I want to make a simple ladder circuit to control the on and off of a light bulb using 2 switches, but I am going to manipulate one of the switches by means of a microcontroller, and also I don't want to use a relay because they wear out with time. I am trying with this circuit with optocouplers, a pnp transistor and triacs, as seen in the image, but it does not work well, also when I am simulating it in proteus 8.9 after a certain time it throws me these errors:

[SPICE] DELMIN increased to 8.88178e-016 due to lack of time precision [SPICE] transient GMIN stepping at time = 6.54158 [SPICE] TRAN: Timestep too small; timestep = 1.11022e-016: trouble with node # $ IAC AMMETER # 0020_AVS1 # AB # branch.

enter image description here

I don't know what I'm doing wrong, I already tried it on a breadboard and it doesn't work either.

If someone can help me or suggest another circuit that works for what I need, I appreciate it a lot and forgive my English.

  • \$\begingroup\$ You are trying to drive your triacs from a 5 volt supply (V2) and this won't work because the triac circuit is not sharing the same ground as your 5 volts. You need a proper triac driver circuit and not guesswork. \$\endgroup\$ – Andy aka Dec 7 '20 at 14:45
  • \$\begingroup\$ Under the AC 120V 60Hz power supply next to the light bulb, I put the ground 5V (V2), I am sharing it with the neutral of the AC signal, that is, if they share the same ground. Or am I doing it wrong? \$\endgroup\$ – andresuarez_95 Dec 7 '20 at 14:55
  • \$\begingroup\$ The GND of your digital circuit should not be common to AC neutral. That's incredibly dangerous. \$\endgroup\$ – BB ON Dec 7 '20 at 15:12
  • \$\begingroup\$ Sorry, I'm not an electronics expert, but I understand that if GND can be shared, for that reason I did so. So how can I do it? \$\endgroup\$ – andresuarez_95 Dec 7 '20 at 15:18

Use a solid state relay (SSR)

Some examples include...
AQH3223 , 600V, 1.2A, DIP-8

CPC1976Y , 600V 2A, AC Zero Cross, SIP-4


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