dB to 20dB SNR. With 10,000 bit per second datarate, your bandwidth will be approximately 10KHz. With thermal noise floor of 4.0 * 10^-21 watts/Hertz and 10,000Hz bw, the equivalent input noise power will be 4.0 e-21 * 1e+4 = 4.0 e-17 watts. For "clean" datalink, or 20dB stronger, you need 4.0e-15 watts.

The laser provides 0.01 watts, eyesafe, and will be de-focused to 1 foot diameter. Your detector is 1/8" square, or (12 * 8)^2 or ~~ 10,000th of the laser energy. The photodiode energy becomes 0.01 / 10,000 = 1 millionth of a watt.

You only need 4.0e-15 watt, but photodiode gets 1e-6watt, or 250 Million X stronger than needed.

You need a circuit, after the photodiode, that tolerates the sunlight.

This existing answer provides a starting circuit.

Optical communication module using LED and photodiode or sensors


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