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IR blaster needs more power

PostPosted: Tue Jun 04, 2019 3:46 am
by sblantipodi
Any suggestions on how to give a lot of power to my ir blaster?

I'm using this shield on my D1 Mini
https://wiki.wemos.cc/products:d1_mini_ ... ler_shield

If I connect only the ir blaster signal is powerful and it can easily achieve three or four meters without any problems.
If I connect other devices to my d1 mini board like a pir, a rele, a bme280, a 0.96" oled and two touch button the ir blaster is really weaker.

How can I solve the problem?

Should I add a capacitor or a resistor somewhere? Can you help me please?

Re: IR blaster needs more power

PostPosted: Tue Jun 04, 2019 5:41 am
by btidey
You don't say how you have wired it up or what pins you are connecting others sensors to. If they are separate then in principle there should be little effect.

The hat itself uses a mosfet transistor to connect the diodes through 51R resistors to the 3.3V supply. The drop of an ir diode will be about 1.5V so there will be about 35mA LED current which is fairly reasonable. Its a pity they didn't use the 5V supply for the LEDS as that would have been a better option keeping the LED current away from the 3.3V electronics.

It is possible the other sensors are loading the 3.3V supply too much but I don't think that is a likely cause as I'd expect random resets if there is an issue with its stability.

The other possibility is that if you are adding in code in the firmware for other sensors then you could be disturbing the timing of the IR signal generation which is quite critical. Some IR libraries do the timing in-line and if there are other interrupts then that could disturb things. The way to check that would be to just wire in the other sensors but not change the firmware from the version that gives you good results.

Re: IR blaster needs more power

PostPosted: Tue Jun 04, 2019 7:53 am
by sblantipodi
btidey wrote:You don't say how you have wired it up or what pins you are connecting others sensors to. If they are separate then in principle there should be little effect.

The hat itself uses a mosfet transistor to connect the diodes through 51R resistors to the 3.3V supply. The drop of an ir diode will be about 1.5V so there will be about 35mA LED current which is fairly reasonable. Its a pity they didn't use the 5V supply for the LEDS as that would have been a better option keeping the LED current away from the 3.3V electronics.

It is possible the other sensors are loading the 3.3V supply too much but I don't think that is a likely cause as I'd expect random resets if there is an issue with its stability.

The other possibility is that if you are adding in code in the firmware for other sensors then you could be disturbing the timing of the IR signal generation which is quite critical. Some IR libraries do the timing in-line and if there are other interrupts then that could disturb things. The way to check that would be to just wire in the other sensors but not change the firmware from the version that gives you good results.


thanks for the answer.
All sensors are connected to separate pin except BME280 sensor and OLED display that shares the D1 and D2 IC2 PINs.
I have a relè on D5, two touch button and a PIR on different pins (I don't remember exacly what pin)...

Everything is connected to 5V except BME280 that needs 3.3V and the IR shield that is connected on both 3.3V and 5V.

I don't think that is a problem of firmware since if I put the IR blaster nearer to the receiver, it always works.
So it's not a problem of "sometimes works and sometimes not" it's only a problem that the IR signal is weaker when all the sensors are connected.

Re: IR blaster needs more power

PostPosted: Tue Jun 04, 2019 1:45 pm
by sblantipodi
btidey wrote:You don't say how you have wired it up or what pins you are connecting others sensors to. If they are separate then in principle there should be little effect.

The hat itself uses a mosfet transistor to connect the diodes through 51R resistors to the 3.3V supply. The drop of an ir diode will be about 1.5V so there will be about 35mA LED current which is fairly reasonable. Its a pity they didn't use the 5V supply for the LEDS as that would have been a better option keeping the LED current away from the 3.3V electronics.

It is possible the other sensors are loading the 3.3V supply too much but I don't think that is a likely cause as I'd expect random resets if there is an issue with its stability.

The other possibility is that if you are adding in code in the firmware for other sensors then you could be disturbing the timing of the IR signal generation which is quite critical. Some IR libraries do the timing in-line and if there are other interrupts then that could disturb things. The way to check that would be to just wire in the other sensors but not change the firmware from the version that gives you good results.


you was right. it is my code.
if I install the same code without sensors except the ir blaster signal is weak.

how this can be possible? in my code I use the SparkFun BME280 library and the adafruit GFX library for the oled.
others are simple logic for MQTT, Wifi and touch buttons.

what can it be?