See scanned notes below.
I've got a wireless relay module that I'm trying to hack in order to interface a couple of sensors with it. The top right of the scanned doc shows the original configuration, standard NPN low side switch. What I want to do is add a condition that my sensor (with another NPN transistor as output) must also be ON in order for the relay to switch. I can't figure whether I should put my sensor output transistor in series with the gate of the original transistor (middle right of scan), or whether I should put it series with the relay coil (bottom right of scan).
Please advise. I would just try one or the other, but I want to get it right the first time, as I don't have a lot of component leg to work with and if I screw it up, I might have to wait until tuesday to get replacement parts.
Thanks.
I've got a wireless relay module that I'm trying to hack in order to interface a couple of sensors with it. The top right of the scanned doc shows the original configuration, standard NPN low side switch. What I want to do is add a condition that my sensor (with another NPN transistor as output) must also be ON in order for the relay to switch. I can't figure whether I should put my sensor output transistor in series with the gate of the original transistor (middle right of scan), or whether I should put it series with the relay coil (bottom right of scan).
Please advise. I would just try one or the other, but I want to get it right the first time, as I don't have a lot of component leg to work with and if I screw it up, I might have to wait until tuesday to get replacement parts.
Thanks.
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