| ??? 02/15/06 15:40 Read: times |
#110069 - Exactly! Responding to: ???'s previous message |
Mahmood said:
Could it be because they coat the contacts with special material to stop corroding the contacts during sparking. and this could affect low current for it increases the contact resistance? Exactly! Take a relay with Cadmiumoxid for instance. This material is so bad, that contacts are not glittering at all. It looks like oxidized conatcts, what it is actually!! But to switch heavy or even inductive loads, there's nothing better. Corroding of contacts by sparking is minimal. Such contact material is totally unsuited to switch light loads, or even dry loads, where no power is switched at all. Dry loads are best be switched by gold contacts and certain alloys resting in inert gas ambient. Silver and silver alloy contacts can be used for light loads but not for dry loads. Unfortunately, these expensive relay contacts are heavily eroded by even the least sparking. When I was younger I repaired stage amps. The most often damage was the relays used to switch-on and -off loudspeaker at output of amp. After some time, they are not able to let pass music without producing noise and having set outs. It turned out, that contact material was unsuited. Exchanging them by relays having good silver alloy contacts could fix the damage. Kai |
| Topic | Author | Date |
| monitoring mains voltage | 01/01/70 00:00 | |
| Opto with capacitor | 01/01/70 00:00 | |
| re opto with cap | 01/01/70 00:00 | |
| Some protective components required | 01/01/70 00:00 | |
| Fire risk | 01/01/70 00:00 | |
| Transformer | 01/01/70 00:00 | |
| thats the best chioce | 01/01/70 00:00 | |
| There's nothing wrong | 01/01/70 00:00 | |
| Space | 01/01/70 00:00 | |
| please do not go aargh | 01/01/70 00:00 | |
| Opto isolator = LDR + Neon? | 01/01/70 00:00 | |
| 10mA? | 01/01/70 00:00 | |
| Hmmm | 01/01/70 00:00 | |
| Why not... | 01/01/70 00:00 | |
| Neon + Photodiode | 01/01/70 00:00 | |
| Loosing brightness | 01/01/70 00:00 | |
| Transformer isolation is needed! | 01/01/70 00:00 | |
| Previously, on 8052.com | 01/01/70 00:00 | |
| Safety first | 01/01/70 00:00 | |
| Transformer | 01/01/70 00:00 | |
| Sorry | 01/01/70 00:00 | |
| two places to look | 01/01/70 00:00 | |
| Annoying, isn't it?! | 01/01/70 00:00 | |
| Thanx! | 01/01/70 00:00 | |
| maybe Amveco 6200 series? | 01/01/70 00:00 | |
| Transformers | 01/01/70 00:00 | |
| Could also be used | 01/01/70 00:00 | |
| an Idea | 01/01/70 00:00 | |
| The simplest ideas are the best | 01/01/70 00:00 | |
| Poor dads | 01/01/70 00:00 | |
| Tainted food | 01/01/70 00:00 | |
| Yes, but... | 01/01/70 00:00 | |
| Low current | 01/01/70 00:00 | |
Exactly! | 01/01/70 00:00 |