Hi,
Question: How do I drive a 1A/24V relay which switches an AC resistive load ?
Attached: My block diagram with detailed pns of components Flow/Notes/Issues/:
1)I cannot change the 24V EM relay pn, it is fixed, everything else is flexible.
https://datasheet.lcsc.com/lcsc/1810051510_Hsin-Da-Precision-953-1C-24DG-2_C259300.pdf
Design Flow=
The '244 buffer boosts the RPi GPIO current and voltage aprox 3.0V.
The opto isolator module is used to isolate the AC load switching from the DC RPI control.
The 24V voltage doubler is required to generate the 24V required for the fixed relay
The N channel MOSFET (IRLB8721Pbf) is used as a switch, so when RPI GPIO goes high, the 24V/AA is switched onto the 24V relay
Status/Problems:
Circuit does not seem to be working.
2)Is the block diagram correct ?
3)If not, then how can I easily switch on 24V/1A to the relay ? What is a better design?
4)If the 24V relay is connected to the mosfet at the drain will the 24V from voltage doubler always be on or will it actually switch on/off depending on GPIO high/lo?
-The MOSFET datasheet has Fig 3 which shows at Vgs =2.5V, Ids = 1A of current. So I expected the mosfet to turn on at 2.5V.
Vgs is also specd at +/- 20V.
https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d462533600a40153566056732591
My expectation for mosfet to turn on at 2.5V may be an incorrect assumption.
thanks for your advice
Question: How do I drive a 1A/24V relay which switches an AC resistive load ?
Attached: My block diagram with detailed pns of components Flow/Notes/Issues/:
1)I cannot change the 24V EM relay pn, it is fixed, everything else is flexible.
https://datasheet.lcsc.com/lcsc/1810051510_Hsin-Da-Precision-953-1C-24DG-2_C259300.pdf
Design Flow=
The '244 buffer boosts the RPi GPIO current and voltage aprox 3.0V.
The opto isolator module is used to isolate the AC load switching from the DC RPI control.
The 24V voltage doubler is required to generate the 24V required for the fixed relay
The N channel MOSFET (IRLB8721Pbf) is used as a switch, so when RPI GPIO goes high, the 24V/AA is switched onto the 24V relay
Status/Problems:
Circuit does not seem to be working.
2)Is the block diagram correct ?
3)If not, then how can I easily switch on 24V/1A to the relay ? What is a better design?
4)If the 24V relay is connected to the mosfet at the drain will the 24V from voltage doubler always be on or will it actually switch on/off depending on GPIO high/lo?
-The MOSFET datasheet has Fig 3 which shows at Vgs =2.5V, Ids = 1A of current. So I expected the mosfet to turn on at 2.5V.
Vgs is also specd at +/- 20V.
https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d462533600a40153566056732591
My expectation for mosfet to turn on at 2.5V may be an incorrect assumption.
thanks for your advice