Hi,
I recently finished building a circuit from an earlier post (https://forum.allaboutcircuits.com/...itch-and-xor-gate-for-a-control-panel.178688/) that was intended to replace several SPST toggle switches to operate as momentary switches by using an XOR gate. The circuit is based on this original one posted by Crutschow:
https://forum.allaboutcircuits.com/attachments/138954/
In my new travel trailer there is a main switch control panel which has a mixture of momentary and spst switches for various lights and equipment. The spst switches all illuminate and the momentary ones obviously do not. Interestingly all 4 of the momentary switches control lights outside of the unit that I cannot see and have to go out at night to tell if they are on or off. I tried replacing the momentary switches with the spst, but discovered that the trailer has something like a latching relay setup so you would have to click the spst twice to get the lights to switch on, switch off (it is not an option to replace this latching setup as it is internal to the master control box of the unit)
I am using 3 of the XOR gates available in the CD4070B and tying the inputs on the 4th gate to ground as it is unused. When testing this setup. I noticed that when power is first applied, all of the outputs from the 3 XOR gates pulse HI, triggering the transistor and in turn energizing the relays. This has the effect that all the lights attached to the relays turn on which is not a desirable behavior. When storing the trailer for any length of time, the battery is disconnected so when I go to pick it up and reconnect the battery, all of the lights turn on.
The desired behavior is that the relay will only energize when a switch is activated and not when the circuit is initially energized.
I have tried researching articles related to suppressing pulses from logic gates on power-up but nothing looks like it will work. I am open to suggestions.
Thanks,
01134
I recently finished building a circuit from an earlier post (https://forum.allaboutcircuits.com/...itch-and-xor-gate-for-a-control-panel.178688/) that was intended to replace several SPST toggle switches to operate as momentary switches by using an XOR gate. The circuit is based on this original one posted by Crutschow:
https://forum.allaboutcircuits.com/attachments/138954/
In my new travel trailer there is a main switch control panel which has a mixture of momentary and spst switches for various lights and equipment. The spst switches all illuminate and the momentary ones obviously do not. Interestingly all 4 of the momentary switches control lights outside of the unit that I cannot see and have to go out at night to tell if they are on or off. I tried replacing the momentary switches with the spst, but discovered that the trailer has something like a latching relay setup so you would have to click the spst twice to get the lights to switch on, switch off (it is not an option to replace this latching setup as it is internal to the master control box of the unit)
I am using 3 of the XOR gates available in the CD4070B and tying the inputs on the 4th gate to ground as it is unused. When testing this setup. I noticed that when power is first applied, all of the outputs from the 3 XOR gates pulse HI, triggering the transistor and in turn energizing the relays. This has the effect that all the lights attached to the relays turn on which is not a desirable behavior. When storing the trailer for any length of time, the battery is disconnected so when I go to pick it up and reconnect the battery, all of the lights turn on.
The desired behavior is that the relay will only energize when a switch is activated and not when the circuit is initially energized.
I have tried researching articles related to suppressing pulses from logic gates on power-up but nothing looks like it will work. I am open to suggestions.
Thanks,
01134