- Thu Mar 17, 2016 12:42 am
#43374
I know I'm looking for the current to power the opto LED.
- Thu Mar 17, 2016 8:45 am
#43398
optocoupler. Wanted to establish that driving relays of this type directly from 3v3 GPIO pins is not a problem as long as the relay coils are powered separately.
martinayotte wrote:Eh, guys !
Are you discussing about relay power consummation or the current needed for the LED to saturate the optocoupler ?
optocoupler. Wanted to establish that driving relays of this type directly from 3v3 GPIO pins is not a problem as long as the relay coils are powered separately.
- Thu Mar 17, 2016 9:48 am
#43402
Either I'm testing something wrong or the numbers don't add up.
I have:
Relay board: http://amzn.com/B00KTELP3I Note that his is NOT the SainSmart board but a "knock off perhaps". I have a 4 channel SainSmart board but it is in use.
power supply with 3.3v and 5v rails
5v to JD-VCC
Ground near JD-VCC to PS ground
3.3v to VCC near input pins
Ground near input pins to ground (don't think this is needed)
Then I touch negative lead of meter to power supply ground, positive to input 1 pin. Relay closes, meter reads 40ma.
In my limited understanding, this suggests 40 ma is traveling through that meter to the ground pin on the power supply (Actually the other direction isn't it...). If the meter were to be replaced with the huzzah, 40ma would travel through the esp to ground and thereby exceed rating 2:1.
Please, somebody have mercy on me and set me straight, this is driving me nuts.
I have:
Relay board: http://amzn.com/B00KTELP3I Note that his is NOT the SainSmart board but a "knock off perhaps". I have a 4 channel SainSmart board but it is in use.
power supply with 3.3v and 5v rails
5v to JD-VCC
Ground near JD-VCC to PS ground
3.3v to VCC near input pins
Ground near input pins to ground (don't think this is needed)
Then I touch negative lead of meter to power supply ground, positive to input 1 pin. Relay closes, meter reads 40ma.
In my limited understanding, this suggests 40 ma is traveling through that meter to the ground pin on the power supply (Actually the other direction isn't it...). If the meter were to be replaced with the huzzah, 40ma would travel through the esp to ground and thereby exceed rating 2:1.
Please, somebody have mercy on me and set me straight, this is driving me nuts.
- Thu Mar 17, 2016 11:00 am
#43407
I agree, your numbers don't add up. Can you configure your relay as follows:
The exact value of Ra and Rb are unimportant but they should be around 10 ohms, measure them before applying power. Verify that:
VCC to JD-VCC is an open circuit
Leave In1 disconnected, apply power and measure the following voltages:
3V3 to ground (should be 3V3)
5V to ground (should be 5V)
Voltage across Ra (should be close to 0)
Voltage across Rb (should be close to 0)
Connect In1 to ground. The indicator LED for relay 1 should turn on and the relay should close. Measure the following voltages:
Voltage across Ra (should be on the order of mv)
Voltage across Rb (should be on the order of hundreds of mv)
The exact value of Ra and Rb are unimportant but they should be around 10 ohms, measure them before applying power. Verify that:
VCC to JD-VCC is an open circuit
Leave In1 disconnected, apply power and measure the following voltages:
3V3 to ground (should be 3V3)
5V to ground (should be 5V)
Voltage across Ra (should be close to 0)
Voltage across Rb (should be close to 0)
Connect In1 to ground. The indicator LED for relay 1 should turn on and the relay should close. Measure the following voltages:
Voltage across Ra (should be on the order of mv)
Voltage across Rb (should be on the order of hundreds of mv)
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