Attached picture shows my circuit. In it I use only one IR sensor (TSOP1738) but now I want to add another IR sensor (TSOP1738) to my circuit. So my questions are: 1. Is it possible? 2. How (parallel or series)? Thanks.enter image description here

  • \$\begingroup\$ The capacitor shown may stop the unit from working. It should be between VCC and Gnd. The absolute maximum sink current for the output pin is 5mA. \$\endgroup\$ Commented Sep 7, 2018 at 4:45
  • \$\begingroup\$ Can you confirm all you need the circuit to do is flash an LED when it sees an infrared signal? If so, for the 2nd sensor, do you want to add a 2nd LED or do you want the same LED to flash with input from both Sensors? \$\endgroup\$
    – RJR
    Commented Sep 7, 2018 at 5:50
  • \$\begingroup\$ Yes I only need LED flash. and I want the same LED flashs with input from both sensors. \$\endgroup\$
    – Hosein
    Commented Sep 7, 2018 at 6:53

1 Answer 1


Yes, both are common emitter output and can share 1 pullup R.

But your supply voltage AC noise ought be < 1mV for best range. ok?

That means the LED may need a separate V+ path to source and ground path must not drop mV to avoid long range Rx noise during detection.

Add a low ESR bulk e-cap to Vcc,Gnd, 100uF?

But 100uF load wont work well on output as the cap will draw large currents. Ic=CdV/dt
You need a transistor on outputs to boost current or better CMOS 1 shot to buffer IR Rx then stretch pulse with diode, 1uF, 1Meg decay then output 330 to 1K from CMOS Inverter to LED.

  • \$\begingroup\$ Thanks. So can you propose new circuit based your answer. \$\endgroup\$
    – Hosein
    Commented Sep 7, 2018 at 5:55
  • \$\begingroup\$ common emitter => open collector: a common emitter output can still be part of a totem-pole. \$\endgroup\$ Commented Sep 7, 2018 at 8:24
  • \$\begingroup\$ Hosein, I did propose a new circuit that does not draw high current with a time delay, read again until you understand \$\endgroup\$ Commented Sep 7, 2018 at 12:52

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