I’m using Aduino Mega 2560 supported with a 9V, 1A power supply. The board is directly driving an LCD 1602 display. When the Beefcake Relay is energized the voltage drops from ~5V to ~4.5V with a current draw for the relay of 0.14A. This causes the LCD display to dim and often jumble the displayed characters. So, I’m look for options to resolve this issue. Thanks for you time.
Can you please provide a picture of your setup?
You might be overheating your Mega’s voltage regulator. If you use a 6 volt power supply, do things work better?
Please see the attached picture of the set-up. Besides driving the 1602 LCD display there’s also an HX711 load cell amp (tied to a load cell), and an RTC (DS3231). The Beefcake Relay can cause the LCD issues without a load but it is more pronounced when driving a 110V solenoid.
Thanks for your time.
I’ll investigate the 6V suggestion when I get a chance. Thanks for the idea.
Also, the relay draws a fair amount of current. Try connecting the relay’s power directly to the Arduino and run a second wire from the 5V pin on the relay to your breadboard. If you can, use a thicker wire between the Arduino and relay board. Popping a 100 to 1000uF capacitor on your breadboard power rails might help too.
Well connecting the power directly to the board and the second wire from 5V pin on the relay to the breadboard didn’t help. The 1000uF capacitor across the power rails virtually eliminated the voltage droop, LCD diming and reduced the frequency of the display getting jumbled but it did not eliminate it completely. It does seem to occur now when the relay is de-energized which makes me think that perhaps there’s some noise issue on the control line which I can’t see without an Oscope. Any other suggestions? (I suspect that if I hadn’t decided to drive the LCD directly from the Arduino there might not be an issue due to the additional isolation that would be in play.) Thanks for your time, insight, suggestions.
Maybe try a separate 5 volt power supply on the relay, but if you do that make sure the ground from that supply connects to the Arduino’s ground as well.
I did as you suggested with a separate 5V PS for the relay but the problem remains. Any thoughts on putting an opto-isolator on the control line?
Thanks.
You could give that a try, I don’t know if it will solve your issue though. Unfortunately I don’t know exactly what might be causing the problem so I can’t give much direction in solving it other than just trying different things until you find something that works.
I appreciate your support. I think I’ll give the opto-isolator a shot. I’ll report back the results… it’ll be a while before I get one to try.
So the final resolution was to add the 1000uF capacitor across the 5V and GND rails which resolved the voltage droop (display dimming issue) and add 0.1uF capacitors on each of the data lines as well as the Enable and Register Select lines on the LCD. This appears to have resolved the issue. Note that I believe that having the relay drive a 110V solenoid was at the heart of what I believe is a noise issue of some sort. Thanks for the support.
TS-Chris:
Try connecting the relay’s power directly to the Arduino and run a second wire from the 5V pin on the relay to your breadboard.
Help me understand this. I will be embarking on my first BeefCake project shortly. I am new to Arduinos (3 wks). For ‘power’ I only know of the single 5v and 3.3v supply pins on the Arduino Uno, right above the A0-A5 pins.
What is this ‘2nd power terminal’ I am inferring in the above quote? In parallel or otherwise, is there not only one source of power (5v or 3.3v) to drive LEDs, Relays, etc???
That means, run 5 volts directly from the 5 volt pin on the Arduino to the 5 volt pin on the relay, then run a second parallel wire from the 5 volt pin on the relay to the lower current parts that need power.