My first arduino Mega shield does not work ;)

Other Hardware General Electronics
21

DO NOT do that it will burn out the MOSFET!!!

22

Hi, @rogerlette

Do you have a DMM? Digital MultiMeter?

Tom.. :smiley: :+1: :coffee: :australia:

23

Jim,

Thanks you very much, I will update the pin number of the mofset and the zener diode voltage. Anyway, I'll make sure to use the components you mentionned.

So, for me we can close the topic :wink: Thanks again for your very precious help. I'll keep you informed when I receive the new board. (within 3 weeks)

Thanks Tom for your question ; No I have a simple standard multimeter.. Why ?

24

It is invaluable for trouble shooting. Just Volts and Ohms.

Tom.. :smiley: :+1: :coffee: :australia:

25

Hello everyone,

I received the new board but I have some strange behaviours..

When I set an output to high, the indicating LED is switch on, but the outup is 0V.
When I set an output to low, the indicating LED is switch off, but the outup is 20V.

This is not a big problem for me but.. there is another one.

  • When I supply an electrovalve with 24V from a desk power supply. I can hear it changing it's position.
  • When I supply this same electrovalve throught the output of the board, and the board is powered by the same power supply :
  • I cant hear the electrovalve switching.
  • And the indicating LED is switched on (despite the indicating LED is normally off when the output deliver 20V, like explain above)

I also tried to replace the electrovalve with a 24V LED :slight_smile:

  • I can see the 24V LED switched on when the output is LOW
  • I can see the 24V LED switched off when the output is HIGH
  • The indicator LED on the board stays ON.

I'm sorry but I dont understand what is happening ?

Once again, thanks by advance for your help,
Roman M.

26

Where are you connecting the valve?
It should be between Vcc and EL1 on your diagram.

Yes, the Mega output HIGH, turns EL817 ON, this turns Q1 ON, this connects Q1 Drain to Source, so EL1 is at gnd, the LED via its 4k7 resistor has 24V across it so the LED turns ON.

Yes, the Mega output LOW, turns EL817 OFF, this turns Q1 OFF, Q1 Drain is no longer connected to Source, so EL1 is pulled to Vcc by the LED and 4k7 resistor.
The LED current is very LOW so the LED turns OFF.

Can you please post some images of your project?
So we can see your component layout.

Tom... :smiley: :+1: :coffee: :australia:

27

Did you connect the valve between EL and GND?

28

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