bought a remote control light sw device, but want it to act as a 2-way sw using existing normal wall light sw and with no relays on when the light is off. The relevant bit of the remote device:
12v through relay (ie this supply switches the relay, the other side of the relay is mains AC) grounds via s8050 npn transistor (this does the remote switching). Specifically:
collector to relay
base to switching device
emittor to -ve

using presumably more transistor(s) i want to make this work as a 2-way sw using the existing wall sw as the other sw. I have had a good crack after googling about transistor 2-way switches, but no result. I can't get my head round how to do it, maybe because it is the ground being switched not the +ve?
+5v is also available on the board.
help appreciated.
James

 

You have to state your country of origin, the terminology is different from N.A. to UK. etc. Two way switch is different in N.A.
http://www.lightwiring.co.uk/lighti...switching-and-switches-uk-and-us-terminology/
Max.

 

I'm in UK, meaning 2-way switch as in domestic light switch where either of 2 switches may be used to control a light eg. one at top of stairs, one at bottom.

 

In N.A. that is a 3 way!

Do you want to sub the switch for a relay?
Or retain the switch also?
If so you may have to set it up as a Intermediate type.
Max.

 

I'm in UK, meaning 2-way switch as in domestic light switch where either of 2 switches may be used to control a light eg. one at top of stairs, one at bottom.

Here is a diagram of the UK two-way circuit, all you need to do is take a 3core cable from the existing switch to the new one.

 

I'm in UK, meaning 2-way switch as in domestic light switch where either of 2 switches may be used to control a light eg. one at top of stairs, one at bottom.

Something you need to look at is the availability of neutral in the switch boxes. While for a two way switch neutral through the actual boxes housing the switches was not required when using today's newer remote switching systems a neutral line is required. This became apparent in the US when the 2011 issue of the NEC (National Electric Code) book required a neutral line to be run through all switch boxes. I can't speak for the UK andit is something to consider. The below image shows a pair of switch boxes using a neutral feed through the boxes with a wire nut tie in each box.



You may want to see what you have in the switch boxes.

Ron

 

That pic shows UK, but UK does not allow wire nuts, still AFAIK.
.We used to do it (long ago) the easy way with a live and switch wire to one switch and 3 conductor between switches.
Max.

 

Here's an alternative drawing turned in by one of my students, it's wrong but it works....

 

Here's an alternative drawing turned in by one of my students, it's wrong but it works....

Same as post #7 That was the way we did it back when I apprenticed in the UK.
Just that we took a live and switch wire down to same switch.
Max.

 

I'm familiar with how a domestic 2-way switch is wired. the remote control switch naturally culminates in a relay being switched. it is a simple one position on/off type rather than the also common 2-postion/ 2-way type of relay. i could change the relay for the other type and wire as above but the relay would at times be powered with the light being off. i want to create the effect using more transistors and using the existing wall switch. (and the supplied relay). in this scenario the wall switch would have 5v passing through it..

 

Post a drawing of what you are trying to do.
Max.

 

Still not quite sure what you want to achieve but if you want to remotely control the 2 way and also keep both switches, why not convert to intermediate switching using the relay?
Max.