Triple-555 timer circuit not working in Proteus

Question

I am new to 555 Timers and Proteus and I need help to fix a circuit I have built. The intended function of the circuit is as follows.

• The logic is controlled by an external circuit but it is represented by logic toggles within this circuit to purely test the 555 Timer functionality. -The logic toggles will be user controlled in this circuit and they control which 555 timer must be turned on using logic 1.
• Only one 555 timer must function at any time as each 555 timer output has been configured with the use of resistors and capacitors to roughly drive the motor (depicted as a lamp) at respective speeds. - The speeds configured by U1, U2 and U5 should roughly be 80V, 150V and 220V. For example, if U1 is toggled on by logic 1, the motor must be driven at 80V.
• I calculated the resistances and capacitance to produced the desired speeds and rounded them up to the nearest whole number for ease of building. I am however unsure if I calculated them correctly.

I have tried simulating in Proteus but I got the following errors which I cannot solve.

I would appreciate if anyone can kindly assist in determining the problem and perhaps provide a solution.

Answer 1

Logic toggle is supposed to be a logic input and therefore cannot be used as a power source.

For any 555 models inside Proteus, if you connect GND properly but leave the VCC pin unconnected (i.e. unpowered), Proteus will assume that the 555 is powered from the POWER terminal, which is a 5V source located under TERMINALS. So, actually, all 555 subcircuits in your simulation are running regardless of the toggle states (You can verify this by simulating one of your 555 circuits with VCC unconnected, in a separate simulation file).

If you want to simulate user activation of individual 555 oscillators then you should use the SPDT switch. Press P to open the Pick Devices window and search for SW-SPDT. There are momentary and latched versions, so pick one suits your needs and connect like following (POWER can be a POWER terminal from TERMINALS window, or a DC voltage source):

^{simulate this circuit – Schematic created using CircuitLab}

One another problem with your circuit is that there is no current limiting resistor for the optocoupler's LED. Place a few hundreds of ohms or even a few kiloohms. And adjust according to your needs. Plus, adding a pulldown resistor to SCR's gate (between gate and low-side anode) and a series resistor to optotriac's output would help. A few hundreds of ohms should work.

Final note: Proteus sometimes needs ground on the isolated side as well.