| ??? 01/26/06 07:47 Read: times |
#108329 - More.... Responding to: ???'s previous message |
Triacs will turn off when the current across them falls below a certain value (see the bta41 datasheet). Depending on the load, the current zerocrossing may not be the same as the voltage zerocrossing. If the load is resistive, the current zerocrossing is in phase with the voltage zerocrossing. If the load is complex, then the current zerocrossing could occur just about anywhere.
If the lamp load is some form of discharge lamp, then these are more difficult to dim, incandescent lamps are quite easy. As for motors, synchronous motors generally don't like having a phase controlled waveform fed into them and don't like to be speed controlled in this way. However, some fan motors are designed for this and can cope with the temperature rise. Be sure to follow the snubbing guidelines for the opto and the triac. A 100nF X2 cap and two 330R 1W resistors is a good start. |
| Topic | Author | Date |
| MOC3021 | 01/01/70 00:00 | |
| Triacs only turn off at zero | 01/01/70 00:00 | |
| Motor, bulb | 01/01/70 00:00 | |
| More.... | 01/01/70 00:00 | |
| dI/dt | 01/01/70 00:00 | |
... or was it dV/dt ? | 01/01/70 00:00 | |
| Triac | 01/01/70 00:00 | |
| Domestic light dimmers use triacs | 01/01/70 00:00 | |
| Clarification required! | 01/01/70 00:00 | |
| Triac current and voltage | 01/01/70 00:00 | |
| the link linked to is dead | 01/01/70 00:00 | |
| Triac magic | 01/01/70 00:00 | |
| T shirt | 01/01/70 00:00 | |
| Well. | 01/01/70 00:00 | |
| Inductive loads | 01/01/70 00:00 |