Generic - Pulse counter Issue

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TD-er
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Re: Generic - Pulse counter Issue

#11 Post by TD-er » 27 May 2018, 14:10

mr-varga wrote: 27 May 2018, 11:08 I feed the unit with 8,5V in Vin input. And at the end of the reed I have 3.22V.
Do you have any sensor connected to this (relative high) voltage?
And what signal level is sent to the ESP device input pins?

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Re: Generic - Pulse counter Issue

#12 Post by mr-varga » 28 May 2018, 16:24

Yes this output is also a power supply for LDR and his output go in analog input in ESP.
All the 3.3V and Groung in my board is used.

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Re: Generic - Pulse counter Issue

#13 Post by mr-varga » 06 Jun 2018, 21:28

Could be a problem of the 3.3V supply? I have many devices connected to the internal regulator. SHT10 sensor, bmp180 sensor, ldr for light measurement.
This is all. You suggest to use external 3.3V power supply?

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Re: Generic - Pulse counter Issue

#14 Post by TD-er » 06 Jun 2018, 23:16

You have to make sure the signals from the sensors to the ESP do not exceed 3v3.
The analog input often is from 0...1V, but on some boards there are already resistors present to allow for a higher range.

I don't know if the voltage regulator on your board can handle such a high voltage.

If you take those issues into account, I see no reason why you shouldn't use 8.5 V as power supply.

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Re: Generic - Pulse counter Issue

#15 Post by mr-varga » 09 Jun 2018, 12:29

The board is a ESP8266 NODEMCU. This one:
Image
And I have 12V power supply in place so for power the board I use a step down dc dc:
Image
(in this the output is set to 8,5V) to power the NodeMcu in the GND and Vin pins.
For the reed switch of the counter i pick a 3.3V and Gnd from two pins of NodeMcu board.

Is all this correct?

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Re: Generic - Pulse counter Issue

#16 Post by TD-er » 09 Jun 2018, 13:43

The AMS1117 on the NodeMCU board is a so called "linear regulator", which means they're not switching.
Let's say you're running at 5V and the output of that regulator is 3V3.
Then you're having 1.7V over the regulator. (5 - 3.3)
At 100 mA, that's 170 mWatt of energy lost.
When feeding from 8.3V, then there is 5V over the regulator.
At 100 mA, that's 500 mWatt lost. (and quite some heat)

When you place a switching regulator in front of it, you're making it a bit more efficient, since that switching regulator has an efficiency of about 80 - 85%.


I don't understand what you mean with your last question.
For the reed switch of the counter i pick a 3.3V and Gnd from two pins of NodeMcu board.
A reed switch short circuits the contacts. So you also need some resistor in series with the reed switch.
And then connect the point where the reed switch and the resistor meet, to a GPIO pin of the ESP.

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Re: Generic - Pulse counter Issue

#17 Post by mr-varga » 10 Jun 2018, 01:07

Ok thanks I understand now, so I have to regulate the step down near to 3.3V to optimize the consumption and heat.

The reed switch is connect like the picture in the first post, but I don't know why he always count... It seems to be a interference...

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Re: Generic - Pulse counter Issue

#18 Post by TD-er » 10 Jun 2018, 10:35

mr-varga wrote: 10 Jun 2018, 01:07 Ok thanks I understand now, so I have to regulate the step down near to 3.3V to optimize the consumption and heat.

The reed switch is connect like the picture in the first post, but I don't know why he always count... It seems to be a interference...
If the AMS1117 is still in the loop, you have to make sure you feed it with a high enough voltage.
Most regulators need some minimum voltage drop.
So just feed it with 5V, just to be sure.
And a lot of sensors need 5V too, so that's useful too.

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