I am using the moc3023 for phase control of a triac. see attachment for a circuit Fairchild semiconductor has sent me. the Fairchild circuit actually shows a 360ohm between the 240vac line and the moc3023. I used a 1000 in a ltspice simulation which showed 90w power over the resistor.
when I built the circuit with a 360 ohm 1/4 watt resistor this blew the resistor immediately. this is not hard to see as you are dropping 240v over the resistor. when I contacted Fairchild they said to use at least a 1watt resistor.I now have some rox3s 3w metal oxide film resistors. will these withstand the 240v?
The rox3s are rated at 350v which doesn't seem to mean much when they are only 3w. the length of pulse shown on the spice simulation is a max of 80us.
can anybody suggest the power of the resistor I should use? and is their a calculation to show the power dissipation over a very short period of time?
thanks.
sorry I couldn't do the attachment as is was the wrong file type for this application.
when I built the circuit with a 360 ohm 1/4 watt resistor this blew the resistor immediately. this is not hard to see as you are dropping 240v over the resistor. when I contacted Fairchild they said to use at least a 1watt resistor.I now have some rox3s 3w metal oxide film resistors. will these withstand the 240v?
The rox3s are rated at 350v which doesn't seem to mean much when they are only 3w. the length of pulse shown on the spice simulation is a max of 80us.
can anybody suggest the power of the resistor I should use? and is their a calculation to show the power dissipation over a very short period of time?
thanks.
sorry I couldn't do the attachment as is was the wrong file type for this application.