110VAC to a readable output for micro controller

Thread Starter

RoninGSX

Joined Jun 10, 2020
4
I am trying to figure out the best way to tackle my project and need some guidance. I am using a SSR to control an electrical device with my controller. This works fine. However, I am wanting to integrate a safety measure and be able to "sense" when the power goes out based on the SSR input. I have looked at adding an additional SSR using the same receptacle AC plug for the input and ~5VDC load, an AC voltage sensor, etc. Basically I just need some sort of signal to tell me when I have lost power to the SSR. Any thoughts or products I should be looking at?

I have tried to find SSR's that have a load range of ~3-30 VDC and input of 110VAC but these are hard to find.

-Ronin
 

dendad

Joined Feb 20, 2016
3,564
Do you mean a loss of mains power?
If so, how about an indicator lamp on the power, and a LDR on an Arduino analog input?
Or an opto isolator?
Or having the Arduino powered from a transformer the shares its power input with the SSR?

Or do you want to sense the SSR output? That could make use of a current transformer.
A bit more info on what you want may help.
 

Thread Starter

RoninGSX

Joined Jun 10, 2020
4
Yes I mean a loss of mains power to the SSR.

The device is directly plugged into main through the SSR but the controller gets its power through USB power from the computer that is plugged into a UPS (I need the board to keep power during an outage to go through a shutdown process for another device.

I was thinking of maybe just using a switching power supply (<-like this one) to send a 5V signal to my MC and when the pin loses the signal it can initiate my shutdown sequence.
 

DickCappels

Joined Aug 21, 2008
6,457
1591900075814.png
(Circuit found on the web)

The output of this should be approximately 50% duty cycle at line frequency. If you put a capacitor between the optocoupler's collector and emitter you will get a signal that is high when no AC is present and low when AC is present.
 

BobaMosfet

Joined Jul 1, 2009
1,118
I am trying to figure out the best way to tackle my project and need some guidance. I am using a SSR to control an electrical device with my controller. This works fine. However, I am wanting to integrate a safety measure and be able to "sense" when the power goes out based on the SSR input. I have looked at adding an additional SSR using the same receptacle AC plug for the input and ~5VDC load, an AC voltage sensor, etc. Basically I just need some sort of signal to tell me when I have lost power to the SSR. Any thoughts or products I should be looking at?

I have tried to find SSR's that have a load range of ~3-30 VDC and input of 110VAC but these are hard to find.

-Ronin
This is one of the primary uses of a ZC (Zero Cross) Detector circuit. Not only can you use it for powering your MCU, you can use it to determine when power stops. Use something like a 4N35 Opto to isolate your circuit. Look elsewhere in this forum for Zero Cross Detector, and you can find one of the best (full schematic and link to original Author's page).
 

Reloadron

Joined Jan 15, 2015
5,505
I have tried to find SSR's that have a load range of ~3-30 VDC and input of 110VAC but these are hard to find.
Hard to find? Just off the top Crydom and many others come to mind. Here are some examples. You make no mention of load current? Besides those posted a simple Google of mains voltage opto couplers should get you a dozen hits including circuits like that posted by Dick in post #4 of this thread.

Ron
 

Thread Starter

RoninGSX

Joined Jun 10, 2020
4
Hard to find? Just off the top Crydom and many others come to mind.
When I did my search, I had missed a few search criteria and the results were very few. I had redone the search and did in fact find many and even ordered a Crydom SSR last week. Thank you for the input!
 

MaxHeadRoom

Joined Jul 18, 2013
20,888
If this is just used for detection, OPto22 have a large selection of opto isolated input and output modules that can be used directly with a micro etc. interface to AC DC I/O etc.
In fact I have a very large inventory of old stock of these of all stripes.
Also many on ebay.

1592239109808.png

Max.
 

BobaMosfet

Joined Jul 1, 2009
1,118
MCR100 & MCR106 are the most commonly used for these kinds of things, in TO-92 package. Reasonably priced, wonderful thyristors (SCR), and very useful.
 
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