Relay output

[wdariusw]

Hello. I have six 230V input signals (from room thermostats) . I need to have relay output if all of them are active. So, i do not have idea how to do that without 7 relays. How it is possible to do using other electronic components and one relay ? Any ideas ? Thanks !

 

[Tha fios agaibh]

You could use a 7414 "And" gate ic, but you'd need to convert your 230vac signals to logic level.

 

[wdariusw]

You could use a 7414 "And" gate ic, but you'd need to convert your 230vac signals to logic level.

If i will have logic level signal, then there are a million solutions for doing what I need. But if i only have 230V and do not want to convert it to another voltage ?

 

[Harald Kapp]

What output power do you need to switch? A small solution for low power can be made with optocouplers:

The 'output' here is conducting when all input voltages are present. If one or more input voltage is missing, the associated optocoupler will be off and the output will be high-resistance (wired and function).
You'll have to design the capacitors and resistors such that the optocouplers do not turn off when during the zero crossing of the input voltage.
You may want to split the series resistors in 2 and place the capacitor in between to reduce the voltage level across the capacitor:

Ideally place a zener diode parallel to the capacitor to protect it from overvoltage.

 

[Tha fios agaibh]

Perhaps a smart relay or a plc controler?

 

[wdariusw]

Output will be small power, only signal for turning boiler ON. So there is bridge rectifier feeds optocoupler, and the optocoupler outputs are in series... I think this is quiet simple and proper way. But need to choose proper components.

 

[BobK]

That circuit will put a lot of power through the resistors. If 10mA is needed for the optocoupler, that would be 2.3W each.

Bob

 

[Harald Kapp]

If 10mA is needed for the optocoupler, that would be 2.3W each.

Completely right, but you can get optocouplers that work from as little as ~1mA. Not the type I used in my illustration, though.

In terms of power dissipation using a scaled down voltage (resistive divider) plus some logic will be far more efficient, but that's not what the op wants.

 

[KMoffett]

This should work:

http://uk.farnell.com/fairchild-semiconductor/mid400/optocoupler-logic-o-p-dip-b/dp/1467846
http://www.farnell.com/datasheets/2183353.pdf?_ga=1.153099760.97767030.1484942284

Ken

 

[Harald Kapp]

Nice find, Ken.