how big a relay? those pins can only course ~50ma
This simply tells the Compiler to make a variable ac of type byte (8 bits) and this variable cannot be changed, i.e. it is a constant equal to the value A4.
As mentioned, never measure component resistance when components are powered.
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Thanks for the warning on measuring resistance during operation. I was just using the beep function on the multimeter, it's not enough connection to ground to get the meter to sound its beep. I'm getting 5v across the low output pin, 0.5v across the high output pin.
- Are your meter leads: black (neg) connected to 0V (GND) and red (pos) connected to the output pin, with the meter set to DC volts ?
Give us a link to the relay module’s data sheet.
I was measuring pos 5v to the pin to get those readings, when I measure the pins to ground as you suggest I'm only getting 4.9v. Maybe a pullup resistor on the output pins?
I can't find the datasheet, but it's this module- 12V 10Amp Forward and Reverse Relay Module for Motor / Linear Actuator, Reversing Relay Module
- Data sheet:
https://www.czh-labs.com/tmp/madeimg/datasheet/f-1020.pdf?_gl=1*1yvuq1t*_up*MQ.._gaODk5NDI1MTI4LjE3MTA1Mzc0MTk._ga_SWTWKN09K5MTcxMDUzNzQxOC4xLjAuMTcxMDUzNzQxOC4wLjAuMA..
- This is troubling:
- Think you had better use an interposing relay (or MOSFET) and control it with the Arduino.
"in your case, the demands of your project, the 5V 40mA output is inadequate."
Thanks everyone. Great community!
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