NVR= Non Volatile Ram. That may be an EEPEOM, or some other kind.

The atmega328 has 1kbyte of non-volatile EEPROM for remembering stuff across resets. So using the internal oscillator you measure the time for, say, a nominal 10sec and work out a correction factor, then store that for future use with a calibration program.

The CAP1206 will work too.

Thanks.

I was thinking about different ways the same functionality I have right now can be achieved(cut-off lamps asa the door is opened with maximum reliability). I am listing all of them below, I would like to hear your thoughts on which one you find the most reliable.

1) The AC mains supply to load is connected through the microswitch then to a optocoupler and the two relays. The optocoupler output is read by the uC and the relays are turned on only if the mains are closed. Irrespective of whatever causes the failure, the supply is cut-off as soon as the door is opened. I think this is the most safest option. But also feel adding more components can in-turn increase the probable points of failure.

2) The circuit how its done now. Two relays, one for controlling power and the other for turning the load on or off.

3) Same as 1 but only one relay instead of two. This again guarantees that the supply is cut-off as soon as the door is opened.

 

One more option is to have the power cord unplug from the system with an IEC (computer style) connection, with the plug eld by the door, so that opening the door will unplug the power. That is a fail-proof arrangement and costs less as well. I think that I suggested it much earlier, also. It seems that most folks like the much more complex arrangements.

 

One more option is to have the power cord unplug from the system with an IEC (computer style) connection, with the plug eld by the door, so that opening the door will unplug the power. That is a fail-proof arrangement and costs less as well. I think that I suggested it much earlier, also. It seems that most folks like the much more complex arrangements.

Nicee.. I will think about the mechanical placements, etc.

Do i need to be concerned about arc on the switch contacts when they opened and closed repeatedly? The switches are rated for 3x my max current consumption.

And this the optocoupler circuit I am planning to implementing. Let me know your suggestions.

Thanks

 

Nicee.. I will think about the mechanical placements, etc.

Do i need to be concerned about arc on the switch contacts when they opened and closed repeatedly? The switches are rated for 3x my max current consumption.

And this the optocoupler circuit I am planning to implementing. Let me know your suggestions.

Thanks

Since under normal operation the system would be off when the enclosure is opened there would never be any arcing. The interlocking is only intended for safety and so it is not opened with the power on except as an error.

 

Since under normal operation the system would be off when the enclosure is opened there would never be any arcing. The interlocking is only intended for safety and so it is not opened with the power on except as an error.

Ok cool. Did you take a look at the optocoupler circuit? Can I reliably use that to sense the mains switch state?

 

Ok cool. Did you take a look at the optocoupler circuit? Can I reliably use that to sense the mains switch state?

I did look at that optocoupler circuit and it should work. One thing is that the voltage rating on the two resistors R1 and R2, does matter in this application. Also, that portion of the circuit will have mains potential present and so it will be important to maintain adequate separation from the rest of the circuit board traces. There is a lot of information about those rules available. And you can inspect circuit boards from other mains operated systems for examples of the separations desired.

 

I did look at that optocoupler circuit and it should work. One thing is that the voltage rating on the two resistors R1 and R2, does matter in this application. Also, that portion of the circuit will have mains potential present and so it will be important to maintain adequate separation from the rest of the circuit board traces. There is a lot of information about those rules available. And you can inspect circuit boards from other mains operated systems for examples of the separations desired.

Ok, Thanks a lot

 

I wasn't able to work much the previous week. Now I am back at it.

I have made some progress. I have selected a MCU - ATmega1608 and replaced the touch controller from CAP1206 to MTCH105 as the latter gives digital output which can be easily read.

I'm still confused about power supply choice. I have 3 options.
IRM-10-5
RECOM RAC10-K/277
TDK LAMBDA ZWS-10-30B

Do I need to need to add any caps or something to reduce noise ?

Thanks