| ??? 10/01/10 19:55 Modified: 10/01/10 19:57 Read: times |
#178847 - Optos don't actually "isolate" from a EMC point-of-view... Responding to: ???'s previous message |
Anita said:
No, the relay coil get the supply from the same instrument itself but what i am making is a industrial type conroller.
The MCU circuit has 3V, and the relay output [and 4-20mA analogue output] circuit has 12V power supply. Anita, this isn't actually needed, if you follow good old standard design practise. Just the opposite: You think everything is isolated (which is not, remember stray capacitances!) which makes you feel that you can omit proper decoupling and star grounding measures! And, BANG, you are falling into the trap... I have seen many "fully isolated" designs, which were way more vulnerable to EMI than non-isolated, conventional designs, relying on proper decoupling and star grounding techniques!! Kai Klaas |
| Topic | Author | Date |
| PC817 for isolation + driving relay? | 01/01/70 00:00 | |
| Why isolate relay coil? | 01/01/70 00:00 | |
| Re: | 01/01/70 00:00 | |
| Optos don't actually "isolate" from a EMC point-of-view... | 01/01/70 00:00 | |
| ......... | 01/01/70 00:00 | |
Star point grounding and filtering... | 01/01/70 00:00 | |
| PC817? | 01/01/70 00:00 | |
| Is LED current of 5mA is sufficient? | 01/01/70 00:00 | |
| no | 01/01/70 00:00 | |
| A darlington? | 01/01/70 00:00 | |
| SSR? | 01/01/70 00:00 | |
| RE: "book by Bosshcart " | 01/01/70 00:00 | |
| RE: "book by Bosshcart " - Link | 01/01/70 00:00 |