X
Advertisement

1,046 questions

1,221 answers

206 comments

785 users

how to prevent voltage/power drop to arduino when AC compressor kicks in

169 views
0 votes
how to prevent voltage/power drop to arduino when AC compressor kicks in

My Electrical question:

 

Background:

 

House furnace fan power supplies 120 VAC to my attic 120 VAC AC in line duct fans.  

 

I have a micro controller (Arduino) which controls two dampers in the attic to redirect the air flow to either the two bedrooms OR the hall and bathroom.

 

https://www.arduino.cc/en/main/arduinoBoardUno

 

The arduino, damper power, and optically isolated relay power come from this circuit.

 

I have put a receptical on the 120 VAC line to provide power to the system.

 

The Arduino is powered by a 9V DC 650 mA plug in power supply plugged into the receptical.

The optically isolated relays are powered by 5V DC plug in power supply plugged into the receptical.

The electric dampers are powered by a 24 VAC plug in power supply plugged into the receptical.

 

Works great.  The arduino cycles the two dampers every 30 minutes as long as there is 120 VAC coming from the furnace fan.

 

 

Problem:

 

When the AC compressor kicks in there appears to be a voltage drop resulting in the arduino rebooting.  Equivalent to powering down the arduino and then powering it backup.  I have observed this first hand when the AC compressor kicks in.  The reboot is instantaneous.

 

 

Solution:

 

Can I put a capacitor across the 9V DC leads into the arduino to mitigate the momentary voltage drop?  What kind and type of capacitor (assuming I know what I am doing) do I need.

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Helvetica; -webkit-text-stroke: #000000} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Helvetica; -webkit-text-stroke: #000000; min-height: 17.0px} p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Helvetica; color: #042eee; -webkit-text-stroke: #042eee} span.s1 {font-kerning: none} span.s2 {text-decoration: underline ; font-kerning: none}

HELP!!!!!!!!

asked May 2, 2017 by john_armsby (120 points)

1 Answer

0 votes

An interesting and frustrating problem but relatively common.  I would first get your AC power checked; you should not have that type of power drop when the Compressor cuts in.  I am assuming your compressor is 220V.  You should also see your lights flicker and or dim with what you describe, if not you have a circuit problem that needs immediate attention.  This also indicates that the drop out is quite long allowing your 9V power supply to collapse, again assuming it is a regulated supply.

I am not sure what you are saying with a instant reboot, as I do not know what your code looks like.  If it is kicking it out it should be like a normal power on reset.  It is common when large motors start there is an inductive transient generated on the power line, it is possible that is what you are seeing.  I base this on the problems goes away when you add capacitance.

To size the capacitor I would start with 1000uF per amp on the 9 volt side.  When you have enough to fix the problem double the value, paralleling two is the best approach.  Reason someday one will fail; the other will keep it working.  The capacitor would be a cheap aluminum cap, lead orientation doesn’t matter get one that fits your design.  e sure the 9V power supply is ok and not on its death bed.

I think the most important thing is to check the wiring; it must be #12 minimum to the furnace.  I think what is really causing the problem is the furnace blower, it is on the same circuit as your controls and comes on with the compressor.
answered Jun 11, 2017 by gilshultzhome-com (17,730 points)

Related questions

  • 0 votes
answered Jan 3, 2013 by (920 points)
  • 0 votes
  • 1 answer
  • 247 views
  • 0 votes
  • 1 answer
  • 98 views
asked Jul 21, 2013 by email (3,720 points)
  • 0 votes
  • 2 answers
  • 1.3K views

1,046 questions

1,221 answers

206 comments

785 users

Latest Article Comments

Measuring Air...
"@sasitharan73: The mentioned components is a 10K PTC Thermister (1002). Note, this revision (P)"
Measuring Air...
"I purchased the Wind Sensor Rev. P model. In that model i want some details about the component and"
Build Your Own Digital FM Radio Transmitter with...
"Thank you, T.K. Will report back"
Build Your Own Digital FM Radio Transmitter with...
"@porrick: Not tried NS73M FM module yet! Usually you need to connect just 6 pins of NS73M for"
Build Your Own Digital FM Radio Transmitter with...
"Do I even need to solder leads to all 8+7 (15)"
Build Your Own Digital FM Radio Transmitter with...
"Hi - I bought an FM transmitter from SparkFun (product URL at bottom). In fact, I bought ~8 of"
S-Video to RCA Cable...
"correction (test it): White (blue wire) is L audio, Red is R audio. image for"
Continuity Tester Differentiates...
"One more change I did, I replaced the green led with a 3v"
Continuity Tester Differentiates...
"Tried a 3.7v small lipo and still works. This is perfect for checking pcb"
electroschematics group on facebook
...
  Search 4 million + Products
Browse Products